The reactivity series
5 This question is about displacement reactions. 7 Mary wants to find the position of tin in the
The list below shows part of the reactivity series. reactivity series. She has the materials listed below.
Use it to help you answer the question.
Solutions Metals
zinc iron chloride solution iron
iron lead nitrate solution lead
lead tin chloride solution tin
copper zinc chloride solution zinc
a Predict which of the pairs of substances [2] a Mary adds a small piece of zinc to each solution
below will react. in turn. She writes her observations in the
table below.
i Copper and zinc oxide.
ii Lead and copper oxide. Solution Observations on
adding zinc metal
iii Zinc and lead oxide. iron chloride
lead nitrate silvery metal formed
iv Lead and iron oxide. tin chloride
grey metal formed
b Write word equations for the pairs of [2]
substances in part (a) that react. grey metal formed
6 Caz puts a piece of zinc in some copper sulfate i What conclusion can Mary make from [1]
solution. the observations in the table?
A reaction takes place.
The word equation for the reaction is: ii Suggest why Mary did not add a piece [1]
zinc + copper sulfate of zinc to zinc chloride solution.
copper + zinc sulfate
b Mary adds a small piece of tin to each solution
a Name the products of the reaction. [1] in turn. She writes her observations in the
table below.
b Explain why the reaction is a [1] Solution Observations on
displacement reaction. adding tin metal
iron chloride
c Caz places a piece of zinc in some nickel lead nitrate no reaction
nitrate solution. zinc chloride
A displacement reaction takes place. grey metal formed
no reaction
i Which metal is more reactive, nickel or [2] Write a conclusion that Mary can make [1]
zinc? Explain how you know. from the observations in this table.
ii Write a word equation for the reaction. [2] c Suggest one more investigation that Mary
could do to confirm the position of tin in the
iii Predict what would happen if Caz placed reactivity series. [2]
a piece of nickel in zinc chloride solution.
Give a reason for your prediction. [2]
199
11.1 Making salts – acids and
metals
Objective
■ Describe how to make salts What are salts?
by reacting acids with metals These pictures show some crystals. What do they have in common?
Copper sulfate crystals. Manganese chloride crystals. Nickel nitrate crystals.
The crystals are all samples of salts. A salt is a compound made when a metal
replaces the hydrogen in an acid.
Different acids make different salts:
●● hydrochloric acid makes chlorides
●● sulfuric acid makes sulfates
●● nitric acid makes nitrates.
50 30 Making magnesium chloride
40 cm3
30 Choosing reactants
cm3 20
20 Seeta wants to make magnesium chloride. She needs two reactants. One is
10 hydrochloric acid. The other reactant must include magnesium. Seeta could
use magnesium metal, magnesium oxide, or magnesium carbonate. She
decides to use magnesium metal.
There is a pattern in the reactions of metals with acids. When a metal reacts
with an acid, there are two products – a salt and hydrogen.
So when magnesium reacts with hydrochloric acid, the products are
magnesium chloride and hydrogen. The word equation for the reaction is:
magnesium + hydrochloric acid magnesium chloride + hydrogen
There is 25 cm3 of hydrochloric The chemical reaction
acid in the measuring cylinder.
Seeta measures out 25 cm3 of dilute hydrochloric acid. She uses a measuring
cylinder. A measuring cylinder measures smaller differences in volume than a
beaker. Seeta pours the acid into a beaker.
200
Seeta adds a small piece of magnesium ribbon to the acid in the beaker. The Making salts
magnesium reacts with the acid. Bubbles of hydrogen gas form. After a few
seconds, the bubbles stop. All the magnesium has reacted with the acid. stirring rod
dilute
Seeta adds another piece of magnesium to the acid. She continues to add hydrochloric acid
magnesium until there are no more bubbles. A piece of magnesium remains.
It has not reacted, because all the acid has been used up. beaker
Separating magnesium chloride from the mixture bubbles of
Seeta’s beaker contains a mixture. The mixture includes: hydrogen gas
magnesium
●● magnesium chloride solution Magnesium reacts with
hydrochloric acid. Bubbles of
●● solid magnesium. hydrogen gas form.
Seeta wants to make pure magnesium chloride. First, she filters the mixture.
This removes the solid magnesium.
Next, Seeta pours the magnesium chloride solution into an evaporating dish. She
heats the solution. Water evaporates. When about half the water has evaporated,
Seeta stops heating. She places the evaporating dish in a warm place.
filter paper
filter funnel magnesium
magnesium chloride solution
chloride
solution
magnesium
magnesium evaporating dish
chloride solution
Evaporation removes water from
Filtration removes unreacted the solution.
magnesium from the mixture.
A few days later, Seeta looks into the evaporating dish. She sees beautiful
white crystals. She has made her salt, magnesium chloride.
1 Jay makes a salt from a metal and an acid. Name the process used to separate the salt Make salts from acids and
solution from unreacted metal. metals by:
● reacting an acid with excess
2 Write a word equation for the reaction of zinc with hydrochloric acid. Name the salt
made in this reaction. metal
● filtering to remove unreacted
3 Name the metal and acid that you could react to make magnesium nitrate crystals.
metal
● heating to remove water.
201
11.2 Making salts – acids and
carbonates
Objective
■ Describe how to make Killing fungi
salts by reacting acids with Fungi can seriously damage crops. They reduce crop yield and crop quality.
carbonates Fungicides destroy fungi. Some farmers use fungicides from natural
sources, such as the neem tree. Some farmers use fungicides that are made
in factories, such as copper sulfate.
Different fungi attack different plants The fungus on these grapes can be
causing damage to their leaves, seeds or controlled using copper sulfate.
fruit, and roots.
Making copper sulfate
Choosing reactants
Copper sulfate is a salt. It is made in the reactions below.
stirring rod copper ●● Reaction 1
carbonate sulfuric acid + copper copper sulfate + hydrogen
powder The acid must be concentrated and the temperature high.
●● Reaction 2 copper sulfate + water
sulfuric acid + copper oxide
Dilute acid may be used.
●● Reaction 3 copper sulfate + water + carbon
sulfuric acid + copper carbonate
dilute dioxide
sulfuric acid Dilute acid may be used.
Copper carbonate and sulfuric On a large scale, copper sulfate is made in reactions 1 and 2. At school, you can
acid react together to make use reactions 2 or 3 to make copper sulfate solution. Reaction 1 is too hazardous.
copper sulfate solution, water, and
bubbles of carbon dioxide gas. The chemical reaction
202 Sisira plans to make copper sulfate solution from sulfuric acid and copper
carbonate.
Making salts
He measures out 25 cm3 of acid. He pours it into a beaker. He adds one copper sulfate
spatula measure of copper carbonate powder. Carbon dioxide gas forms, solution
and the reacting mixture bubbles. Sisira continues to add copper carbonate.
Eventually, no more bubbles form. The reaction has finished. evaporating
basin
Separating copper sulfate from the mixture
The beaker now contains a mixture of: Bunsen
●● copper sulfate solution burner
●● solid copper carbonate that has not reacted.
Sisira filters the mixture to remove solid copper carbonate from the mixture. On heating, water evaporates
He collects the copper sulfate solution in an evaporating dish. from the copper sulfate solution.
Sisira heats the copper sulfate solution over a flame. Some of its water
evaporates. Some of the mixture spits out. copper sulfate
Sisira removes the evaporating dish from the heat, and places it in a warm solution
room for a few days. The remaining water evaporates. Blue copper sulfate
crystals are formed. evaporating
basin
Evaluating and improving methods
Sisira makes a smaller mass of copper sulfate crystals than expected. He lost boiling
some of the product when heating the copper sulfate solution. water
Sisira decides to improve his method. He repeats the whole experiment. This
time, he does not heat the copper sulfate solution over a flame. Instead, he Bunsen
uses a water bath. This heats the solution more evenly. The solution does not burner
spit. Sisira ends up with a greater mass of crystals.
Heating over a water bath.
A pattern of reactions
When a metal reacts with a carbonate, three products are formed:
●● a salt
●● carbon dioxide
●● water.
The equations show some examples:
hydrochloric acid + copper carbonate copper chloride + carbon dioxide + water
nitric acid + magnesium carbonate magnesium nitrate + carbon dioxide + water
sulfuric acid + zinc carbonate zinc sulfate + carbon dioxide + water
1 Maddie makes a salt from a metal carbonate and an acid. Name the process used to Make salts from acids and
separate the salt solution from water. carbonates by:
● reacting an acid with excess
2 Write a word equation for the reaction of zinc carbonate with hydrochloric acid, and
name the salt made in this reaction. metal carbonate
● filtering to remove unreacted
3 Name the metal carbonate and acid that you could react to make zinc nitrate crystals.
metal carbonate
● heating to remove water.
203
Extension
11.3 Making salts – acids and
alkalis
Objective Sodium chloride
■ Describe how to make salts
Sodium chloride preserves and flavours food. It helps to dye clothes. It is used
by reacting acids with alkalis to make other important chemicals, such as chlorine and sodium hydroxide.
On a large scale, sodium chloride is extracted from the sea, or mined as rock salt.
In 2010, India produced more But you can make sodium chloride in the laboratory – read on to find out how.
than 15 million tonnes of sodium
chloride. Egypt produced Making salt
2.4 million tonnes.
Choosing reactants
How to make sodium chloride from its elements is described on page 114. But
burning sodium in chlorine is hazardous and the sodium chloride produced is
not pure.
sodium + chlorine sodium chloride
You can also make sodium chloride by neutralising an acid with an alkali.
hydrochloric acid + sodium carbonate sodium chloride + water
How much sodium carbonate?
When dilute hydrochloric acid reacts to neutralise sodium carbonate, there
is nothing to see. Both reactants are soluble in water. How do you know how
much acid to add?
Azalee follows the stages shown in the pictures below to make sodium
chloride crystals.
12 3 Add charcoal
powder. This
Dilute hydrochloric Add sodium removes the
acid and Universal carbonate solution colour.
Indicator. to make a neutral
The solution is red. solution. The
solution is green.
45
lter paper heat over a sodium
water bath chloride
black charcoal solution
powder
water
sodium chloride
solution
Azalee’s method for making sodium chloride crystals.
204
Making salts
Bem uses a different method to make sodium chloride solution. He uses a burette
burette and pipette, and indicator solution, to measure the volume of acid
needed to exactly neutralise 25.00 cm3 of sodium carbonate solution. He pours
away this mixture, and repeats the method without indicator. Then he heats
the sodium chloride solution over a water bath.
Evaluating the two methods hydrochloric
acid solution
Both Azalee and Bem started with the same amounts of reactants. Bem made
more sodium chloride than Azalee. The students evaluated their methods to conical ask
work out why.
white tile
Azalee filtered her mixture to remove the charcoal powder. Some of the
sodium chloride solution soaked into the filter paper. Azalee lost some of sodium carbonate
her product. solution
Bem did not need to filter his mixture. He did not lose any product in the first Some of Bem's apparatus for
stages of his method. making sodium chloride crystals.
Bem and Azalee heated their sodium chloride solutions over a water bath.
Some of the water evaporated. They both lost very little sodium chloride at
this stage. This stage does not explain why they made different amounts of
sodium chloride. The difference is explained only by Azalee’s filtering.
Azalee and Bem discussed their results further.
I did my reaction twice. I had to throw
away my first mixture of sodium chloride solution
and indicator. So I wasted lots of chemicals.
Azalee removed the indicator from her solution,
so she wasted less. Maybe Azalee’s method was
better, after all!
I only had to do my
reaction once. I lost some
sodium chloride when filtering.
That’s all.
1 Julia makes a salt by reacting an acid and an alkali. She uses an indicator to find out Make salts from acids and
the volumes of solutions that react together. Describe how to separate the indicator alkalis by:
from the salt solution. ● reacting an acid with an
2 Write a word equation for the reaction of potassium hydroxide with nitric acid, and alkali – use an indicator
name the salt made. ● heating to remove water.
3 Name the acid and alkali that you could react to make potassium chloride crystals. 205
Extension Making salts – fertilisers
11.4 Why add fertiliser?
Objective Plants use water, and carbon dioxide from the air, to make glucose. Glucose
■ Identify salts used as fertilisers is a compound made up of the elements carbon, hydrogen, and oxygen. Its
formula is C6H12O6.
The bag shows the elements in Plants need other elements, too. They need nitrogen to make proteins. They
a fertiliser. need phosphorus to form flowers and seeds. They need potassium to protect
burette them against disease.
dilute
sulfuric acid Plants get nitrogen, phosphorus, and potassium minerals from the soil. Farmers
increase crop yields by adding fertiliser to the soil. Some fertilisers, such as
conical flask manure and compost, occur naturally. Other fertilisers are made in factories.
dilute ammonia
solution Making fertilisers
Madu’s apparatus.
Most nitrogen fertilisers are made from ammonia. Ammonia is a compound
206 of nitrogen and hydrogen. Its formula is NH3.
Ammonia dissolves in water to make an alkaline solution. In the laboratory,
you can react ammonia solution with acids. These neutralisation reactions
make salts. The salts are used as fertilisers.
Which salts?
The equations show the reactions of ammonia solution with acids.
ammonia + sulfuric acid ammonium sulfate + water
ammonia + hydrochloric acid ammonium chloride + water
ammonia + nitric acid ammonium nitrate + water
Ammonium nitrate contains more nitrogen than the other ammonium salts.
Farmers add ammonium sulfate to alkaline soil. The salt provides nitrogen for
plant growth, and makes the soil less acidic.
Making ammonium sulfate
Madu plans to make ammonium sulfate. He pours 25 cm3 of ammonia
solution into a conical flask. He pours sulfuric acid into a burette.
Madu adds 1 cm3 of acid to the ammonia solution in the flask. The acid reacts
with some of the ammonia solution. Madu removes a drop of the mixture.
He drops it onto blue litmus paper. The paper remains blue. The flask contains
some ammonia solution that has not reacted.
Madu repeats the step reaction
above several times. He mixture
adds more and more acid.
Eventually, the litmus goes blue litmus
red. Madu has now added paper
enough acid to neutralise
all the ammonia. The flask teat
now contains a mixture pipette
of ammonium sulfate and
water. There is a tiny bit of Madu removes a drop of mixture from the flask. He
extra acid, too. drops it onto blue litmus paper.
Making salts
Separating ammonium sulfate from the mixture
Madu uses evaporation to remove water from the ammonium sulfate solution.
evaporating dish
ammonium sulfate
solution
boiling
water
Bunsen
burner
Evaporation removes water from
ammonium sulfate solution.
When about half the water has evaporated, Madu stops heating. He leaves the
ammonium sulfate solution in a warm place. The rest of the water evaporates.
Ammonium sulfate crystals remain.
Fertiliser production
We use huge amounts of fertiliser. One common fertiliser that is made from
ammonia is urea. In 2009, factories made about 190 000 million tonnes of urea.
The pie chart shows the five countries that produced the most urea.
Rest of world China
41% 33%
India
13%
Russia
USA 4% Indonesia
4% 5%
The top five urea-producing countries in 2009.
1 Name the fertiliser made by reacting ammonia solution with dilute nitric acid. ● Ammonium nitrate and
2 Name the process that removes water from a solution of a fertiliser. ammonium sulfate are useful
fertilisers.
207
Review i Name the products of the reaction of [1]
copper carbonate with sulfuric acid.
11.5
ii Write a word equation for the reaction
of copper carbonate with sulfuric acid. [1]
1 From the list below, choose the one best definition iii Name the products of the reaction of [1]
of a salt. copper oxide with sulfuric acid.
A compound made when an element replaces iv Write a word equation for the reaction [1]
the hydrogen in an acid. of copper oxide with sulfuric acid.
A compound made when a metal replaces c Zafira decides to use copper oxide. She places
the hydrogen in an acid. 25 cm3 of sulfuric acid in a beaker. She adds
black copper oxide powder until the copper
A substance that preserves and flavours food. oxide stops reacting.
Chloride and sulfate compounds. [1]
2 Name the salts made when the following pairs of spatula
substances react.
copper oxide
a Magnesium and sulfuric acid. [1] powder
b Zinc and hydrochloric acid. [1] beaker
c Magnesium and nitric acid. [1]
d Copper carbonate and hydrochloric acid. [1] sulfuric acid
e Zinc oxide and sulfuric acid. [1] i Name the three substances in the
beaker when Zafira has finished adding
f Copper oxide and nitric acid. [1] copper oxide powder.
3 Hydrogen gas is produced when a metal reacts [3]
with an acid.
[1] ii Describe how Zafira can separate the [1]
a Describe how to test for hydrogen gas. [1] copper oxide powder from the other
substances in the mixture.
b Describe what you would observe in your
test if hydrogen is present. d Zafira now has a solution of copper sulfate.
Describe how she can use the apparatus
4 Copy and complete the word equations below. below to obtain copper sulfate crystals from
a magnesium + nitric acid [1] the solution.
b zinc + sulfuric acid [1]
c magnesium + hydrochloric acid [1] tripod and
d copper carbonate + hydrochloric acid [1] gauze
e zinc oxide + nitric acid [1]
5 Zafira wants to make some copper sulfate crystals.
a Name the acid she needs. [1]
b Zafira has a choice. She could add either beaker evaporating Bunsen
copper carbonate or copper oxide to the dish burner
acid to make her crystals.
[3]
208
Making salts
6 Rizki uses the apparatus below to make copper 7 Lia plans to make zinc chloride crystals. She
chloride crystals. decides to react zinc metal with hydrochloric acid.
cm3 50 a The products of the reaction are zinc chloride
45
40 solution and hydrogen gas. Write a word
35
30 equation for the reaction. [2]
25
20 b Lia uses a secondary source to list the hazards
15 of the reactants and products.
10
5 Substance Hazard
zinc metal Low hazard
measuring beaker evaporating bunsen dilute hydrochloric acid Low hazard. May cause
cylinder dish burner harm in eyes or in a cut.
hydrogen gas Extremely flammable.
Forms explosive mixture
zinc chloride solution with air.
(dilute) Low hazard.
zinc chloride crystals and
concentrated solutions of Corrosive. Burns skin.
zinc chloride Harmful if swallowed.
tripod and spatula filter
gauze funnel
a Rizki makes copper chloride from copper Lia takes the precautions below to reduce risks
carbonate and hydrochloric acid. from the hazards. Give one reason for each
precaution.
i Name the gas made in the reaction. [1] i Be careful not to spill the acid. [1]
ii Write a word equation for the reaction. [2] ii When adding zinc metal to the acid,
make sure there are no flames nearby.
b Rizki follows the steps below for making his [1]
crystals, but they are not in the correct order.
iii Wear eye protection at all stages of the
A Measure out 25 cm3 of hydrochloric acid. experiment. [1]
B Pour the solution into an evaporating dish. iv Do not touch the zinc chloride crystals. [1]
C Heat the solution until about half its water has c Lia makes zinc chloride solution. She pours the
evaporated. solution into an evaporating dish. She does not
heat the solution directly. Instead, she heats the
D Add copper carbonate, spatula by spatula, until solution over a water bath. Suggest why.
there is no more bubbling.
zinc chloride
E Place the evaporating dish on a water bath. solution
F Filter the mixture. Keep the solution. boiling
water
G Place the evaporating dish and its contents in a
warm room.
H Wait for a few days to allow the rest of the water
to evaporate.
Write the correct order for the steps above.
The first one is A. [5]
[1]
209
12.1 Rates of reaction
Objective Fast or slow?
■ Understand how to follow
Fireworks explode in the sky. A car rusts. Some chemical reactions, such
the rate of a reaction that as those in fireworks, happen very quickly. Others, such as rusting, are
produces a gas much slower.
Chemical reactions in fireworks are Rusting reactions are very slow.
very fast.
Chemists need to control reaction rates. They may try to slow down rusting
reactions. They may try to speed up reactions that make useful chemicals,
such as soap, fertilisers, or medicines.
Following a reaction
Before chemists can control reaction rates, they need to find out how fast a
reaction is. You cannot tell how quickly a reaction happens just by looking
at its equation. You need to do an experiment to find out – how quickly is a
reactant used up? How quickly does a product form?
Vijay wants to find out about the rate of the reaction of magnesium with
hydrochloric acid. The equation for the reaction is below.
magnesium + hydrochloric acid magnesium chloride + hydrogen
Obtaining and presenting evidence
Vijay sets up the apparatus on the right. hydrogen
He drops a piece of magnesium into the
acid. He observes bubbles. The bubbles gas
contain hydrogen gas. As the hydrogen syringe
gas forms, it goes into the gas syringe.
The plunger moves out.
Vijay measures the total volume of gas that hydrochloric
has been produced by the reaction at the acid
end of each minute. magnesium
He draws a table for his results:
● The variable he changes (time) is in the left column.
● The variable he measures (volume of gas) is in the big right column.
Vijay wants to reduce error and make sure his results are reliable, so he
decides to repeat his investigation. His table has space for three results for
each test, and for an average value.
210
Rates of reaction
Time Total volume of gas formed by the end of this minute (cm3)
(minutes) 1 2 3 average
0000
0 31 30 32 31
1 45 47 49 47
2 64 68 66 66
3 69 69 66 68
4 76 76 79 77
5 83 85 81 83
6 83 83 83 83
7 84 82 83 83
8
Vijay chooses how to present his results. The variable he changes, volume of gas produced since start (cm3) 90
and the variable he measures, are continuous. This means he can 80
plot a line graph: 70
60
● The scale for the variable he changes is on the x-axis. 50
40
● The scale for the variable he measures is on the y-axis. 30
20
Vijay makes sure the numbers on each axis are evenly spaced. 10
0
Vijay draws a cross for each point. He then draws a line of best
fit. This is a smooth curve. The number of points above and 02468
below the line are similar. time (minutes)
Describing patterns and interpreting results
At first, the graph rises steeply. This shows that hydrogen is
formed quickly at the start of the reaction. The rate of the
reaction is fast. Then the slope of the graph gets less steep.
This shows that the reaction is slowing down. The rate of the
reaction is slower.
From the sixth minute onwards, the graph does not go up any
more. No more hydrogen gas is being made. This shows that the
reaction has finished. All the magnesium has been used up, so
there is nothing left for the acid to react with.
1 Give an example of a very fast reaction, and a very slow reaction. ● In a reaction that makes a
gas, the total amount of gas
2 Use the graph above to estimate the volume of gas made during the first 2.5 minutes made by the end of each
of the reaction. minute shows how the rate of
reaction changes over time.
3 Explain how the graph shows when the reaction has finished.
211
12.2 Concentration and
reaction rate
Objective
■ Describe and explain how Why speed up reactions?
concentration affects Tara is a chemist. She works for a company that makes medicines. The
reaction rate company wants to make its medicines as quickly as possible, and as cheaply
as possible. Tara investigates the conditions that speed up reactions that make
medicines.
Questioning reaction rates
Some students ask questions about reaction rates.
Companies employ chemists to tell How can I make In acid reactions,
them how to speed up reactions. reactions faster? what difference does
the concentration of
Junaid Alaur
the acid make?
conical The students decide to investigate Alaur’s question. It is focused. They can get
flask an answer to the question in just one hour.
hydrochloric Planning an investigation
acid
The students decide to investigate the reaction of magnesium with
magnesium stop watch hydrochloric acid. Their teacher gives them the apparatus below.
ribbon The students list the variables in the investigation:
cm3 50 • time for magnesium ribbon to finish reacting
45 • amount of magnesium ribbon
40 • concentration of acid
35 • temperature
30 • volume of acid
25
20 The students decide to change the concentration of acid. They will measure
15 the time for the magnesium ribbon to finish reacting. They will keep the
10 other two variables constant, so that their test is fair.
5
The students wonder how much magnesium ribbon to use. They do some
measuring preliminary work to find out. This involves adding different lengths of
cylinder magnesium ribbon to acids of different concentration. They find the length
of ribbon that reacts with the most and least concentrated acids in a
Apparatus for investigating the sensible time.
effect of acid concentration on
rate of reaction.
212
Rates of reaction
Presenting evidencetime for reaction to finish (s)
The students write their results in a table. Next, they plot the points on a
graph, and draw a line of best fit.
90
80
70
60
50
40
30
20
10
0
0.5 1 1.5 2 2.5
relative acid concentration
The graph shows how reaction time varies with acid concentration.
Considering evidence
The students write a conclusion for their investigation.
The graph shows a correlation between acid concentration and reaction
time. As acid concentration increases, reaction time decreases. This means
that when the acid concentration is higher, the rate of reaction is faster.
The students need to improve their conclusion. They must give a scientific
explanation for the correlation.
Explaining the correlation between concentration If the beaker on the left represents a less
and rate concentrated acid ... then the beaker on
the right represents a more concentrated
The concentration of a solution tells you how much solute is dissolved acid. Water particles are not shown on
in the solvent. The more concentrated an acid solution, the greater the the diagrams. Not to scale.
number of acid particles dissolved in a certain volume of solution.
Substances only react when their particles hit each other, or collide. The
more concentrated an acid, the more frequently its particles collide with
magnesium particles … and the faster the reaction.
1 Explain why the students displayed their results on a line graph, not a bar chart. ● For reactions involving
2 Describe the correlation between acid concentration and reaction rate. solutions, the more
3 Use ideas about particles to explain the correlation you described in question 2. concentrated the solution,
4 A student wonders whether the results would be similar if they used a different acid. the faster the reaction.
Suggest how they could investigate. 213
12.3 Temperature and
reaction rate
Objective
■ Describe and explain how Cooking temperatures
temperature affects reaction Farai and Ibrahim chop potatoes.
rate Ibrahim adds his potatoes to boiling
water, at 100°C. They cook in
12 minutes. Farai adds potatoes The higher the temperature, the faster
to boiling oil, at 200°C. They cook food cooks.
more quickly.
The chemical reactions that happen
when potatoes cook are quicker at
higher temperatures. The reaction
rates are faster. Is this true for other
reactions?
Investigation rates and temperature
Ideas and evidence
Reactions happen when moving particles collide. At higher temperatures,
particles move more quickly, and collide more frequently.
Farai uses this scientific explanation to make a prediction.
Prediction:
The higher the temperature, the more frequently particles collide.
I predict that the higher the temperature, the faster the reaction.
conical Planning an investigation
flask
Sodium thiosulfate solution reacts with hydrochloric acid to make four
sodium thiosulfate products. The word equation summarises the reaction:
solution and dilute paper with cross
hydrochloric acid drawn on it sodium thiosulfate + hydrochloric acid sodium chloride + water + sulfur
dioxide + sulfur
The reaction of sodium thiosulfate
solution with hydrochloric acid The sulfur is formed as a solid. It is insoluble in water, so it makes the
makes solid sulfur. Soon, Farai will reaction mixture cloudy.
not be able to see the cross under
the flask. Farai draws a cross on a piece of paper. He stands a conical flask on the cross.
He pour sodium thiosulfate solution into the flask. Then he adds hydrochloric
acid. He starts the timer.
Gradually, solid sulfur forms. Soon, the mixture is so cloudy that Farai
can no longer see the cross. He does the same experiment using acid at
four different temperatures. He repeats the whole investigation twice
more, to reduce error and make his results more reliable. Will his prediction
be correct?
214
Rates of reaction
Presenting results
Farai writes his results in a table.
Temperature of acid Time to cover cross (seconds)
(°C) 1 2 3 average
20 244 240 242 242
30 119 117 118 118
40 59 61 63 61
50 67 32 30 31
60 13 16 16 15
Farai notices that the first result for 50 °C is very different from the othertime to cover cross (s)
results at this temperature. The result is anomalous. He decides not to include
this result when calculating the average time for 50 °C.
Farai knows that both the variable he changes (temperature) and the variable
he measures (time) are continuous. He decides to draw a line graph. Drawing
a graph makes it easier to spot patterns in results.
300
250
200
150
100
50
0
10 20 30 40 50 60 70
temperature (°C)
Considering evidence
The graph shows a correlation – the higher the temperature, the faster the
reaction. As temperature increases, so does the rate of reaction.
This finding agrees with Farai’s prediction. He is now more confident that the
explanation on which he based his prediction is correct.
1 Describe the correlation between temperature and rate of reaction. ● Increasing temperature
increases reaction rate.
2 Use ideas about particles to explain the correlation between temperature and rate
of reaction. 215
3 Farai wants to investigate whether increasing temperature increases the rate of the reaction
of magnesium with hydrochloric acid. Describe an investigation he could do to find out.
12.4 Surface area and
reaction rate
Objective
■ Describe and explain Flour tragedy
how temperature affects In 1965 in London, England, an
reaction rate explosion at a flour mill killed four
people and injured 31. Why does
Do powders flour explode?
react faster
than bigger lumps of Flour is made up of tiny grains.
solid? In the air, the grains spread out,
as dust. Particles from the air –
including oxygen molecules –
surround the flour grains. Then
someone lights a match. Instantly,
a flour grain catches fire. It lights
the other grains near it. A flame
flashes through the flour cloud.
This is the explosion. Other powders
form explosive mixtures with air,
too, including fine sugar, coal dust,
and sawdust. Flour and other powders can explode in
the laboratory.
Surface area and reaction rate
Making a prediction
Catherine wants to investigate reactions involving powders. She asks
a question.
Catherine decides to investigate the reaction of dilute hydrochloric acid with
calcium carbonate. The equation below summarises the reaction.
calcium carbonate + hydrochloric acid
calcium chloride + carbon dioxide + water
Catherine knows that substances react when their particles collide. In the
reaction above, particles from hydrochloric acid react only with particles on
the surface of a piece of calcium carbonate. Ten grams of calcium carbonate
powder has a bigger surface area than ten grams of calcium carbonate
lumps. This means that the powder has more particles that are available
to react.
Catherine uses this knowledge to make a prediction.
Calcium carbonate powder will react with dilute acid more quickly than big
lumps of calcium carbonate.
216
Obtaining evidence calcium Rates of reaction
carbonate
Catherine sets up the apparatus in the diagram. As carbon dioxide is made, it cotton wool
escapes from the apparatus. The mass of the flask and its contents decreases. conical flask
hydrochloric
Catherine adds a big lump of calcium carbonate to dilute hydrochloric acid. acid
She measures the time for the mass to decrease by 1.0 g.
balance
Next, Catherine adds calcium carbonate powder to dilute hydrochloric acid.
She uses the same mass of calcium carbonate as before. She measures the Apparatus to investigate how
time for the mass to decrease by 1.0 g. surface area affects reaction rate.
Finally, Catherine adds small lumps of calcium carbonate powder to dilute
hydrochloric acid. Again, she keeps the other variables constant. She measures
the time for the mass to decrease by 1.0 g.
Presenting evidence
The table shows Catherine’s results.
Size of calcium carbonate pieces Time for total mass to decrease by 1.0 g (mins)
big lump 10
powder 1
small lumps 5
Catherine wants to draw a graph. This will make it easier to spot patterns
in her results. The variable she changes (the size of the pieces of calcium
carbonate) is discrete. This means she must draw a bar chart.
Considering evidence time for mass to 12
decrease by 1.0 g (minutes)
The bar chart shows that, as surface 10
area increases, the time for the reaction
decreases. Therefore, increasing surface 8
area increases reaction rate.
6
Catherine’s prediction is correct. Increasing
the surface area increases the number 4
of particles available for reaction. Acid
particles collide with solid particles more 2
frequently, so the reaction rate increases.
0 big powder small
lumps lumps
size of pieces of
calcium carbonate
The bar chart shows how surface
area affects reaction time.
1 Identify the variables Catherine needs to control in her investigation. ● Increasing the surface area
of solid reactants increases
2 Describe the correlation between surface area and rate of reaction. reaction rate.
3 Use ideas about particles to explain the correlation between surface area and rate 217
of reaction.
12.5 Catalysts and reaction rate
Objective A natural catalyst
■ Describe and explain how
Sarah chews a piece of bread. She chews it for a long time. After a while, there
catalysts affect reaction rate is a sweet taste in her mouth.
There has been a chemical reaction in Sarah’s mouth. Starch molecules from
Chewing white bread for a long the bread have broken down to form glucose. Glucose is a sugar. The reaction
time makes a substance with a happens very, very slowly on its own.
sweet taste. In our mouths there is a substance that makes the reaction happen more
quickly. This substance is an enzyme called salivary amylase. All enzymes
are examples of catalysts. A catalyst is a substance that speeds up a reaction
without being used up in the reaction.
Another natural catalyst
Hydrogen peroxide is a bleach. It makes paper white. Hydrogen peroxide is
normally diluted with water. It breaks down very slowly to make water and
oxygen gas. The reaction is called a decomposition reaction.
hydrogen peroxide water + oxygen
Amber has a test tube of hydrogen peroxide solution. She adds a small piece
of chicken liver to the solution. It bubbles vigorously. A substance in the liver
catalyses the decomposition reaction. The catalyst is an enzyme called catalase.
It speeds up the reaction without being used up.
Testing for oxygen gas
Amber puts a glowing splint into the foam above the reaction mixture. The
glowing splint relights. This shows that the gas produced in the reaction
is oxygen.
Testing catalysts
Amber wants to test some other substances. Which will be the best catalyst for
the decomposition of hydrogen peroxide? She sets up the apparatus below.
Catalase in liver catalyses the oxygen
decomposition reaction of water
hydrogen peroxide.
catalyst hydrogen
peroxide
Apparatus for measuring the
volume of oxygen produced when
hydrogen peroxide decomposes.
218
Rates of reaction
Amber draws a table for her results.
Name of substance Volume of oxygen gas produced in 1 minute (cm3)
manganese (IV) oxide 25.0
lead (IV) oxide 28.0
iron (III) oxide 0
copper (II) oxide 1.0
zinc oxide 0
hydrogen peroxide only 0
She studies her data, and writes a conclusion.
Manganese (IV) oxide and lead (IV) oxide are the best catalysts for the
decomposition reaction. I know this because they produced the biggest
volumes of oxygen gas in 1 minute.
Iron (III) oxide and zinc oxide do not catalyse the decomposition reaction of
hydrogen peroxide.
How do catalysts work?
Catalysts make it easier for a reaction to start. The decomposition reaction
of hydrogen peroxide happens on the surface of the catalyst powders.
Using catalysts
Catalysts are vital in the chemical industry. They speed reactions up,
meaning that more product is made in a shorter time. For example,
iron catalyses the reaction of hydrogen with nitrogen to make
ammonia. Ammonia makes fertilisers and explosives.
Catalytic converters in car exhaust systems contain metal catalysts
such as platinum, rhodium, and palladium. The metals catalyse
reactions such as the one below, in which poisonous carbon
monoxide is converted to carbon dioxide, which is not poisonous.
carbon monoxide + oxygen carbon dioxide
Catalytic converters in cars convert harmful
gases to less harmful ones.
1 Explain what catalysts do. ● Catalysts speed up reactions
2 Give examples of three catalysts. without themselves being
3 Explain how catalysts speed up reactions. used up in the reaction.
219
Review c Abbas wants to find out how the rate of reaction
changes if he increases the concentration of acid.
12.6
i Name two variables he should keep [2]
1 Abbas investigates the reaction of zinc with the same in his investigation.
hydrochloric acid. He pours 25 cm3 of the acid
into a conical flask. He adds small pieces of zinc. ii Explain why he should keep these [1]
He collects the gas in a syringe. variables the same.
iii Draw a table in which Abbas could
write his results. [1]
2 Arifa investigates the reaction of sodium thiosulfate
solution with hydrochloric acid.
gas One of the products of the reaction is sulfur. This
syringe forms as a solid.
flask As sulfur is made, it hides the cross under the
conical flask. Arifa measures the time taken for
the cross to disappear.
small pieces dilute conical
of zinc hydrochloric flask
acid
a The products of the reaction are zinc chloride
and hydrogen. Write a word equation for
the reaction. [1]
b Abbas measures the volume of gas collected sodium thiosulfate
solution and dilute paper with cross
every minute. He plots a graph of his results. hydrochloric acid drawn on it
90 a Arifa wants to find out how changing the
80 temperature affects the rate of the reaction.
70
volume of gas (cm3) 60 i Name the variable Arifa changes. [1]
50
40 ii Name the variable Arifa measures. [1]
30
20 iii Name three variables Arifa should control. [3]
10
0 b Arifa’s results are in the table.
0 Temperature (°C) Time for cross to disappear (s)
20 1 2 3 average
30
123 4 40 400 403 397 400
time (minutes) 50
60 200 202 198
70
104 100 102 102
i Between which times is the reaction fastest? 47 50 47 48
Choose from the list below. [1] 24 27 27 26
Between 0 and 1 minute. 148 13 13 58
Between 2 and 3 minutes.
Between 3 and 4 minutes. i Suggest why Arifa measures the time
for the cross to disappear three times
ii After how many minutes does the reaction at each temperature. [1]
finish? [1]
ii Calculate the missing average. [1]
iii What is the total volume of gas made in the
investigation? [1] iii Plot Arifa’s results on a graph, and draw
a line of best fit. [1]
220
Rates of reaction
iv Identify the anomalous result in the c Rashid wants to investigate how the size of the
investigation. [1] pieces of calcium carbonate affect the reaction
rate.
v Describe the correlation shown by
the graph. [1] He has three sizes of calcium carbonate pieces –
big lumps, small lumps, and powder.
c Use ideas about particles and collisions
to help you explain the correlation [2] He decides to measure the time taken for 1.0 g
shown by the graph. of gas to be made with each size of calcium
carbonate pieces.
3 Rashid investigates the reaction of hydrochloric
acid with calcium carbonate. i Name the variable he changes. [1]
The equation for the reaction is ii Name the variable he measures. [1]
hydrochloric acid + calcium carbonate iii Name two variables Rashid must [1]
calcium chloride + carbon dioxide + water keep constant.
a Predict which product of the reaction is iv Draw a table for Rashid’s results. [2]
formed as a gas.
[1] v Rashid finds that the powder reacts most
quickly.
b Rashid sets up the apparatus below.
calcium cotton wool Which of the reasons below best explains
carbonate why?
conical flask
For a certain mass of calcium carbonate,
hydrochloric the powder has the smallest surface area.
acid For a certain mass of calcium carbonate,
the powder has the biggest surface area.
balance For a certain mass of calcium carbonate,
the powder has the highest concentration.
i Rashid predicts that, as the reaction 4 The equation below shows the products when
progresses, the mass of the reaction mixture hydrogen peroxide decomposes:
in the flask will decrease.
hydrogen peroxide water + oxygen
Which of the reasons below best explains
why the mass decreases? Manganese(iv) oxide catalyses the reaction.
The product that is formed as a gas a What is a catalyst? [2]
dissolves in the reaction mixture.
The product that is formed as a gas b Salama wants to investigate the effects
escapes into the air. of different catalysts on the reaction.
The product that is formed as a gas is She measures the volume of oxygen gas
made up of atoms of two elements. [1] produced in one minute by four different
catalysts. Draw a table for Salama’s
ii Rashid records the mass of the reactant investigation. [2]
mixture every minute. He plots a graph of
his results.
Predict which of the graphs below best
represents Rashid’s results.
ABC
[1]
221
Review CD
Stage 9
1 The diagram shows the sub-atomic particles in an
atom of an element.
a Give the number of sub-atomic particles in a Which electron arrangement is incorrect? [1]
[1]
the nucleus of the atom. [1] b Which two elements are in the same [1]
group of the periodic table?
[3]
c Which element is in period three of [1]
the periodic table?
[2]
4 The table below shows the densities of some [1]
group 2 elements. [2]
b Name the two types of particles found [2] Element Density (g/cm3)
in the nucleus. calcium 1.54
strontium
c Predict which group of the periodic table [1] barium 3.51
the element is in. radium 5.00
2 Three scientists, Geiger, Marsden, and Rutherford, a Plot the data in the table on a bar chart.
fired small positively-charged particles at thin
sheet of gold foil. b Use your bar chart to predict the
The diagram shows the paths of some of the particles. density of strontium.
gold foil 5 The tables give data for elements in two
groups of the periodic table.
Table A.
Element Boiling point (°C)
lithium 1330
sodium 890
potassium 774
a Explain why some of the particles travelled Table B.
straight through the foil. [1] Element
chlorine
b Give the name of the part of the atom which bromine Boiling point (°C)
causes some particles to change direction. [1] iodine –35
59
c Explain why more particles travel straight [1] 184
through the foil than change direction.
3 The diagrams below show the electron a Use the periodic table to give the group
arrangements of atoms of four elements. numbers of the elements in Table A and
Table B.
AB
b Describe the trend in boiling points for the
elements in Table A.
c Compare the trend you described in part
(b) with the trend in boiling points for the
elements in Table B.
2C22 D
6 Iveta neutralises an acid with an alkali. She d Artem writes a conclusion for his investigation.
records the temperatures of the solutions
before and after the reaction. The temperature change was similar for all the
fuels. I think 1 g of each fuel releases similar
She writes her results in a table. amounts of heat when they burn.
Temperature of acid before reaction (°C) 21 Do you agree with Artem’s conclusion? [2]
23 Explain why, or why not.
Temperature of alkali before reaction (°C) 69
8 Part of the reactivity series is given below.
Maximum temperature reached after
reaction (°C) sodium iron
a Explain how the results show that the calcium lead
neutralisation reaction is exothermic.
[1] magnesium copper
b Name one other type of reaction that zinc gold
is usually exothermic.
[1] a Use the reactivity series to predict which of the
7 Artem investigates the energy given out by four fuels. following pairs of substances will react when
He sets up the apparatus below.
they are heated together. [1]
calcium and zinc oxide
clamp iron and zinc oxide
copper and lead sulfate solution
lead and copper sulfate solution
thermometer b Write word equations for the reactions in [2]
clamp part (a) that you predict will react.
water c Use the reactivity series to help you explain
calorimeter the following:
i Why gold is used to make jewellery. [1]
ii Why water taps are not made from
calcium. [1]
spirit burner iii Sodium is stored under oil. [1]
fuel
9 Name the salts made by the following pairs of
substances.
He measures the temperature change of the water a Copper oxide and hydrochloric acid. [1]
when he burns 1 g of each fuel.
b Magnesium and sulfuric acid. [1]
a Name the variable Artem changes, and the c Zinc and nitric acid. [1]
variable he measures.
[1] 10 Copy and complete the word equations below.
b Name two variables Artem must control [1]
in the investigation. a calcium + water [1]
c Artem obtains the results in the table. b magnesium + oxygen [1]
Temperature Temperature c zinc + hydrochloric acid [1]
before after
Fuel heating (°C) heating (°C) Temperature 11 Zara wants to make zinc chloride. She adds zinc
change (°C) to hydrochloric acid, until a little zinc remains
butanol 20 35 unreacted. Then she filters the mixture.
pentanol 15
hexanol 21 33 a Explain why she filters the mixture. [1]
heptanol 22
22 44 21 b Describe how Zara can make zinc chloride
21 crystals from her zinc chloride solution. [2]
i Calculate the two missing values in [2]
the table.
ii Which fuel heated up the water the most? [1]
223
Reference Choosing apparatus
1 There are many different types of scientific apparatus. The table below shows
what they look like, how to draw them, and what you can use them for.
Apparatus name What it looks like Diagram What you can use it for
test tube
● Heating solids and liquids.
● Mixing substances.
● Small-scale chemical
reactions.
boiling tube ● A boiling tube is a big test
tube. You can use it for
doing the same things as a
test tube.
beaker ● Heating liquids and
conical flask solutions.
filter funnel
● Mixing substances.
● Heating liquids and
solutions.
● Mixing substances.
● To separate solids from
liquids, using filter paper.
evaporating dish ● To evaporate a liquid from
condenser a solution.
224 ● To cool a substance in
the gas state, so that
it condenses to the
liquid state.
stand, clamp, and boss Reference 1: Choosing apparatus
Bunsen burner ● To hold apparatus safely
tripod in place.
gauze
pipette ● To heat the contents of
syringe beakers or test tubes.
spatula
tongs and test tube holders ● To heat solids.
● To support apparatus above
a Bunsen burner.
● To spread out heat from a
Bunsen burner.
● To support apparatus
such as beakers over a
Bunsen burner.
● To transfer liquids or
solutions from one
container to another.
● To transfer liquids and
solutions.
● To measure volumes of
liquids or solutions.
● To transfer solids from one
container to another.
● To hold hot apparatus,
or to hold a test tube in a
hot flame.
225
Reference Working accurately
and safely
2
Using measuring apparatus accurately
cm3 60
100 50 You need to make accurate measurements in science practicals. You will need
to choose the correct measuring instrument, and use it properly.
90
80 Measuring cylinder
70 Measuring cylinders measure volumes of liquids or solutions. A measuring
60 cylinder is better for this job than a beaker because it measures smaller
50 differences in volume.
40 To measure volume:
30 1. Place the measuring cylinder on a flat surface.
20 2. Bend down so that your eyes are level with the surface of liquid.
10 3. Use the scale to read the volume. You need to look at the bottom of the
column curved surface of the liquid. The curved surface is called the meniscus.
of liquid Measuring cylinders measure volume in cubic centimetres, cm3, or millilitres,
ml. One cm3 is the same as one ml.
bulb
The different parts of a Thermometer
The diagram to the left shows an alcohol thermometer. The liquid expands
thermometer. when the bulb is in a hot liquid and moves up the column. The liquid
contracts when the bulb is in a cold liquid.
The temperature of the liquid To measure temperature:
is 95 °C. 1. Look at the scale on the thermometer. Work out the temperature difference
The balance measures mass. represented by each small division.
2. Place the bulb of the thermometer in the liquid.
226 3. Bend down so that your eyes are level with the liquid in the thermometer.
4. Use the scale to read the temperature.
Most thermometers measure temperature in degrees Celsius, °C.
Balance
A balance is used to measure mass. Sometimes you need to find the mass of
something that you can only measure in a container, like liquid in a beaker.
To use a balance to find the mass of liquid in a beaker:
1. Place the empty beaker on the pan. Read its mass.
2. Pour the liquid into the beaker. Read the new mass.
3. Calculate the mass of the liquid like this:
(mass of liquid) = (mass of beaker + liquid) – (mass of beaker)
Balances normally measure mass in grams, g, or kilograms, kg.
Reference 2: Working accurately and safely
Working safely
Hazard symbols
Hazards are the possible dangers linked to using substances or doing
experiments. Hazardous substances display hazard symbols. The table shows
some hazard symbols. It also shows how to reduce risks from each hazard.
Hazard symbol What it means Reduce risks from this hazard by…
Corrosive – The substance attacks and destroys living ● Wearing eye protection
tissue, such as skin and eyes. ● Avoiding contact with the skin
Irritant – The substance is not corrosive, but will make ● Wearing eye protection
the skin go red or form blisters. ● Avoiding contact with the skin
Toxic – Can cause death, for example, if it is swallowed ● Wearing eye protection
or breathed in. ● Wearing gloves
● Wearing a mask, or using the substance in a fume
cupboard
Flammable – Catches fire easily. ● Wearing eye protection
● Keeping away from flames and sparks
Explosive – The substance may explode if it comes into ● Wearing eye protection
contact with a flame or heat. ● Keeping away from flames and sparks
Dangerous to the environment – The substance may ● Taking care with disposal
pollute the environment.
Other hazards
The table does not list all the hazards of doing practical work in science. You
need to follow the guidance below to work safely. Always follow your teacher’s
safety advice, too.
● Take care not to touch hot apparatus, even if it does not look hot.
● Take care not to break glass apparatus – leave it in a safe place on the table,
where it cannot roll off.
● Support apparatus safely. For example, you might need to weigh down a
clamp stand if you are hanging heavy loads from the clamp.
● If you are using an electrical circuit, switch it off before making any change
to the circuit.
● Remember that wires may get hot, even with a low voltage.
● Never connect wires across the terminals of a battery.
● Do not look directly at the Sun, or at a laser beam.
● Wear eye protection – whatever you are doing in the laboratory!
227
Reference Recording results
3 A simple table
Results are easier to understand if they are in a clear table.
Write the name of the X Y Write the name of the
variable you change (units) (units) variable you observe
or compare in box X. If or measure in box Y.
it is something you can If you are measuring
measure, add its units. it, add the right units.
Use one line for each
test you plan to do.
Write the names of any I kept these variables the
variables you control same to make it a fair test:
under the table, and
add their values. e.g. volume of water = 50cm3
Units
It is very important to use the correct units.
°C cm3 grams centimetres
100
degrees 12345
celsius 90 10 20 30 40 50
MS minutes 80 millimetres
and seconds
70
60 cubic
50 centimetres
40
30
20
10
The units of The units of The units of The units of The units of
temperature time volume mass length
include include include include include
degrees celsius (ºC). seconds (s), cubic centimetres (cm3) grams (g), millimetres (mm),
minutes (min), kilograms (kg), centimetres (cm),
228 and
and cubic decimetres (dm3). and metres (m),
hours (hr). tonnes (t).
and
kilometres (km).
Making results reliable, and reducing error
You should always try to repeat observations or measurements. Never rely on a
single result. If repeat results are similar, they are more reliable. Repeating
results also helps to reduce error. If the results keep changing, try to find
out why. It could be a mistake, or there might be another variable you need
to control.
When you collect similar measurements, you should calculate their
average value.
Reference 3: Recording results
Three students find the time it takes to draw a table. Jamil takes 75 seconds,
Abiola takes 35 seconds, and Karis takes 73 seconds.
Abiola’s result is anomalous because it is very different from the others. Jamil
and Karis find out why. Abiola’s table is very messy. She did not use a ruler.
They decide to leave it out of the average.
average time = sum of the measurements = 75 + 73 = 148 = 74 seconds
number of measurements 2 2
A table for repeat results
X Y Draw boxes for three
(units) (units) results for each test,
and an average value.
123 average If a result looks
anomalous, repeat it.
A table for results that need to be calculated
Some variables can’t be measured. They need to be calculated from two
different results. Do all the calculations before you calculate an average value.
X Result 1 Result 2 Y Average Draw boxes for three
(units) (units) (units) (units) (units) sets of measurements,
three calculated values,
and an average. If a
result looks anomalous,
repeat it.
229
Reference Displaying results
4 Drawing a bar chart
Three students timed how long they spent doing homework. The results are in
the table.
A bar chart makes results like these easier to compare.
Students Time spent on homework (hours)
Deepak 2
Jamila 4.5
Kasim 1
6
Write the name of time spent on homework (hours) 4
the variable you observe 2
or measure on the Y axis,
and add the correct units.
Leave gaps
between the bars
Write the Y values on 0 Write the name of the
the lines, evenly spaced. Deepak Jemila Kasim variable you change
Only start at zero if your students or compare on the X axis
values are close to zero.
Write the X values
in the spaces.
Categoric or continuous
If the values of the variable you change (X)
are words, then X is a categoric or discrete
variable. You can only draw a bar chart for
this type of variable.
Variables like shoe size are also categoric
variables. They are numbers, but there are
no inbetween sizes.
Other variables are continuous variables.
Their values can be any number. Height is a
continuous variable and so is temperature.
If the variables you change and measure are both continuous variables,
display the results on a line graph or scatter plot.
230
Reference 4: Displaying results
Drawing a line graph
A line graph makes it easier to see the relationship between two continuous
variables – the variable you change or compare and the variable you observe
or measure.
The number of points
above and below the line of
best fit should be equal.
100
Write the name height of plant (cm) 80 Draw a smooth line of best fit.
of the variable you It could be straight or curved.
observe or measure
on the Y axis, and 60
add the correct units.
40 Use a neat pencil
Make sure the 20 cross for each point.
numbers on each axis
0 Write the name of
are evenly spaced. 0 2 4 6 8 10 the variable you
time (weeks) change or compare
on the X axis, and
Write the X values add the correct units.
on the lines.
Drawing a scatter graph
A scatter graph shows whether there is a correlation between two continuous
variables. In the graph below, all the points lie close to a straight line. That
means there is a correlation between them.
A correlation does not mean that one variable affects the other one. Something
else could make them both increase or decrease at the same time.
60
58 Add a straight
line of best fit.
arm length (cm) 56
54 Use a neat pencil
52 cross for each point.
Make sure the numbers 50
are evenly spaced. 48
140 150 160 170
height (cm)
Start just below Choose intervals that make
your lowest value. the graph easy to plot.
231
Reference Analysing results: charts
and diagrams
5
Describe the pattern. time to get Charts and diagrams help you to analyse results. They show differences
(e.g. A is bigger than B) to school (mins)between results clearly. The flow chart shows you how to analyse results.
Use the numbers to Here is a bar chart to show how long it takes three students to get to school.
compare results.
35
(e.g. A is three times bigger than B) 30
25
Suggest a reason using 20
scientific knowledge. 15
(e.g. This is because...) 10
5
0
Jemila Deepak Kasim
students
The first stage of analysing your results is to describe the pattern.
“Deepak takes the shortest time to get to school. Kasim takes the longest time to get
to school.”
The next stage it to use the numbers on the y-axis of the bar chart to
make comparisons.
“Deepak takes 10 minutes to get to school, but Kasim takes 30 minutes. Kasim takes three
times longer.
Finally, suggest reasons for any differences that you have found.
“This could be because Kasim lives further away or because Deepak walks more quickly.”
When you do an experiment, use scientific knowledge to explain differences
between results. Here are some examples of scientific reasons.
I think that the I think that the plant near the I think that the
powdered sugar dissolved window grew more quickly than shoe on the carpet needed
faster than the normal sugar the plant away from the window a bigger force to move it than the shoe
because the pieces were much because there was more sunlight on the wooden floor because there was
more friction between the shoe
smaller. there.
and the carpet.
232
Reference 5: Analysing results: charts and diagrams
Analysing results – line graphs Describe the pattern by saying
what happens to B as A increases.
Line graphs show correlations between continuous variables. When you have
plotted the points on a line graph, draw a line of best fit. Then analyse the (e.g. As A increases B increases)
graph. The flow chart on the right shows how to do this.
In the graphs below the line of best fit is shown, but not the points. Choose pairs of values to illustrate
B BB the pattern and compare them.
(e.g. When A is 3, B is 2, and
when A is 6 B is 4 so doubling A
will double B)
Suggest a reason using
scientific knowledge.
(e.g. This is because...)
A A A B
In both these graphs, if A In both these graphs, if A If A increases B does not Graph 1
increases then B increases. increases then B decreases. change. B
2
These graphs show a These graphs show a This graph shows 1
positive correlation. negative correlation. no correlation. 0
On some graphs the line of best fit is a straight line. You can say ‘B changes Graph 2 2 A
by the same amount for each increase in A’. The blue line in Graph 1 shows B 4A
that B increases by the same amount for each change in A. The red line
shows that B decreases by the same amount for each change in A. You
can choose values to illustrate this. Graph 2 on the right shows how.
A graph with a positive correlation where the line of best fit is a straight line
that starts at zero is a special case. In this case B is directly proportional to
A. You can say ‘if A doubles then B will also double’. (See Graph 3.) You can
choose values to illustrate this.
A graph that has a curved shape with a negative correlation may show that
B is inversely proportional to A. Choose pairs of values. If you get the same
number every time you multiply A by B then B is inversely proportional to A.
This is the same as saying ‘if you double A then B will halve’. (See Graph 4.)
You can choose values to illustrate this.
BB straight line
starts Graph 3 A
at zero
A A A
B
Here B increases, or decreases as A increases Here B increases, or decreases as A increases 233
BUT does so more quickly as A gets bigger. BUT does so more slowly as a gets bigger.
When you have described the pattern in your results, try to use scientific
knowledge to explain the pattern.
Graph 4
Reference Detecting gases
6 Hydrogen gas
To find out whether a reaction in a test tube has produced hydrogen gas:
1. Collect a small quantity of gas by holding an empty test tube upside down
over the top of the test tube containing the reaction mixture.
2. Place a lighted splint in the gas.
3. If the splint goes out with a squeaky pop, hydrogen gas is present.
Oxygen gas
To find out whether a reaction in a test tube has produced oxygen gas:
1. Collect a small quantity of gas by holding an empty test tube upside down
over the top of the test tube containing the reaction mixture.
2. Place a glowing splint in the gas.
3. If the splint relights, oxygen gas is present.
Carbon dioxide gas
To find out whether a reaction in a test tube has produced carbon dioxide gas:
● Bubble the gas through limewater solution.
● If the limewater solution turns milky or cloudy, carbon dioxide is present.
teat pipette
glass tube
reaction
mixture
limewater limewater
reaction
mixture
The diagrams show two ways of bubbling gases through limewater.
234
Reference
7
1.0 4 Periodic Table
H
hydrogen He The periodic table shows all of the elements in order of the number of protons
1 they have in their nucleus – the proton number.
helium
79 11 12 14 16 19 2
Li Be B CNO 20
lithium beryllium boron carbon nitrogen oxygen F
34 5678 Ne
fluorine
23 24 27 28 31 32 9 neon
Na Mg AI Si P S 10
sodium magnesium aluminium silicon phosphorus sulfur 35.5 40
11 12 13 14 15 16
CI Ar
39 40 45 48 51 52 55 56 59 59 63.5 65 70 73 75 79
K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se chlorine argon
potassium calcium scandium titanium vanadium chromium manganese iron cobalt nickel copper zinc gallium germanium arsenic selenium 17 18
19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 80 84
85.5 88 89 91 93 96 (98) 101 103 106 108 112 115 119 122 128 Br Kr
Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te
rubidium strontium yttrium zirconium niobium molybdenum technetium ruthenium rhodium palladium silver cadmium indium tin antimony tellurium bromine krypton
37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 35 36
127 131
133 137 139 178.5 181 184 186 190 192 195 197 201 204 207 209 210
Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po I Xe
caesium barium lanthanum hafnium tantalum tungsten rhenium osmium iridium platinum gold mercury thallium lead bismuth polonium
55 56 57 72 73 74 75 76 77 78 79 80 81 82 83 84 iodine xenon
53 54
222
(210)
Rn
At
radon
astatine 86
85
(223) (226) (227) (261) (262) (266) (264) (277) (268) (271) (272)
Fr Ra Ac Rf Db Sg Bh Hs Mt Ds Rg
francium radium actinium rutherfordium dubnium seaborgium bohrium hassium meitnerium Darmstadtium roentgenium
87 88 89 104 105 106 107 108 109 110 111
Note: This periodic table does not include all the elements.
235
Glossary Bunsen burner a piece of Combustion a burning reaction,
apparatus that burns gas to heat in which a substance reacts quickly
Acid a solution with a pH of less things in the laboratory with oxygen and gives out light
than 7 and heat
Burning a reaction in which
Acidic a substance is acidic if its a substance reacts quickly with Compaction when sediments are
pH is less than 7 oxygen and gives out light and squashed together to make new
heat. Also called combustion. rocks by the weight of layers above
Acid rain rain that is more acidic
than usual because substances such Carbonates a group of Compound a substance made up
as sulfur dioxide are dissolved in it compounds which make carbon of atoms of two or more elements
dioxide when they react with chemically joined together
Air pressure the force exerted by acid. Carbonates are made up
air particles when they collide with of atoms of carbon, oxygen, Concentrated a solution that
1 m2 of a surface and a metal element. There contains a lot of solute dissolved in
are 3 oxygen atoms for every very little solvent
Alkali a solution with a pH of 1 carbon atom.
more than 7 Concentration the amount of a
Catalyst a substance which substance that is dissolved in a
Alkaline a solution is alkaline if speeds up a reaction without certain volume of a solution
its pH is more than 7 itself being used up in the
reaction Condense when a substance
Alloy a mixture of two or more changes from the gas state to the
elements, at least one of which is Cementation the ‘gluing together’ liquid state at the boiling point of
a metal of particles of sediment by different the substance or below
minerals
Anomalous an odd result, or Continuous variable a variable
piece of data, that does not fit the Change of state the change that which can have any value within
pattern of results happens when a substance changes a range, for example time,
from one state to another, for temperature, length, mass
Atom the smallest particle of an example from solid to liquid or
element which can exist from gas to liquid Contracts gets smaller
Balance an instrument for Chemical reaction an event Correlation a link between two
measuring mass which creates new substances and variables
which is not easy to reverse
Basalt an igneous rock formed Corrosion a reaction that
from liquid rock that cooled quickly. Chemical symbols letters which happens on the surface of a
Its crystals are relatively small. represent elements (usually one or metal when the metal reacts with
two letters) which are understood substances from the air or water
Base metal oxides are bases. in all languages. Each element has around it. Corrosion reactions
They neutralise acids. its own chemical symbol. happen slowly.
Beaker a container that you Chemical weathering the Corrosive a corrosive substance
can use for mixing, reacting, and breaking up or wearing down of destroys living tissue
heating chemicals rocks by the action of chemicals
such as those in rainwater Creative thinking thinking in a
Best-fit line a smooth line on a new way
graph that travels through or very Chloride a compound that is
close to as many plotted points made up of chlorine and one other Crude oil a thick black liquid
as possible element, for example sodium formed underground, or under the
chloride, NaCl sea, from the remains of plants
Biological weathering the and animals that died millions of
breaking up or wearing down of a Chromatogram a record obtained years ago. Crude oil is used to make
rock by the action of living things from chromatography fuels, such as petrol and diesel, and
many plastics.
Boil when a substance changes Chromatography a method of
from the liquid state to the gas separating mixtures of liquids Crust the outer layer of the Earth.
state at its boiling point It is made up of different types of
Clay soil in clay soil, at least 40% rock, and is thinner than the other
Boiling point the temperature of the rock fragments are clay layers of the Earth.
at which a substance in the liquid
state boils and changes to the Claystone an example of a Crystal a substance in the solid
gas state. Every substance has its sedimentary rock state with its atoms arranged in a
own boiling point. regular pattern, for example salt
Collision when a particle bumps and diamond
Brittle a substance is brittle if it into another particle, or the inside
breaks easily when you hit it with of its container Data measurements taken from
a hammer an investigation
236
Decanting carefully pouring off a Energy levels electrons in atoms Glossary
liquid from a mixture of the liquid occupy energy levels. Energy levels
with a solid, in which the solid has are also called shells, or orbits. Fractional distillation heating
settled to the bottom; or pouring off a liquid mixture to separate it
the top liquid from two liquids that Erosion the processes of into fractions with different
have settled one on top of the other. weathering and transportation boiling points
together make up erosion
Density the mass of a substance in Freeze when a substance
a certain volume. A substance with a Evaporation when a substance changes from the liquid state to
high density feels heavy for its size. changes from the liquid state to the the solid state
gas state. Evaporation can happen
Deposition the settling of at any temperature. Freezing point the temperature
sediments that have moved away at which a substance changes
from their original rock Evidence observations or from the liquid state to the solid
measurements that support a state. Each substance has its own
Diffusion the spreading out and scientific explanation freezing point.
mixing of particles from areas
with many particles to areas with Exothermic change a change Fuel a store of energy which
fewer particles in which energy is released to the burns to release useful heat, for
surroundings. example coal and diesel
Discrete variable a variable
whose values are words, or whose Expand get bigger Gas a fluid with no fixed volume
values can only have certain that takes the shape of its container
numerical values Explanation a scientific idea
that explains evidence and which Gas pressure the force exerted
Diesel a fuel separated from scientists have developed using by gas particles when they collide
crude oil creative thought with 1 m2 of a surface
Dilute a solution that contains Fair test an investigation in which Geologist a scientist who
very little solvent dissolved in a lot all the variables are kept constant studies the origin, structure, and
of solvent except the variable which the composition of the Earth
investigator changes
Dissolve when a substance (the Global warming the gradual
solute) mixes with a liquid (the Filter a way of removing pieces of increase in the Earth’s average
solvent) to make a solution solid that are mixed with a liquid surface temperature
or solution by pouring through
Displacement reaction a reaction filter paper Gneiss an example of a
in which a more reactive metal metamorphic rock
displaces a less reactive metal Filtration separating pieces of
from a compound of the less solid from a mixture with a liquid Granite an igneous rock formed
reactive metal or solution from liquid rock that cooled slowly.
Its crystals are relatively large.
Distillation a method of separating Fluid a substance that has no
a solvent from a solution, for fixed shape and that flows to fill a Greenhouse gases gases that
example water from salty water container or space contribute to climate change, for
example carbon dioxide
Ductile a material is ductile if it Fossil the remains or traces of a
can be pulled into wires plant or animal that lived many Group the elements in one vertical
years ago column of the periodic table
Electric balance an instrument
for measuring mass that is Fossil fuels fuels made from Group 1 elements the elements
powered by electricity the remains of animals and in the left vertical column of the
plants that died millions of years periodic table
Electron a sub-atomic particle ago, for example coal, oil, and
that moves around the outer parts natural gas Group 2 elements the elements in
of an atom. It has a single negative the vertical column that is second
charge. Its relative mass is 1/1840. Formula (plural formulae) a from the left of the periodic table
Element a substance consisting of formula uses symbols and Group 7 elements the elements
atoms of only one type. It cannot in the vertical column that is
be split into new substances. numbers to show the relative second from the right of the
periodic table. They are also called
Empirical question a question number of atoms of each element the halogens.
that can be answered scientifically,
by collecting evidence and using in a compound. For example, the Halogens the elements in the
creative thought vertical column that is second
formula of water is Hm2aOd.eTuhpisof from the right of the periodic table.
Endothermic change a change in shows that water is They are also called the group 7
which energy is taken in from the elements.
surroundings. atoms of hydrogen and oxygen,
Hard a material is hard if it is
strongly joined together. In a difficult to scratch
sample of water, there are two Hazard a possible source of danger
hydrogen atoms for every one
oxygen atom.
237
Hazard symbols warning Mantle the layer of the Earth that Neutral a substance or solution
symbols on chemicals that show is beneath the crust. It is solid but with a pH of 7 which is neither
what harm they might cause if not can flow very slowly. It goes down acidic nor alkaline
handled properly almost halfway to the centre of
the Earth. Neutralise to add acid or alkali
Hummus decayed plant and to a solution to make a solution
animal matter in the soil Marble a metamorphic rock of pH 7
formed from limestone
Hydroxide a compound made up Neutralisation the process of
of a metal, hydrogen, and oxygen. Mass the amount of matter in making a solution neutral
something
Index fossil a fossil type that Non-metals elements that are
identifies the geological time Materials the different types of not metals. They do not conduct
period in which a rock was formed. matter that things are made of electricity. They are to the right of
Every time period has its own the stepped line of the periodic table.
index fossil. Matter stuff that takes up space
and has mass Non-porous a non-porous
Inner core the solid iron and material does not have small gaps
nickel at the centre of Earth Measuring cylinder a piece of containing gases or liquids. Water
apparatus that measures volumes cannot soak into a porous material.
Insoluble a substance that does of liquids or solutions
not dissolve in a solvent Nucleon number the number
Melt when a substances changes of protons and neutrons in the
Inverse correlation a link from the solid state to the liquid nucleus of an atom. It is also called
between two variables in which state mass number.
when one variable increases, the
other variable decreases Melting point the temperature Nucleus (plural nuclei) the
at which a substance changes from central part of an atom. Most of the
Igneous rock rock made when the solid to liquid state. Every mass of an atom is in its nucleus.
liquid rock (called magma below substance has its own melting The nuclei of all elements are made
the surface of the Earth, and lava point. up of protons and neutrons, except
above the surface of the Earth) for the nuclei of most hydrogen
cooled and solidified Meniscus the surface of a liquid atoms which are made up of one
proton only.
Isotope atoms of the same element Metalloid an element with
which have different numbers of properties that are between those Neutron a sub-atomic particle
neutrons are called isotopes of metals and non-metals found in the nucleus of an atom.
It has no electric charge. Its
Joule (J) the unit of energy Metals elements which are good relative mass is 1, the same as the
conductors of heat and electricity. mass of a proton.
Kilogram unit of mass Most elements are metals. They are
to the left of the stepped line on the Observations the results of
Kilojoule (kJ) 1000 joules periodic table. looking carefully at something
and noticing properties or changes
Lava hot liquid rock that is on – or Metamorphic rock a type of rock
above – the surface of the Earth formed by the action of heat and/ Oil a fossil fuel formed from sea
or pressure on sedimentary or creatures over millions of years
Limestone an example of a type igneous rock
of sedimentary rock. It is mainly Orbits electrons in atoms occupy
calcium carbonate Minerals substances that occur orbits. They are also called energy
naturally. They are usually made levels, or shells.
Liquid a fluid with a fixed up of crystals.
volume that takes the shape of Ore a rock that contains natural
its container Mixture a mixture contains two minerals from which useful
or more elements or compounds substances, for example metals,
Litmus indicator an indicator mixed together. The substances in can be extracted
which tells you if a substance is a mixture are not chemically joined
acidic or alkaline. If a substance is together. Outer core the liquid iron and
alkaline, it makes red litmus become nickel between the Earth’s mantle
blue. If a substance is acidic, it Molecule a particle of a substance and inner core
makes blue litmus paper red. made from two or more atoms that
are strongly joined together Oxide a compound of oxygen with
Loam in a loam soil the rock another element
fragments are 40% sand, 40% silt, Mudstone a type of sedimentary
and 20% clay rock Palaeontologists scientists that
study fossils and use evidence from
Magma hot liquid rock that is Natural polymer a polymer that them – and creative thinking – to
beneath the Earth’s surface exists naturally, often made by understand the history of life on
plants or animals Earth
Malleable a material is malleable
if it can be hammered into shape
without cracking
238
Particle theory a theory that uses Radiometric dating this uses the Glossary
ideas about particles to explain natural decay of particles in a rock
how matter behaves to measure the age of a rock Secondary source a source such
as a book or the Internet which
Particles tiny pieces of matter Range the difference between the provides evidence or data that you
from which everything is made biggest value and the smallest value have not collected yourself
in a series of data
Period a horizontal row of the Sedimentary (rock) rock made
periodic table Rate of reaction how fast a from sediments joined together by
reaction is. The faster a reaction, pressure or chemicals
Periodic table an arrangement the greater its rate.
of all the elements in order of Sedimentation the settling of
increasing number of protons Reactants the starting materials, solid particles that were mixed
(proton number). In the periodic or substances that react together, in with a liquid
table, the elements are grouped a chemical reaction
with those that have similar Sediments pieces of matter which
properties. Reactivity series a list of metals have settled to the bottom of a liquid
placed in order of their reactivity
pH a way of measuring how acidic Semiconductor a material is
or alkaline a solution is Risk the chance of damage or a semi-conductor if it conducts
injury from a hazard electricity less well than conductors,
pH scale the range of levels of but better than insulators
acidity and alkalinity Rock cycle the rock cycle explains
how rocks change and are recycled Semi-metal an element with
Physical weathering the breaking into new rocks over millions of years properties that are between those
up or wearing down of rocks, for of metals and non-metals
example, by the effects of changing Rusting the corrosion reaction of
temperature iron. Oxygen and water are needed Shells electrons in atoms occupy
for iron to rust. The product of shells. Shells are also called energy
Polymer a substance with large the reaction – rust – is hydrated levels, or orbits
molecules made up of atoms joined iron oxide.
together in long chains Slate a metamorphic rock made
Sacrificial protection putting a from mudstone
Porous a porous material has more reactive metal in contact with
small gaps which may contain a less reactive one so that the more Solid a state of matter in which
gases or liquids. Water can soak reactive metal corrodes. The more the substance has a fixed shape
into a porous material. reactive metal is sacrificed to and volume
protect the less reactive one.
Predict suggest what you think Solubility the maximum mass of
will happen Salt a compound in which the solute that can dissolve in 100 g
hydrogen atom of an acid has been of solvent
Prediction a suggestion of what replaced by a metal atom. Salts
will happen may be formed in neutralisation Soluble a substance is soluble in
reactions or in reactions of acids a solvent if it can dissolve in that
Preliminary work observations with metals or metal oxides. solvent
or measurements done at the
start of an investigation to work Sandstone an example of a type Solute a substance which dissolves
out appropriate values for control of sedimentary rock in a solvent to make a solution
variables
Sandy soil in sandy soil, most of Solution a mixture of solvent
Primary data data collected the rock fragments are sand and solute, in which the solute has
directly for a particular dissolved.
investigation Saturated solution a solution
in which no more solute can Solvent in a solution, the liquid in
Products the new substances dissolve which the solute is dissolved
that are made in a chemical
reaction Scientific journal a collection of Sonorous a material is sonorous if
papers, written by scientists, which it makes a ringing sound when hit
Property a characteristic of a describe their work and which have
substance; how it behaves been carefully checked by other States of matter most substances
scientists can exist as a solid, a liquid, and a
Proton a tiny sub-atomic particle gas. These are the states of matter.
with a positive charge. Protons Scientific model an idea that
are found in the nuclei of atoms. explains observations, and that Stirring rod a rod, usually made
The relative mass of a proton is 1, you can use to make predictions. from glass, that is used to stir
the same as that of a neutron. A scientific model of an object or chemicals
phenomenon is simpler than the
Proton number the number real thing. Strata the layers of sedimentary
of protons in the nucleus of an rocks and soils that have built up
atom over time
Strong a material is strong if a
large force is needed to break it
239
Sub-atomic particles the Synthetic polymer a polymer Uplift uplift happens when huge
particles that make up an atom, made by people and machines in forces from inside the Earth push
including protons, neutrons, and factories or science laboratories rocks upwards. The process makes
electrons mountains.
Temperature a measure of how
Sublimation when a substance hot something is Variable a quantity which can
changes from the solid state change in an investigation, for
directly to the gas state Thermite reaction the example time, temperature, length,
displacement reaction of iron oxide mass
Sublime when a substance with aluminium. The products are
changes from the solid state iron and aluminium oxide. The Vulcanologist a scientist who
directly to the gas state reaction releases a great amount of studies volcanoes
energy as heat and light.
Sulfate a compound that Weathering weathering breaks
includes atoms of the elements Thermometer an instrument you up all types of rock into smaller
sulfur and oxygen. There are can use to measure temperature pieces, called sediments
four oxygen atoms for every one
sulfur atom. Transportation the processes by Word equation a word equation
which sediments of rock that have summarises a chemical reaction in
Symbol equation an equation in been removed from their original words. It shows the reactants and
which the reactants and products rock by weathering are moved products. The arrow means ‘react
are represented by their formulae. away from the original rock to make’.
It gives the relative amounts of the
substances in the reaction, and Universal Indicator (UI) a solution
their states. that changes colour to show the pH
of the solution it is mixed with
240
Index balances 21, 226
bar charts 22, 33, 230, 232
acid rain 47 barium 158, 159
acids 42, 43 basalt 54, 55
bases 112
metal oxides 134 beakers 21
neutralisation 46–7, 134 bendiness 105
pH scale 44–5 beryllium 158
reactions of metals with acids 186–7 body 128
Adewusi, Steve 125
aeroplanes 34 body chemicals 128
air 66, 116 mineral deficiency 129
air pressure 87, 88–9 vitamins 129
al-Biruni 85 Bohr, Niels 151
Alemseged, Zeresnay 74 boiling 10, 16
alkalis 43 boiling point 11
neutralisation 134 air pressure 87
pH scale 44–5 effects of altitude 12–13
alloys 34 explaining boiling points 16
explaining alloy properties 35 Group 1 elements 156
aluminium 99, 101, 137, 195 measuring boiling point 11
thermite reaction 193 metals 28, 105
aluminium oxide 112 non-metals 30, 105
ammonium chloride 178–9 boron 155
ammonium nitrate 178 Bose, Satyendra Nath 166
ammonium sulfate 206–7 Boyle, Robert 88–9, 95
animals 71 Bradbury, Howard 125
anomalous results 91, 229 Brandt, Hennig 98
apparatus 21, 44–5, 224–5 brittleness 30, 37, 105
measuring apparatus 226 bromine 160
working safely 227 bronze 35, 98
argon 105 Brown, Robert 83
Aristotle 52 Bunsen burners 21
atoms 94, 100 burning reactions 133, 182–3, 196, 197
1932: a new model 146
atoms and elements 94 caesium 99
electronic structure 152 calcite 60
ideas and evidence 95 calcium 106, 158, 159, 188
imagining atoms 94
isotopes 155 calcium and water 184
metals 104–5 calculations 90, 109, 127
models of atoms 146
Nagaoka’s Saturn model 149 calculating average value 228–9
non-metals 104–5 carbon 27, 31, 133, 155
nucleon number 154–5
proton number 154 extracting metals 194, 195
protons, electrons, and the periodic table carbon dioxide 107, 110, 174
152–3 testing for carbon dioxide gas 234
Rutherford’s model 151 carbon monoxide 107, 110
solid atoms 146 carbonates 113
sub-atomic particles 146–7 cassava 125
Thomson’s plum pudding model 149, catalysts 218
150–1 catalytic converters 219
why do atoms have no electrical charge? 147 how do catalysts work? 219
Australopithecus afarensis 75 testing catalysts 218–19
average value 228–9 using catalysts 219
cathode rays 148–9
Cavendish, Henry 99
cementation 57, 59
Chadwick, James 151
changes of state 10, 81
energy 16–17
241
charcoal 98 correlations 91, 231
chemical reactions 132 correlation between concentration and
rate 213
acid reactions 134 inverse correlations 129
combustion reactions 133 line graphs 233
corrosion 136–7
energy changes 170–1 corrosion 136
flame tests 140 copper corrosion 136
making a salt 134–5 iron corrosion 136
making ammonium sulfate 206–7 not all metals corrode 137
making copper sulfate 202–3 predicting and preventing corrosion 189
making magnesium chloride 200–1 preventing corrosion 137
making sodium chloride 204–5 silver corrosion 136–7
metal hydroxide colours 140–1
rates of reaction 210–11 corrosives 42
signs of chemical reactions 132 cotton 36, 39
word equations 134 creative thinking 88
chlorides 114–15 crude oil 122–3
chlorine 155, 160 crystals 60, 61, 200
chromatography 124
chromatography of ink 124 crystal size 55
chromatography of spinach 124 cylinders 21
using chromatography 124–5
chromium 112 Dalton, John 95, 100
Chu Hsi 62 data 19
citric acid 171
clay 36, 67 interpreting data from secondary sources 102–3,
claystone 56 123, 127, 162–3
collision 86
combustion 133, 174 making conclusions from data in tables 32
compaction 57, 59 observations that do not fit a pattern 33
comparisons 232 decanting 118
compounds 106–7 Democritus 97
carbonates 113 density 28
formulae of oxides and hydroxides 113 calculating density 84
hydroxides 112 explaining density 85
imagining compounds 107 Group 1 elements 157
interpreting formulae 111 using density 85
making a compound 108–9 what is density? 84
mixtures 116–17 deposition 57, 59
naming compounds 110–11 diamond 31
oxides 112 diesel 174, 175
sulfates 113 diffusion 82
writing formulae 111 diffusion and particle size and mass 82
compression 9 diffusion and temperature 82
concentration 45 diffusion diffusion on gases, liquids and solids 83
concentration and reaction rates dilution 45
dinosaurs 71
212–13 displacement reactions 192
condensation 11 displacing metals from metal oxides 192–3
conduction 28, 37 thermite reaction 193
contraction 9 dissolving 18, 171
copper 27, 98, 100, 158, 184, 185 endothermic processes 178–9
distillation 121, 122
copper corrosion 136 crude oil 122–3
displacement reactions 192 ethanol and water 122
zinc and copper oxide 196 ductility 28
copper sulfate 100, 113, 120
copper sulfate crystals 120, 200 Earth 52, 72
making copper sulfate 134–5, 202–3 cooling calculations 72
core temperature 53
242 crust 52, 54, 103
flat Earth model 52 exothermic reactions 170–1 Index
fossils 71, 72 expansion 9
geological time scale 73 extension 33 243
hollow Earth model 52 eye protection 227
inner and outer core 53
mantle 52 fair tests 20
radioactive dating 73 fertilisers 206–7
relative dating from rock strata 72
structure 52–3 fertiliser production 207
Einstein, Albert 166 filtration 118
electricity 28, 37 flame tests 140
electrolysis 195 flexibility 37
electrons 146–7, 151 flour mill explosion 216
electrons in atoms 152 fluorine 160
finding electrons 148–9 food energy 176–7
Group 1 elements 157 formulae 111
periodic table 152–3 fossils 70
elements 26, 94
compounds 106–7 fossil record 71
discoveries 98–9 human fossils 74–5
early ideas about elements 98 index fossil 73
electronic structure 152–3 life on Earth 71
Group 1 elements 156–7 fractional distillation 122–3
Group 2 elements 158–9 freezing 15
Group 7 elements 160–1 explaining freezing 17
mixtures 116–17 freezing point 15
organising the elements 100–1 fuels 170, 172–3, 174
platinum 97 convenience and safety 175
symbols for the elements 96 fuel production 174–5
symbols in the periodic table 96–7 how much heat? 174
tantalum 97 products of combustion 174
writing chemical symbols 96 which fuel is best? 174, 175
emeralds 158 fungi 202
endothermic reactions 170, 171
dissolving ammonium nitrate 178 gabbro 55
energy 16–17 gallium 101
chemical reactions 170–1 gas detection 234
energy in food 176–7 gas pressure 86
energy levels 152
erosion 57, 59, 63 air pressure 87
ethanol 122, 174, 175 air pressure and boiling point 87
evaporation 10, 16, 170 how does temperature affect
copper sulfate crystals 120
lithium compounds 121 gas pressure? 86
sodium chloride 120 gas state 8, 80
evidence 12, 20
air pressure 88–9 diffusion through gases 83
bar chart or line graph? 22 gas to liquid 11
chromatography 125 Geiger, Hans 150, 151
doing calculations 90, 109, 127 gemstones 85
drawing a line graph 22 geology 62–3
evidence for moving particles 83 geological time scale 73
identifying anomalous results 91 germanium 101
identifying trends and patterns 91 glass 36
organising the elements 100–1 gneiss 61
presenting evidence 90 Goel, Sudha 163
presenting evidence in a table 22 gold 29, 98, 137, 184, 185, 188
separating gold from sand 126, 194
grains of rock 56
granite 54, 55
graphite 31
gravity 72
greenhouse gases 174 considering evidence 90–1, 109, 139
Group 1 elements 156 considering variables 20
correlations 91
electron arrangements 157 endothermic processes 178–9
properties and patterns 156–7 fuels 172–3
reactions with water 157 hazards and risks 108–9, 135, 179
Group 2 elements 158 identifying evidence to collect 20
reactions with acid 159 making a compound 108–9
reactions with water 159 making observations 21
Group 7 elements 160 making predictions 20
group trends 160 neutralisation 48–9
reactions 161 nickel 190–1
planning an investigation 90, 138–9
haematite 112 presenting evidence 90, 139
Halley, Edmond 52 rates of reaction and concentration 212–13
halogens 160 rates of reaction and surface area 216–17
hardness 28, 37 rates of reaction and temperature 214–15
hazards 108–9, 135, 179 reactions of metals with acids 186–7
sea salt 114–15
acid reactions 186 separating mixtures 118–19
hazard symbols 227 testing ideas 20, 89
heat 28, 37 turning ideas into questions to test 138
exothermic and endothermic reactions 170–1 iodine 100, 105, 160
fuels 170, 172–3, 174 iodine deficiency 129
helium 27, 30, 105, 147 iron 27, 29, 98, 116–17, 188, 194, 195
helium atom structure 166 burning iron filings 182
Higgs boson 166–7 displacement reactions 192, 192
Higgs, Peter 166 iron corrosion 136
Hittorf, Johann 148 iron oxide 112
Homo floresiensis 75 iron sulfide 117
Hooke, Robert 89 isotopes 155
human fossils 74–5
footprints in Laetoli 75 Jabir Ibn Hayyan 43
Selam 74 James Webb Space Telescope 158
tiny humans 75
Toumaï 74–5 krypton 105
humus 66
Hutton, James 63 laboratory acids 42
hydrochloric acid 159, 170–1 Large Hadron Collider (LHC) 166–7
reactions with metals 186–7 lava 64
hydrogen 27, 152, 154, 185 lead 84, 188, 195
fuel 174, 175 Lehmann, Inge 53
testing for hydrogen 187, 234 Leucippus 97
hydrogen peroxide 218–19 limestone 54, 57
hydroxides 112, 185
formulae of oxides and hydroxides 113 marble from limestone 60
line graphs 22, 33
Ibn Sina 62
ice 85, 170 analysing results 233
identifying chemicals 140–1 drawing a line graph 23, 231
igneous rocks 54–5 scales 23
liquid state 8, 80
non-porous rock 55 diffusion through liquids 83
rock cycle 63 liquid to gas 10
indicators 44 liquid to solid 15
making an indicator 44–5 lithium 121, 147, 152, 157, 188
testing the indicator 45 burning lithium 197
information 19 corrosion 189
investigations 20 lithium and water 184
burning reactions in metals 182–3 litmus indicator 44
choosing and using apparatus 21 loam 67
244
Index
magma 54, 60, 63, 64, 65 distillation 121
magnesium 99, 133, 152, 154, 158, 159, 188, 195 evaporation 120–1
filtering 118
burning magnesium 182, 196 fractional distillation 122–3
displacement reactions 192 molecules 105, 107
magnesium bombs 182 mudstone 56, 61
magnesium chloride 200–1
magnesium ribbon in water 184 Nagaoka, Hantaro 149
malleability 28 neon 30, 105
manganese chloride crystals 200 neutralisation 46, 134, 170–1
marble 54
marble from limestone 60 acid rain 47
Marsden, Ernest 150, 151 investigating 48–9
mass number 154 soil pH 46–7
materials 26 neutrons 146–7
properties 36–7 nickel 99, 190–1
measuring vessels 21, 226 nickel nitrate crystals 200
melting 14, 170 nitrogen 27, 99
explaining melting 16–17 non-metals 26, 27, 30–1, 32
melting point 14 atom arrangements 104–5
Group 1 elements 156 boiling and melting points 30
metals 28, 105 compounds of a metal and a non-metal 110
non-metals 30, 105 compounds of a metal, non-metal, and oxygen 110
using melting points 14 compounds of non-metals 110
Mendeleev, Dmitri 100–1, 103 periodic table 104
meniscus 226 solid non-metal elements 30
mercury 27, 88–9 nucleon number 154–5
metal hydroxide colours 140–1 nucleus 146, 147, 149
metalloids 31 inside the nucleus 151
metals 26, 27, 28, 32 Rutherford’s model 151
alloys 34–5 testing the plum pudding model 150–1
atom arrangements 104–5
burning metals 182 observations 21
comparing burning reactions 182–3 neutralisation 49
compounds of a metal and a non-metal 110 observations that do not fit a pattern 33
compounds of a metal, non-metal, and oxygen 110
conduction of heat and electricity 28, 32 orbits 152
displacement reactions 192–3 ores 126–7
metals under water 184–5
not all metals corrode 137 extracting gold 194
order of reactivity of metals with water 185 extracting iron 194
particle mass 85 extracting lead 195
periodic table 104 oxides 112, 185
reactions of metals with acids 186–7 acids with metal oxides 134
reactions of metals with water 184–5 displacing metals from metal oxides 192–3
reactivity series 188–9 formulae of oxides and hydroxides 113
separating metals from their ores 126–7, 194–5 making oxides 112
sonority 28 metal or non-metal? 112
state and appearance 28 using oxides 112
using metals 29 oxygen 27, 30, 99, 106, 154
metamorphic rocks 54, 55, 60–1 changes of state 80–1
recognising metamorphic rocks 61 compounds 107
rock cycle 63 compounds of a metal, non-metal, and oxygen 110
methane 175 oxygen molecules 105
minerals 55 reactions of metals with oxygen 182–3
mineral deficiency 129 testing for oxygen gas 218, 234
mixtures 116–17
chromatography 124–5 palaeontologists 71
decanting 118 particles 8–9
closeness of particles 85
discovering the nucleus 150–1
245
particles (continued) organising the elements 100–1
dissolving 18 rock cycle 62–3
evidence for moving particles 83 scientific explanation 13
forces between particles 16 turning ideas into questions to test 138
particle mass 85
sub-atomic particles 146–7 radiometric dating 73, 74
radium 158
patterns 33, 91, 156, 211, 232 rates of reaction 210
periodic table 26–7, 96–7, 235
catalysts 218–19
Group 1 elements 156–7 concentration and reaction rates 212–13
Group 2 elements 158–9 correlation between concentration and rate 213
Group 7 elements 160–1 following a reaction 210–11
groups 164 surface area 216–17
interpreting data from secondary sources 102–3 temperature 214–15
Mendeleev, Dmitri 100–1, 103 reactants 133
periodic trends 164–5 reactivity series 188
periods 164 corrosion 189
pH scale 44 extracting metals from their ores 194–5
choosing and using apparatus 44–5 nickel 190–1
concentrated or dilute 45 periodic table 188
soil pH 46–7 reliability 228
using indicators 44 results 211
phosphorus 30, 98, 106 analysis 232–3
plants 71 anomalous results 91, 229
plastics 36, 38–9 categoric or continuous 230
platinum 97, 137, 188 drawing a bar chart 230
polymers 38–9 drawing a line graph 231
natural polymers 39 drawing a scatter graph 231
polypropene 38 making results reliable and reducing error 228–9
polythene 38 tables 228
potassium 27, 157, 188 tables for repeat results 229
potassium manganate 83 tables for results that need to be calculated 229
Prasad, Ananda 94 units 228
precipitates 140–1 review questions 78–9, 130–1, 142–3, 144–5, 168–9,
predictions 20, 88
volcanic eruptions 65 222–3
preliminary work 182 acids 50–1
pressure 86 alkalis 50–1
Priestley, Joseph 99 chemical reactions 180–1
products 133 elements 40–1
properties 26 geology 76–7
alloys 35 making salts 208–9
compounds 106–7 particles 24–5
Group 1 elements 156 rates of reaction 220–1
igneous rocks 55 reactivity series 198–9
materials 36–7 rhenium 99
metals 28, 104 risks 108–9, 135, 179
non-metals 30, 104 acid reactions 186
sedimentary rocks 56 rock cycle 63
soil 67 geological theory 62–3
protons 146–7, 151, 152 rock fragments 66
proton number 154 rock strata 72, 73
pure substance 14 rubber 36
PVC (polyvinyl chloride) 39 rubidium 99
rubies 112
quartz 55 Rubinstein, Claudia 71
questions 12–13 rust 136, 137, 138–9, 210
Rutherford, Daniel 99
collecting evidence 12 Rutherford, Ernest 150–1
empirical questions 88, 100, 125
246
sacrificial protection 189 Solar System 72 Index
Salam, Mohammed Abdus 166 solid state 8, 81
salts 200 247
diffusion in solids 83
making a salt 134–5 solid to liquid 14
making ammonium sulfate 206–7 solubility 18
making copper sulfate 134–5, 202–3 solutes 18
making magnesium chloride 200–1 solutions 18
making sodium chloride 204–5 saturated solutions 18
sand 112, 126, 194 solvents 18
sandstone 56 sonority 28
sandy soil 67 spectroscopes 99
Saturn 149 states of matter 8, 80–1
scandium 101 steam 84
scatter graphs 231 steel 34, 137
scientific journals 19 stiffness 37
scientific models 52 stirring rods 21
models for the atom 146, 149, 150–1 strength 28, 36, 105
scientific reasons 232 strontium 158, 159
secondary sources 19 sub-atomic particles 146–7
chlorinating water 162–3 how scientists work 166–7
crude oil 123 sublimation 15
periodic table 102–3 sugar cane 175
tin production 127 separating sugar crystals from
sedimentary rocks 54, 55, 56
identifying 56 sugar cane 201
porous rock 56 sulfates 113
rock cycle 63 sulfur 30, 96, 98, 100, 116–17
sedimentary rock formation 57, 58–9 sulfuric acid 42
transportation 59 Sun 72
weathering 58–9 surface area and rates of reaction 216–17
sediments 58 symbols 96–7
semi-metals 31
semiconductors 31 state symbols 197
Sharma, Archana 166 symbol equations 196–7
Sharma, Ritesh 163 synthetic polymers 39
shells 152
silicon 27, 31 tables 22
silicon dioxide 112 recording results 228, 229
silk 39
silver 27, 184, 185, 188 Tacke, Ida 99
silver corrosion 136–7 Taj Mahal, India 47
sisal 36 tantalum 97
slate 61 technetium 99
Smith, William 72, 73 teeth 106
sodium 157, 188, 195 temperature 82, 86
burning 182, 183
sodium chloride 106, 114–15, 120, 170–1 Earth’s core temperature 53
making sodium chloride 204–5 rates of reaction 214–15
sodium hydrogencarbonate 171 thermite reaction 193
sodium hydroxide 43 thermometers 21, 226
soil 66 Thomson, John 148–9, 150
soil air content 68 Thomson, William 72
soil colour 69 tin 126–7, 184, 185
soil drainage 67 Torricelli, Evangelista 88
soil pH 46–7, 68–9 transportation 57, 59
soil texture 67 Traube, Moritz 162
soil types 66–7 trends 91, 156
soil water content 68 trihalomethanes (THMs) 162
units 228
Universal Indicator 44
uplift 63
variables 20, 230, 231 reactions of metals with water 184–5
verdigris 136 water absorption 37
vitamins 129 weathering 57, 58
biological weathering 59
vitamin A 125 chemical weathering 58
volcanoes 64 physical weathering 58
word equations 134
benefits of volcanoes 65 World Health Organisation 125, 162
predicting eruptions 65
xenon 105
water 66, 107
chlorinating water 162–3 Zeno 97
closeness of particles 85 zinc 94, 98, 137, 184, 188, 189, 195
ethanol and water 122
Group 1 elements 157 zinc and copper oxide 196
Group 2 elements 159
248
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Complete Chemistry for Cambridge Secondary 1
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