Science 10

Chapter

10 Some Gases
Henry Cavendish
He is known for the discovery of hydrogen and
measuring the earth's density, etc.
Estimated Periods: 7 (5T+2P)

Objectives

At the end of the lesson, students will be able to:
• explain the lab preparation of carbon dioxide and ammonia gas;
• explain the properties and uses of carbon dioxide and ammonia gas.

Carbon dioxide

Molecular formula - CO2
Molecular weight - 44 amu
Nature of bonding: Covalent bonds
Volume in atmosphere: 0.03%
Freezing point: -78°C

8p 12p 8p

8n 12n 8n

Molecular structure of CO2
Carbon dioxide is a compound gas. It was first prepared by Van
Helmond in 1630 AD and its properties were studied in detail by
Lavoisier.

Occurrence

Carbon dioxide occurs free as well as in combined state in nature. In
free state, it is present in atmosphere in about 0.03% by volume. It
is released into the atmosphere through burning of fuels, respiration
by plants and animals, forest fire, etc. It is found in the form of
compounds such as carbonates, bicarbonate, etc. More concentration
of CO2 is found in caves, mines, deep well, etc because it is heavier
than air.

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General methods of preparation
1. Carbon dioxide is produced by burning hydrocarbons with excess of oxygen.

CH4 + 2O2 burning → CO2 + 2H2O + heat

2C2H6 + 7O2 burning → 4CO2 + 6H2O + heat
2. Carbon dioxide is formed when carbon burns in air with excess of oxygen.

C + O2 → CO2 + heat
3. Carbonates and bicarbonates of metals such as calcium,

magnesium, etc, react with dilute acid to produce carbon dioxide.

CaCO3 + 2HCl → CaCl2 + H2O + CO2
Na2CO3 + 2HCl → 2NaCl + H2O + CO2
Mg(HCO3)2 + 2HCl → MgCl2 + 2H2O + 2CO2
4. Carbon dioxide is produced in large amount by heating limestone.

CaCO3 → CaO + CO2

Laboratory preparation of carbon dioxide

Principle
Carbon dioxide gas is prepared in the laboratory by the action of
dilute hydrochloric acid on calcium carbonate.

CaCO3 + 2HCl → CaCl2 + H2O + CO2
In this reaction, dilute sulphuric acid cannot be used in place of dilute
hydrochloric acid because calcium sulphate formed after reaction
covers the remaining part of marble and prevents the further reaction.

Apparatus required
Woulfe's bottle, thistle funnel, delivery tube, gas jar, cork, match
stick, litmus paper etc.

Chemicals required
1. Calcium carbonate (CaCO3)
2. Dilute hydrochloric acid (HCl)

Procedure
1. Place some pieces of marble in Woulfe's bottle.
2. Connect a thistle funnel and delivery tube with the Woulfe's
bottle using a cork as shown in the figure.

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dil.HCl Delivery tube
cork

woulfe's Gas jar
bottle

Lime stone Carbon dioxide
gas

Laboratory preparation of carbon dioxide gas

3. Pour dilute hydrochloric acid through thistle funnel until it
covers the marble pieces and lower end of the thistle funnel.

4. The chemical reaction between hydrochloric acid and marble
pieces produces carbon dioxide gas.

5. This gas passes through delivery tube and is collected in the
gas jar by upward displacement of air.

Carbon dioxide gas is collected in the gas jar by upward displacement
of air because it is heavier than air. In this process, the cork should
be tightly fitted with the round bottom flask otherwise the gas can
escape and no gas is collected in the gas jar.

Precautions

1. The apparatus should be air tight.
2. The end of thistle funnel should be dipped in the solution

otherwise the CO2 gas can escape through the thistle funnel.
3. The end of delivery tube should not touch the solution within

Woulfe's bottle. If the delivery tube is dipped in the solution,
no gas can travel through the delivery tube. So, the collection
of excess gas in the Woulfe's bottle can cause explosion.

Test of carbon dioxide gas

1. When a moist blue litmus paper is inserted into the jar
containing the gas, the blue litmus paper turns into red. It
is because CO2 combines with H2O of moist litmus paper to
form an acid, which turns blue litmus into red.

2. When a burning match stick is brought near the mouth of
gas jar, the burning match stick extinguishes. It proves that
the gas jar contains carbon dioxide gas.

3. When carbon dioxide is passed through lime water (calcium

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hydroxide), the lime water turns milky white due to the
formation of insoluble calcium carbonate (CaCO3). This
proves that the gas is CO2.
4. When a burning magnesium ribbon is lowered into a jar
containing CO2 gas, the magnesium-ribbon continues to burn
forming magnesium oxide (grey dust) and carbon (black).

Manufacture of carbon dioxides gas

Carbon dioxide gas is manufactured in industrial scale by heating
calcium carbonate (limestone or marble) in a furnace. Calcium oxide
(quick lime) is another useful substance produced in this reaction.

CaCO3 ∆ → CaO + CO2 ↑

(limestone) (quicklime)

When calcium oxide reacts with water, it produces calcium hydroxide,
which is also known as slaked lime or lime water.

CaO + H2O → Ca (OH)2

(Slaked lime or lime water)

Properties of carbon dioxide

Physical properties
1. It is colourless, odourless and tasteless gas.
2. It dissolves sparingly in water.
3. It turns moist blue litmus paper into red.
4. It is heavier than air.
5. Carbon dioxide can be liquefied to a colourless liquid at 0°C
under the pressure of 40 atmospheres.
6. Carbon dioxide can be solidified by cooling it below -78°C or
applying pressure of 70 atmospheres at room temperature.
The solid form of CO2 is known as dry ice. It is called dry ice
because it melts without wetting the other articles like paper,
clothes etc. Dry ice is used in refrigerators to preserve foods.
7. It is neither combustible nor the supporter of combustion.

Chemical properties

1. When carbon dioxide is dissolved in water, it produces
carbonic acid. lt is a weak acid.

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CO2 + H2O → H2CO3

Carbonic acid

Fact &Reason

Carbon dioxide turns moist blue litmus to red, why?

Carbon dioxide reacts with water and form carbonic acid which turns blue litmus

to red.

2. When carbon dioxide is passed through lime water for a short
time, the lime water turns milky. It is due to the formation of
insoluble calcium carbonate.

CO2 + Ca (OH)2 → CaCO3 + H2O
Calcium carbonate (milky white)

If carbon dioxide is passed through the mixture for a long time, the
milky white colour disappears due to the formation of soluble calcium
bicarbonate.

CaCO3 + H2O + CO2 → Ca(HCO3)2

Calcium bicarbonate

3. Carbon dioxide is neither combustible nor the supporter of
combustion. But a burning magnesium ribbon continues to
burn in the atmosphere of carbon dioxide gas with dazzling
light. This reaction produces white powder of magnesium
oxide and black particles of carbon.

2Mg + CO2 → 2MgO + C

Magnesium oxide Carbon black

4. Ammonia reacts with carbon dioxide at about 150°C under

high pressure to produce urea.

2NH3 + CO2 1500C NH2 — CO — NH2 + H2O
Pressure

Urea

5. When carbon dioxide is heated with red hot coke at 900°C,
carbon monoxide is produced.

CO2 + C 900°C → 2CO

6. Green plants convert solar energy into chemical energy in
the form glucose and oxygen.

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6CO2 + 6H2O Sunlight C6H12O6 + 6O2
Chlorophyll Glucose



7. Carbon dioxide reacts with NaOH or KOH solution to produce
carbonate salt.

2NaOH + CO2 → Na2CO3 + H2O

Sodium carbonate

Fact &Reason

Water becomes sour when carbon dioxide is passed into it, why?

Water reacts with carbon dioxide to form carbonic acid. Since acid is sour in taste,

water becomes sour when carbon dioxide is passed into it.

Uses of carbon dioxide

1. It is used in the manufacture of soft drinks like soda water,
coca cola, beer etc,

2. Solid carbon dioxide (dry ice) is used as refrigerant to preserve
fruits, fish, meat etc.

3. It is used in the manufacture of fertilizers (like urea), washing
soda (sodium carbonate).

4. It is used in fire extinguishers.
5. It is used in the purification of sugarcane juice. The process

of purifying sugarcane juice using CO2 is called carbonation.
6. Green plants use carbon dioxide for making food during

photosynthesis.
7. A mixture of gases containing 10 – 15 per cent oxygen and

carbon dioxide is called carbogen. It is used in artificial
respiration of pneumonia patients.

Fire extinguisher

Fire extinguisher is a protective device which produces carbon dioxide
to extinguish fire in emergency conditions.
The fire extinguisher consists of a metallic vessel containing sodium
bicarbonate or sodium carbonate and a bottle of sulphuric acid. The
glass bottle of sulphuric acid is fitted inside the vessel in such a way
that it can be broken easily when the knob is pressed down. Sodium
bicarbonate is filled in the cylindrical glass bottle.

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Knob

Glass
vessel

NaHCO3 Conc.
solution H2SO4

Nozzle Cylinder

Fire extinguisher

When the knob is pressed down or the cylinder is dropped on the
ground, the glass bottle breaks, whereby conc. H2SO4 and NaHCO3
solution get mixed with each other. The acid reacts with NaHCO3
and produces CO2 which comes out from the nozzle.

2NaHCO3 + H2SO4 → Na2SO4 + 2H2O + 2CO2

Na2CO3 + H2SO4 → Na2SO4 + H2O + CO2

Thus produced CO2 extinguishes the fire.

Carbon dioxide gas is heavier than air and hence occupies the lower
most layer in the atmosphere. When carbon dioxide is supplied over
the burning objects, it displaces air (oxygen) and covers the burning
objects as that by a blanket. Thus, the fire gets extinguished due to
the lack of oxygen.

Fact &Reason

Which property of carbon dioxide helps it to extinguish fire?
Carbon dioxide is heavier than air and is non combustible. This property of carbon
dioxide helps it to extinguish fire.

Ammonia

Molecular formula : NH3
Molecular weight : 17
Nature of bonding : Covalent bonds
Ammonia is a compound gas which consists of one atom of nitrogen
and three atoms of hydrogen. Lavoisier prepared ammonia for

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the first time by heating ammonium chloride (Sal ammoniac) and
calcium hydroxide. But its composition was established by Berthecol
and Davy.

1p

7p
7n

1p 1p

Molecular structure of ammonia

Occurrence

Ammonia occurs free as well as in combined state. In free state, it is
present in air near the places where nitrogenous organic compounds
are decaying. In combined state, it is found as different ammonium
salts like, ammonium phosphate, ammonium chloride, ammonium
sulphate, etc.

General methods of preparation

1. By heating ammonium salts

Ammonium sulphate, ammonium carbonate, etc decompose on
heating to produce ammonia.

(NH4)2SO4 ∆ → 2NH3 + H2SO4
Ammonium sulphate

(NH4)2CO3 ∆ → 2NH3 + H2O + CO2
Ammonium carbonate

2. By heating ammonium salts with strong base

When an ammonium salt is heated with strong alkali solution,
ammonia is produced.

NH4Cl + KOH ∆ → KCl + H2O + NH3↑

Ammonium chloride Potassium hydroxide

(NH4)2SO4 + 2NaOH ∆ → Na2SO4 + 2H2O + 2NH3↑
Ammonium sulphate sodium hydroxide

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Laboratory preparation of ammonia gas

Principle

Ammonia gas is prepared in laboratory by heating the mixture of
finely powdered and dry ammonium chloride and calcium hydroxide
(slaked lime) in the ratio 2:1.

2NH4Cl + Ca(OH)2 ∆ → CaCl2 + 2H2O + 2NH3↑
Ammonium chloride Calcium hydroxide

Thus prepared gas is passed through lime tower to obtain pure
ammonia.

Apparatus required

Hard glass test tube, delivery tube, cork, stand, burner, gas jar, red
litmus paper, etc.

Chemicals required

Ammonium chloride (NH4Cl)
Calcium hydroxide [Ca(OH)2]

NH4Cl+Ca(OH)2 Ammonia gas Gas jar
Delivery tube

Hard glass CaO Stand
Lime tower
test tube

Burner Stand

Laboratory preparation of ammonia

Procedure

1. Crush the dry solid form of ammonium chloride and calcium
hydroxide separately into very fine powder and mix them in
the ratio 2:1 by mass.

2. Place the mixture in a hard glass test tube and clamp the
test tube on a stand in an inclined position.

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3. Fit a delivery tube in a cork and insert the cork into the hard
glass test tube.

4. Insert the free end of delivery tube in to a lime tower in order
to get pure ammonia which in turn is fitted to dry gas jar.

5. Heat the mixture with the flame of burner.
6. Heat initiates the reaction and ammonia gas is produced. It

is collected in the gas jar by downward displacement of air.
Ammonia is collected by downward displacement of air because
it is lighter than air. Ammonia gas is not collected by downward
displacement of water because it is highly soluble in water. Ammonia
dissolves in water forming ammonium hydroxide.

NH3 + H2O → NH4OH

Ammonium hydroxide

Fact &Reason

Why is ammonia collected by downward displacement of air?

Ammonia is lighter than air and is highly soluble in water. Due to these properties,

ammonia is collected by downward displacement of air.

The steam produced after the reaction should be liquefied and
collected at the upper part of test tube. If not collected at the upper
part the droplets may fall back to the bottom of test tube and cause
cracking of it. Hence, the hard glass test tube is clamped in the stand
in slanted position to protect from cracking.

Fact &Reason

Why is lime tower used to prepare ammonia gas?
Lime tower absorbs moisture from ammonia. Thus, dry ammonia gas can be
obtained when lime tower is used.

Precautions

1. The apparatus should be made air tight.
2. The hard glass test tube should be clamped in the stand in an

inclined position to prevent it from cracking.
3. The reagents as well as the gas jar should be dry.

Tests of ammonia

1. Ammonia has a characteristic pungent smell. It can be
identified with the help of its pungent odour.

2. When a moist red litmus paper is inserted in the jar containing
the gas, the litmus paper turns blue.

3. When a glass rod dipped in hydrochloric acid (HCl) is brought

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in contact of ammonia gas. It forms white fume of ammonium
chloride (NH4Cl).

Fact &Reason

Ammonia turns red litmus to blue, why?
Ammonia reacts with water to form ammonium hydroxide which is an alkali.
Since alkali turns red litmus to blue, ammonia turns red litmus to blue.

Manufacture of ammonia gas

Ammonia gas is manufactured in large scale by Haber's process. In
this process, a mixture of hydrogen and nitrogen in the ratio of 3:1
by volume is heated to about 450°C under the pressure of 200-900
atmosphere. Finely divided iron is used as catalyst and a molybdenum
(Mo) is used as promoter in the reaction.

Some metal oxides such as Al2O3, K2O, CaO or MgO can also be used
as promoter in place of molybdenum in Haber's process.

N2 + 3H2 4500C, 200-900 atm 2NH3 + heat
Fe+Mo

The reaction is reversible and exothermic.

Conditions required for Haber's process
1. Temperature of about 4500C and high pressure of about 200-
900 atmosphere should be maintained.
2. Finely powdered iron as catalyst and Molybdenum or metal
oxide as a promoter should be used.
3. Large amount of nitrogen and hydrogen should be used.

Properties of ammonia

Physical properties
1. It is a colourless and tasteless gas with pungent smell. It
causes eye irritation.
2. It is lighter than air.
3. It turns moist red litmus paper into blue.
4. It is neither combustible nor the supporter of combustion.
5. It is highly soluble in water.
6. It liquefies at -33.4°C and solidifies at -78°C.

Chemical properties

1. Ammonia dissolves in water to give ammonium hydroxide
(ammonia solution).

NH3 + H2O → NH4OH

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2. Ammonia reacts with acids to produce ammonium salts.

NH3 + HCl → NH4Cl

2NH3 + H2SO4 → (NH4)2SO4

NH3 + HNO3 → NH4NO3

3. Ammonium hydroxide (ammonia solution) reacts with acid to
give salt and water.

2NH4OH + H2SO4 → (NH4)2SO4 + 2H2O

4. When ammonia is heated with carbon dioxide at about 150°C
under high pressure, urea is produced. Urea is a fertilizer.

2NH3 + CO2 1500C NH2—CO—NH2 + H2O
Pressure

urea

5. When ammonia is heated with oxygen, it burns with greenish
yellow. This reaction produces nitrogen and water.

4NH3 + 3O2 ∆ → 2N2 + 6H2O

Uses of ammonia

i) It is used in the manufacture of chemical fertilizers like
ammonium nitrate, ammonium phosphate, urea, etc

ii) Liquid ammonia is used in refrigerators and cold storages.

iii) It is used to develop blue print of maps.

iv) It is used to manufacture different types of industrial products
like nitric acid, plastics, dyes, nylon, rayon, etc

v) It is used to make medicines like ammonium carbonate,
ammonium chloride, etc.

vi) Liquid ammonia is used as laboratory reagent.

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Activity10 .1 To demonstrate that ammonia is highly soluble in water

and basic in nature.

Materials required:

Round bottomed flask, glass tube, beaker, Fountain
stand with clamp etc.
Round
Chemicals required: bottom flask

Ammonia gas, water, phenolphthalein NH3
indicator, etc.

Procedure:

A round bottomed flask filled with

ammonia gas is taken and glass tube Trough

is fitted on it using a cork. The other Water

end of the glass tube is kept within Fountain experiment

the water containing some drops of

phenolphthalein. The glass tube is provided with a jet inside the

round bottomed flask. When ammonia gas it cooled, it creates

low pressure inside the flask, so some water drops rise up in the

flask and form ammonium hydroxide. As a result, more vacuum,

is created inside the flask. Hence, water moves up with pressure

to fill up the vacuum which looks like fountain of pink colour.

Observation:

Water fountain is observed inside the round bottomed flask
for some time. The water (ammonia solution) inside the round
bottomed flask looks pink.

Conclusion:

Ammonia is highly soluble in water. It is basic in nature because
it turns phenolphthalein pink.

Fact &Reason

What happens when ammonia is passed into water containing phenolphthalein?
Ammonia reacts with water to form ammonium hydroxide which is an alkali.
Since alkali turns phenolphthalein into pink, ammonia turns phenolphthalein
into pink.

Learn and Write

1. Carbon dioxide gas is used in a fire extinguisher. Why?

Carbon dioxide gas is heavier than air and hence occupies

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the lowermost layer in the atmosphere. When carbon dioxide
is supplied over the burning objects, it displaces oxygen and
covers the burning objects as that by a blanket. Thus the fire
gets extinguished.

2. Solid carbon dioxide is called dry ice. Why?

Carbon dioxide gets solidified at –78°C. The solid carbon dioxide
melts without wetting other particles like paper, clothes, etc.
Therefore, it is called dry ice.

3. Why are carbon dioxide and ammonia not collected by the
displacement of water?

Both carbon dioxide and ammonia gas are soluble in water.
Therefore, they are not collected in a gas jar by the displacement
of water.

4. Bubbles come out when we open a bottle of soda water. Why?

CO2 gas is dissolved at high pressure in soda water. When we
open a bottle of soda water, the pressure decreases and CO2
comes out in the form of bubbles.

Main points to remember

1. Carbon dioxide gas is prepared in the laboratory by the action of
dilute hydrochloric acid in calcium carbonate.

2. Carbon dioxide is not collected in the gas jar containing water
because it is soluble in water.

3. When carbon dioxide gas is highly compressed or cooled down below
-780C, it is converted into solid form which is known as dry ice.

4. Fire extinguisher is a protective device which produces carbon
dioxide to extinguish fire.

5. In laboratory, ammonia gas is prepared by heating the mixture
of ammonium chloride and slaked lime in the ratio of 2:1.

6. When the mixture of nitrogen and hydrogen in the ratio of 1:3 by
volume is heated in the presence of finely divided iron as catalyst
and a metal oxide as promoter at a temperature of about 4500C
under pressure of about 200-900 atmosphere, ammonia gas is
formed. This process is called Haber's process.

7. The Haber's process involves the reversible and exothermic reaction.
8. Ammonia gas is not collected by downward displacement of

water because it is highly soluble in water.

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Exercise

A. Very short answer questions ( 1 mark)

1. By which property of carbon dioxide it helps to extinguish the

fire?

2. Write the molecular formula of limewater.

3. Name the chemicals that are kept in the fire extinguisher.

4. What is dry ice? Write its one use.

5. Which gas is obtained by reacting limestone and dilute

hydrochloric acid.

6. Name two chemicals which are required to prepare carbon

dioxide gas in laboratory.

7. Which gas is collected in laboratory by downward

displacement of air ?

8. Write any two necessary conditions for the industrial

production of ammonia.

9. Write the balanced chemical equation of laboratory

preparation of ammonia gas.

10. Which gas is made by heating the mixture of ammonium

chloride and calcium hydroxide ?

11. What is promoter ? Give one example.

12. What is Haber's process?

B. Short answer questions ( 2 marks)

1. What happens when carbon dioxide is passed through lime

water for a long time? Write with chemical equation.

2. Write down the equation of the chemical reaction that takes

place inside fire extinguisher.

3. What happens when burning magnesium is introduced to gas

jar of carbon dioxide gas?

4. What happens when ammonium carbonate is heated? Write

with a balanced chemical equation.

5. What happens if ammonia gas is passed into water

containing few drops of phenolphthalein, why?

6. How is urea prepared ? Write with the chemical equation.

7. Write any two precautions that should be adopted during the

laboratory preparation of ammonia gas.

C. Long answer questions ( 3 marks)

1. How is carbon dioxide prepared in industries? Write with a

balanced chemical equation.

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2. Draw a neat and labelled figure showing the laboratory
preparation of carbon dioxide gas.

3. Write down the main uses of carbon dioxide gas.
4. How can we prepare a weak acid from carbon dioxide ? Write

with chemical equation.
5. Write any three uses of ammonia.
6. How is ammonia gas prepared for the industrial

purpose?What is this process called
7. Draw a diagram of laboratory preparation of ammonia gas

and label any four parts. It cannot be collected in the gas jar
by downward displacement of water, why?

D. Very long answer questions ( 4 marks)

1. Study the given diagram and answer the following questions.

i) Which gas is collected in

the gas jar?

ii) Why is the gas jar kept dil.HCl

erect?

iii) This gas cannot be

collected by downward

displacement of water.

Why?

iv) What happens when

this gas is reacted with

potassium hydroxide?

Write the balanced

chemical equation. Lime stone
v) How can you manufacture

urea from the gas

collected in gas jar? Write with balanced chemical

equation.

2. What happens when

i) Carbon dioxide is passed into the lime water for a while ?

ii) Carbon dioxide is passed into the lime water for long

time.

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3. Study the given
diagram and answer NH4Cl+Ca(OH)2
the following
questions.
i) Which gas is
collected in gas
jar?
ii) Why is lime tower
used to collect the
gas?
iii) What happens
when this gas is
passed in water? Write chemical reaction.
iv) Which coloured litmus paper is used to identify such gas?
v) Why is this gas collected in inverted gas jar?

Project Work

Take some lime powder from the market. Add about 2 spoonfuls of
lime powder into a liter of clean water in a trough and stir the mixture
well to prepare lime water. Take a straw or a thin pipe to blow air into
the lime water from your mouth. What will you observe? Explain your
observation with reasons.

Glossary

• Dazzling : very bright so that it is difficult to look at
• Extinguish : to put out fire
• Pungent : having a strong repulsive smell or taste
• Nozzle : syringe, plunger, a narrow pointed opening
• Fountain : spray, spout, jet
• Reagent : a substance taking part in a chemical reaction

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Chapter

11 Metals
Georgius Agricola

He is known as the pioneer in mineralogy.

Estimated Periods: 8 (7T+1P)

Objectives

At the end of the lesson, students will be able to:
• explain the main metals (iron, aluminium, copper, gold, silver) present in the

nature;

• identify and explain the physical and chemical properties of those metals;

• explain the uses of those metals.

Metals are the electropositive solid elements which are good conductors
of heat and electricity. All metals (except mercury) are solid at ordinary
temperature. They are malleable and ductile. Malleability is the
property of metals due to which they can be converted into thin sheet
by hammering whereas ductility means the property of metals to be
drawn into wire. The metals are sonorous. They have high melting
and boiling points. Metals have metallic luster.
The non-metals occur in solid, liquid and gas state. Non-metals
are the electronegative elements which are bad conductors of heat
and electricity. The non-metals do not have metallic luster except
graphite and iodine. They are not malleable and ductile.
The elements which have the properties intermediate between
metals and non-metals are called metalloids. For example, silicon,
arsenic, antimony, germanium, etc. The metalloids have following
characteristics.

a. They are poor conductors of heat and electricity.
b. They have metallic luster.
c. They are not malleable and ductile in general.

Minerals and ores

Minerals are the naturally occurring substances which contain
metals in the form of compounds with impurities. All minerals
are not suitable to extract metals because they may contain very
less amount of metals. Clay (Al2O3, 2SiO2 .2H2O), Cuprite (Cu2O),
horn silver (AgCl), cryolite (Na3Al F6), feldspar (K Al Si3O8) etc. are
minerals.

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The naturally occurring minerals from which metals can be extracted
profitably are called ores. Thus, every ore is mineral but every mineral
is not an ore. For example, Cuprite (Cu2O) is an ore of copper, horn
silver (AgCl) is an ore of silver, magnetite (Fe3O4) is an ore of iron,
etc. They are minerals too.

Difference between minerals and ores:

Minerals Ores

1. Metal may be present 1. Metal is present in comparatively
in more or less amount more amount in ores.
in minerals.

2. All minerals are not 2. Those minerals from which metals
suitable to extract can be extracted are called ores.
metals.

3. All mineral are not ores. 3. All ores are minerals.

Examples: clay, cryolite, Examples: haematite, siderite,
bauxite, feldspar, etc. bauxite, etc.

Metallurgy

The branch of science which deals with the extraction of metal from
the ores and manufacture of metal products is called metallurgy. An
ore may contain a large amount of sand, soil and rocky materials
called gangue. The process of removal of gangue from an ore is called
concentration of ore. There are different steps in the metallurgical
processes. They are crushing of one, pulverization, calcination,
roasting, reduction, refining, etc.

Some important metals

Iron, copper, aluminium, silver and gold are very useful metal.
The occurrence, extraction, properties and uses of these metals are
discussed below:

Iron

Symbol : Fe
Atomic number : 26
Atomic weight : 56
Valency : 2, 3

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Position in the periodic table : Period: 4, Group: VIII, d-block or
transition element
Colour : grey white

Electronic configuration:

Shell K L MN
No. of electrons 2 8 14 2
1s2, 2s22p6, 3s23p6, 4s2, 3d6
Sub-shells

Occurrence

Iron is a reactive metal and is not found in native state. When a
metal exists in free state, it is said to be in native state. It occurs only
in the combined state. It can be found in animal body and in the rocks
as ore. The chief ores of irons are:

1 Haematite Fe2O3
2. Magnetite Fe3O4
3. Siderite FeCO3
4. Limonite Fe2O3.3H2O
5. Iron pyrite Fe2S2

Properties of Iron

Physical properties
1. Iron is a shiny grey coloured metal.
2. It melts at about 15000C and boils at about 25000C.
3. It is a good conductor of heat and electricity.
4. Its specific gravity is 7.86.
5. Iron becomes non-magnetic above 7700C.

Uses
1. It is used in the manufacture of rods, wires, pipes, nuts and
bolts, nails, etc.
2. It is used for making household utensils.
3. It is used in making building, bridges, vehicles, etc.
4. It is used to make different types of instruments and weapons.
5. It is used in the manufacture of steel.

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Aluminium

Symbol : Al

Atomic number : 13

Atomic weight : 27

Valency : 3

Position in the periodic table : Period 3, Group IIIA, P-block
element

Colour : Silvery white

Electronic configuration:

Shells K LM
No. of electrons 2 83
1s2, 2s22p6, 3s23p1
Sub-shells

Occurrence

It is the most abundant metal on the earth's crust. It is always found
in combined state in nature and it does not occur in native state. The
main ores of aluminium are:

1. Bauxite Al2O3. 2H2O
2. Felspar K(AlSi3O8)
3. Cryolite Na3Al F6

Fact &Reason

Utensils made of aluminium are not affected by air and water though it is reactive
metal, why?
Aluminium reacts with air to form thin and strong layer of aluminium oxide due
to which it is not affected by air and water though it is reactive metal. Hence,
utensils made of aluminium are not affected by air and water though it is reactive
metal.

Properties

Physical properties
1. It is a silvery white and light metal.
2. It is highly malleable and ductile.
3. It is good conductor of heat and electricity,
4. Its melting point is 6600C and boiling point is 18000C.
5. Its specific gravity is 2.7.

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Uses

1. Aluminium is a rusting resistant light metal. So, it is used for
making body of aeroplane, cars, buses, etc.

2. Aluminium foil is used for wrapping foods, chocolates,
photographic film, medicines, etc.

3. It is used in making different alloys.
4. Electric cables are made from aluminium.
5. It is used for making coins.
6. Powdered aluminium is mixed in oil to form paint.

Fact &Reason

Why is aluminum used in making body parts of airplane?
Aluminium is very light metal and is rusting free. Hence, aluminum is used to
make body parts of airplane.

Copper (a coinage metal)

Symbol : Cu
Atomic number : 29
Atomic weight : 63.5
Valency : 1, 2
Colour : Brownish red
Position in the periodic table : Period 4, Group IB, d-block
element.

Electronic configuration:

Shell KL MN
No. of electrons 2 8 18 1
1s2,2s22p6,3s23p6,4s1,3d10
Sub-shells

Occurrence

Copper is found in native as well as in combined state in nature. In
combined state, it occurs as ores in the following forms:

1. Copper pyrite or chalcopyrite CuFeS2

2. Copper glance or chalcocite Cu2S

3. Azurite [2Cu CO3. Cu(OH)2]

4. Malachite [Cu CO3. Cu(OH)2]

5. Cuprite Cu2O

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Fact &Reason

What is blister copper?
The 99% pure copper obtained by heating the powder of chalcopyrite with air in
big furnace is called blister copper. It is called blister copper due to the presence
of blisters in its surface caused by the bubbles of sulphur dioxide.

Properties

Physical properties
1. It is a hard and red brownish metal.
2. Its specific gravity is 8.25.
3. Its melting point is 10830C and boiling point is 23500C.
4. It is a good conductor of heat and electricity.
5. It has a good degree of malleability and ductility.

Uses
1. It is used to make household utensils such as cooking utensils,
boilers, water pots etc.
2. It is used for making electric wires and other appliances.
3. It is used to make coins. So, it is also known as coinage metal.
4. It is used for electroplating and electrotyping
5. Copper salts are used as insecticides and germicides.
6. It is used for making alloys such as brass, bronze, etc.

Silver (a coinage metal)

Symbol : Ag

Atomic number : 47

Atomic weight : 107.88 (=108)

Valency : 1

Position in the periodic table : Period; 5, Group 1B, d-block

(transition element).

Colour : Lustrous white

Electronic configuration

Shells K LMN O
No. of electrons 2 8 18 18 1
1s2,2s22p6,3s23p6,4s2,3d10,4p6,5s1,4d10
In sub-shells

Occurrence

It occurs in native as well as combined state. In combined form, silver
occurs as follows:

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1. Argentite or silver glance Ag2S
2. Silver copper glance (AgCu)2S
3. Horn silver AgCl
4. Ruby silver or pyrolite
3Ag2S.Sb2S3
Properties

Physical properties
1. It is a white shinning metal.
2. Its melting point is 960°C and boiling point is 1955°C.
3. It is a very good conductor of heat and electricity.
4. It is highly malleable and ductile.
5. Its specific gravity is 10.5.

Uses
1. It is used for making valuable utensils, coins and jewellery.
2. It is used for silver plating.
3. It is used in the manufacture of silver nitrate which is a very
useful laboratory reagent.
4. It is used for silvering mirrors and filling teeth.
5. Silver bromide (AgBr) is used in photography.
6. It is used industrially in electrical contacts and conductors.
7. It is used in the manufacture of solar pannel.
8. It is used in water purifiers to prevent growing of bacteria
and algae.

Gold (a coinage metal)

Symbol : Au

Atomic number : 79

Atomic weight : 197.2

Valency : 1, 3

Position in the periodic table : Period 6, Group IB, d-block

(transition element).

Colour : Lustrous yellow

Electronic configuration

Shells K L MNOP
No. of electrons 2 8 18 32 18 1
1s2,2s22p6,3s23p6,4s2,3d10,4p6,5s2,4d10,5p6,6s1,

4f14,5d10

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Occurrence

Gold is mostly found in native state because it is a noble metal which
does not react readily with other elements. It is usually found in
nature mixed with quartz rocks (reef gold) or in alluvial sand. In
combined state, it occurs as calverite (AuTe2).

Fact &Reason

Why is gold called noble metal?
Gold does not react with air, water, acids and other chemicals in normal condition.
So, gold is called noble metal.

Properties

Gold is the most malleable and ductile metal. So, it is also known as
the king of all metals.

Physical properties
1. It is a shinning yellow metal.
2. It is a good conductor of heat and electricity.
3. It is highly malleable and ductile.
4. It specific gravity is 19.3.
5. Its melting point is 1063°C and boiling point is 2530°C.

Uses
1. It is used for making jewellery, statues, etc,
2. It is used for making coins and medals.
3. It is used for filling teeth.
4. Compounds of gold are used in photography and medicines.
5. It is used for gold plating.
6. It is used to make gold leaf electroscope.

7. Its salts are used as anti - inflammatories in medicine.

Learn and Write

1. Aluminium is used to make body of aeroplanes. Why?
Aluminium is light metal. It does not get rusted. Therefore, it is

used for making the body of aeroplanes.
2. Gold is called the king of all metals. Why?
Gold is the most malleable and ductile metal. It does not get

rusted and remains in the native form even it gets exposed to
various chemicals. Therefore, gold is called the king of all metals.

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Main points to remember

1. Metals are the electropositive solid elements which are good
conductors of heat and electricity.

2. Non-metals are the electronegative elements which are bad
conductors of heat and electricity.

3. Metalloids are the elements whose properties are intermediate
between metals and non-metals.

4. Minerals are the naturally occurring substances which contain
metals.

5. The naturally occurring minerals from which metals can be
extracted profitably are called ores.

6. The branch of science which deals with the extraction of metals
from the ores and manufacture of metal products is called
metallurgy.

7. A brief summary of ores, physical constants and main uses of
metals is given below:

S.N Metal Chief ores/ Metal Physical Applications
minerals extracted constants (Main uses)
from (Physical
(chiefore) properties) Iron is used to
manufacture:
1. a. Haematite (Fe2O3) Colour : shiny a. steel
Iron (Fe) b. Magnetite (Fe3O4) grey b. rods, wires,
Z : 26 c. Siderite (FeCO3) State : Hard pipes, nuts and
A : 56 d. Limonite solid bolts, nails etc.
M.P: 1500°C c. instrument and
Valency: 2,3 (Fe2O3.3HO2) Haematite B.P : 2500°C weapons.
Period : 4 e. Iron pyrite (FeS2) Specific gravity d. household
Group: 8 f. copper pyrite : 7.86 utensils.
Conductivity: e. buildings, bridges,
(CuFeS2) (Fe2O3) Good vehicles etc.
Conductor

2. Aluminum a. Bauxite Bauxite Colour: Silvery Aluminium
(Al) (Al2O3.2H2O) (Al2O3.2H2O) white is used to
Z:13 b. Cryolite (Na3AlF6) State : Hard manufacture:
A: 27 c. Felspar (KAl solid a. paints.
Valency: 3 Si3O8) M.P: 660°C b. electrical
Period : 3 B.P : 1800°C wires, body of
Group :13 Specific gravity aeroplane, cars,
: 2.7 buses etc.
Conductivity : c. aluminium
Good conductor foils for wrapping
foods, medicines
etc.
d. coins.
e. electric cables,
alloys etc.

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3. Cupper (Cu) a. Copper pyrite Colour: Red Copper is used to
brownish manufacture :
Z : 29 or chalcopyrite Copper State : Hard a. electric wire
solid and other
A:63.57 (CuFeS2) pyrite or M.P: 1083°C appliances.
chalcopyrite B.P : 2350°C b. household
Valency: 1,2 b. copper glance or Specific gravity utensils such as
: 8.93 cooking utensils,
Period : 4 chalcocite (Cu2S) (CuFeS2) Conductivity : water pots etc.
Group : 11 c. Cuprite (Cu2O) Good conductor c. coins.
d.Malachite [CuCO3. d. alloys such as
Cu(OH)2] brass, bronze etc.

4. Silver (Ag) a. Argentite or silver Argentite or Colour :Shiny Silver is used to
Z:47 glance (Ag2S) silver glance white manufacture:
A:107.88 b. Horn silver (AgCl) (Ag2S) State : Hard a. jewellery,
Valency : 1 c. Silver copper solid coins and
Period : 5 glance [(AgCu)2S] M.P: 960°C valuable utensils.
Group : 11 d. Ruby silver or Specific gravity b. silver plate
pyrolite (Ag2Sb2S3) : 10.5 articles.
Conductivity : c. silver nitrate.
Good d. silver bromide,
Conductor which is used
in photography.
Silver is also
used for silvering
mirrors and
filling teeth.

5. Gold (Au) a. Alluvial sand Alluvial sand Colour: Gold is used in
Lustrous making:
Z:79 (Soil) yellow a. jewellery,
State: Hard statues etc.
A:197.2 b. Quartz rocks solid

Valency : 1,3

Period : 6

Group : 11

Exercise

A. Very short answer questions (1 mark)

1. What are ores? Give any two examples.

2. What is an alloy?

3. Write down the symbol, atomic number and atomic weight of

iron.

4. Write the name of any two metalloids.

5. Write a difference between metal and non-metal on the basis

of density.

6. Write the atomic number and atomic weight of copper.

7. What is blister copper?

8. Write two chief ores of iron with their molecular formulae.

9. In what group and period does gold lie in the modern

periodic table?

10. What are the atomic number and atomic weight of silver?

11. Write down the, electronic configuration of gold in the

modern periodic table.

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B. Short answer questions (2 marks)

1. Why is gold called noble metal?

2. Gold is found in pure state in nature but not iron, why?

3. Write two properties of aluminium that makes it suitable for

building body parts of the aeroplanes.

4. Copper is used to make electric wire, why ? Give two reasons.

5. Why are aluminium tools not affected by air and water?

C. Long answer questions (3 marks)

1. Write any three uses of aluminium.

2. Write any three uses of copper.

3. Write down any three uses of gold.

4. Write any three uses of iron.

5. Write down any three uses of silver.

6. Write the name and molecular formula of the major ores of

iron, copper, aluminium and silver.

Project Work

Study the uses of different metals at your home and write down

their physical properties and uses.

Glossary

• Crushed : ground, broken down into pieces

• Lump : a piece without any particular shape

• Extraction : taking out or separating a desired substance
from others (e.g. a metal from an ore)

• Alluvial : consisting of, or formed by sediment deposited
by flowing water

• Native form : element form, uncombined form

• Gold leaf electroscope : an instrument used for detecting and
measuring charge.

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Chapter Hydrocarbon

12 and
Its Compounds
Friedrich Kekulé
Friedrich August Kekulé was a
German organic chemist. He known
for proposing the structure of
benzeEnset.imated Periods: 5 (4T+1P)

Objectives

At the end of the lesson, students will be able to:
• define hydrocarbons;

• explain various types of hydrocarbons and their compounds.

The compounds which are formed by the chemical combination of
carbon and hydrogen are called hydrocarbons. The hydrocarbons are
called organic compounds. The branch of chemistry which deals with
hydrocarbons and their derivatives is called organic chemistry. The
organic compounds consist of covalent bonds between carbon and
hydrogen or carbon and carbon. Because of co-valency, a carbon atom
can form a chain with other carbon atoms. Hence, a number of carbon
atoms can combine with each other to form a chain of carbon atoms.
The property of carbon to form covalent bonds with its own atoms is
called catenation.

Naming of hydrocarbons

The organic compounds can be known by two kinds of names-common
or trivial name and scientific or IUPAC name. The name of a simple
hydrocarbon involves the use of word root and suffix. The word root
is based upon the number of carbon atoms in the molecule.

a) The word root according to number of carbon atoms is given
below:

No. of C-atoms Word root
Meth
C1 Eth
C2 Prop
C3 But
C4 Pent
C5

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C6 Hex
C7 Hept
C8 Oct
C9 Non
C10 Dec

b) The word root is followed by a primary suffix. The primary suffix
is based on the number of bonds between the carbon atoms.

Hydrocarbon Type of bond Suffix
Alkane Single (C–C) – ane
Alkene Double (C=C) – ene
Alkyne Triple (C≡C) – yne

For example

CH3 — CH2 – CH3

Word root: Prop (because there are 3 carbon atoms)

Primary suffix: ane (because there are single bonds)

Therefore, the name of the compound = Prop + ane = Propane.
c) If there is functional group in a compound, the name of the

compound consists of word root, primary suffix and secondary
suffix.

Types of hydrocarbons

The hydrocarbons can be divided into two types based on the kind of
bond present between the adjacent carbon atoms. They are: saturated
hydrocarbons and unsaturated hydrocarbons.
1. Saturated hydrocarbons
The hydrocarbon in which the adjacent carbon atoms are linked
by a single covalent bond is called saturated hydrocarbon. Such
hydrocarbons are also called alkanes. For example, methane (CH4),
ethane (C2H6), propane (C3H8), etc.
The general formula of saturated hydrocarbon is CnH2n+2 where 'n'
represents the number of carbon atoms. For example, if the saturated
hydrocarbon has 1 carbon atom, according to the formula Cn+H2n+2=
C1H2×1+2= CH4 (Methane). If 2 carbon atoms are present, then C2H2×2+2
= C2H6 (ethane and so on).

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Some more examples of alkanes with their molecular formula,
structural formula and IUPAC (International Union of Pure and
Applied Chemistry) name are given below:

S.N Name Molecular Condensed Structural formula
formula formula

H

1. Methane CH4 CH4 HC H
(C1) H

HH

2. Ethane C2H6 CH3CH3 HC C H
(C2) HH

HHH

3. Propane C3H8 CH3CH2CH3 HC C C H
(C3) HHH

4. Butane C4H10 CH3CH2 HHHH
(C4) CH2CH3 HC C C C H

HHHH

5. Pentane C5H12 CH3CH2CH2 HHHHH
(C5) CH2CH3 HC C C C C H

HHHHH

6. Hexane C6H14 CH3CH2CH2 H H H H HH
(C6) CH2CH2CH3 HC C C C CC H

H H H H HH

7. Heptane C7H16 CH3CH2CH2 H H H H HH H H
(C7) CH2CH2 HC C C C CC C
CH2CH3
H H H H HH H

8. Octane C8C18 CH3CH2CH2 H H H H HH H H
(C8) CH2CH2CH2 HC C C C CC C C H
CH2CH3
H H H H HH H H

9. Nonane C9C20 CH3CH2CH2 H H H H HH H H H
(C9) CH2CH2CH2 HC C C C CC C C C H
CH2CH2CH3
H H H H HH H H H

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CH3CH2CH2 H H H H HH H H H H

10. Decane C10H22 CH2CH2CH2 H C C C C C C C C C C H
(C10)
CH2CH2CH2 H H H H HH H H H H

CH3

The alkanes are also known as paraffins because they are chemically
less reactive.

2. Unsaturated hydrocarbons

The hydrocarbons in which the adjacent carbon atoms are linked

by multiple (double or triple) covalent bonds are called unsaturated

hydrocarbons. For example, ethene (C2H4), propene (C3H6), ethyne
(C2H2), etc. Unsaturated hydrocarbons are of two types.

a. Alkenes (olefins) b. Alkynes (acetylenes)

a. Alkenes

The hydrocarbons in which the two adjacent carbon atoms are linked
by double covalent bonds are called alkenes. The alkenes are also
known as olefins. The general formula of alkenes is CnH2n where 'n'
represents the number of carbon atoms.
The molecular formula, condensed formula, structural formula and
IUPAC names of some alkenes are given the below:

S.N Name Molecular Condensed Structural
formula formula formula

1. Ethene C2H4 CH2=CH2 HH
(Ethylene) C =C

HH

HH H

2. Propene C3H6 CH3CH=CH2 H C C= C
HH

CH3CH2 HH H
CH=CH2
3. Butene C4H8 H C C C= C

HHH H

HH H H H
CH3CH2CH2 H C C C C = C
4. Pentene C5H10 CH=CH2

HH H H

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b. Alkynes

The hydrocarbons in which two adjacent carbon atoms are connected
by triple covalent bonds are called alkynes. The general formula
of alkyne is CnH2n-2. The molecular formula, condensed formula,
structural formula and the IUPAC name of first four members of
alkynes are given below:

S.N Name Molecular Condensed Structural
formula formula formula

1. Ethyne C2H2 CH ≡ CH H – C ≡ C–H
(acetylene)
H

2. Propyne C3H4 CH3C ≡CH H C C ≡ C H
3. Butyne C4H6
4. Pentyne C5H8 H

CH3CH2 HH C≡C H
C ≡ CH HC C

HH

HH H
CH3CH2CH2 H C C C C ≡ C H

C ≡ CH
HH H

Fact &Reason

What is acetylene?

Acetylene is an unsaturated hydrocarbon in which two carbon atoms are bonded

with triple bond. It is also called ethyne.

Functional group

An atom or group of atoms bonded to a carbon atom which determines
the chemical properties of an organic compound is called functional
group. Some examples of functional groups are given in the table.

S.N Name of functional Symbol Structure Class of organic
group compounds
– OH –O–H alcohol
1. Hydroxyl –O– –O– ether

2. Ethereal O aldehyde
CH
3. Aldehyde – CHO

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O ketone

4. Keto – CO –

C

5. Carboxyl – COOH O Carboxylic acid

C OH

Alkyl group

A group of atoms (radical) derived from alkanes by removing one
hydrogen atom is called alkyl group or alkyl radical. It is represented
by R in short form.

Alkane −H → Alkyl group.

Examples: Methane: CH4 – H = CH3 (Methyl group)
Ethane: C2H6 – H = C2H5 (ethyl group) and so on.

Homologous series

A series of organic compounds having same functional group and
two successive members differing by a CH2 unit is called homologous
series. Each member of a homologous series is called homologue.
All the members of a homologous series can be represented by the
same general formula. For example, the general formula of alcohol is
CnH2n+1OH homologous series of alcohol is:

CH3– OH Methanol

CH3–CH2–OH Ethanol

CH3–CH2–CH2–OH Propanol

CH3–CH2–CH2–CH2–OH Butanol

CH3–CH2–CH2–CH2–CH2–OH Pentanol

Characteristics of homologous series
1. All the members of a homologous series have same functional group.
2. They can be represented by the same general formula.
3. Two adjacent members of a homologous series differ by a –CH2 unit.
4. They have similar chemical properties.
5. They can be prepared by same general methods of preparation.

Some important hydrocarbons

Methane, ethane, propane and butane are some important
hydrocarbons.

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Methane (CH4)

It is the simplest hydrocarbon and occurs as a colourless gas. It is
found in the gaseous state at room temperature. It is also called marsh
gas because it is formed by the decomposition of organic matter in
marshy areas. Methane is also found in natural gas, petroleum and
coal mines, bio-gas etc.

H

HC H

CH4 H

Condensed formula Structural formula

Uses of methane
1. It is used to make printing ink and paints.
3. It is used as a cooking fuel in the form of LPG (Liquefied
Petroleum Gas).
2. It is used to make carbon black which is needed in rubber
industries.
4. It is used in the manufacture of hydrogen.
5. It is used in manufacture of methyl alcohol (CH3OH), chloroform
(CHCl3), formaldehyde (HCHO), carbon tetrachloride (CCl4), etc.

Fact &Reason

Which gas is called marsh gas and why?

Methane is called marsh gas as it is found in marshy places.

Ethane (C2H6)
It is the second member of homologous series of alkanes which occurs
in natural gas and petroleum mines. It is a colourless gas.

HH

HC C H

CH3–CH3 H H
Condensed formula Structural formula of ethane

Uses

1. It is used as a cooking fuel.
2. It is used to make different types of compounds.

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Propane (C3H8)

It is the third member of homologous series of alkanes. It is found in
petroleum mines. It is a colourless gas.

HHH

HC C C H

CH3–CH2–CH3 H H H

Condensed formula Structural formula of propane

Uses

1. It is used as a fuel in closed bottles such as gas lighter.

Butane (C4H10)

It is a colourless gas which can be liquefied at room temperature
under high pressure. It is also found in petroleum mine. It has two
isomers: n - butane and iso-butane.

CH3 – CH2 – CH2 – CH3

Butane

The organic compounds having same molecular formula but different
structural formula are called isomers. The property of the organic
compounds to have isomers is called isomerism. The isomers have
different physical and chemical properties.

HHH

HHHH HC C C H
HC C C C H
HH
HHHH HC H

H

n- butane Iso-butane

Uses

Butane and iso-butane are the main constituents of liquefied
petroleum gas.

Alcohol

Alcohols are the organic compounds which contain hydroxyl (– OH)
group as the functional group. They are the derivatives of alkanes

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which are formed by replacing hydrogen atoms of alkane by hydroxyl
(OH) group.

For example:

CH4 –H CH3 – OH
+ OH

Methane Methyl alcohol

–H

CH3CH3 + OH CH3CH2OH

Ethane Ethyl alcohol

Naming of alcohol

The IUPAC name of a simple alcohol involves three parts- word root,
primary suffix and secondary suffix.

For example: CH3CH2OH
Common name: Ethyl alcohol

For IUPAC name:

Word root = Eth (as there are 2 C atoms)

Primary suffix = ane (as there is single bond between C atoms)

Secondary suffix = ol ('ol' represents alcohol)

Hence, IUPAC name CH3CH2OH = Eth + ane + ol

= Ethanol

Activity12 .1 Write down the IUPAC name of:

a. CH3OH b. CH3CH2CH2OH c. CH3CH2CH2CH2OH

Types of alcohols

Depending upon the number of hydroxyl groups in a molecule, there
are three types of alcohol.

a. Monohydric alcohol

The alcohol which contains only one hydroxyl group (-OH) in a molecule
is called monohydric alcohol. It is formed by the replacement of one
hydrogen atom of an alkane by one hydroxyl group.

For example,

–H CH3 – OH

CH4 + OH

Methane Methyl alcohol

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The other examples are:

CH3 – CH2 – OH CH3–CH2–CH2–OH CH3–CH2–CH2–CH2–OH

Ethyl alcohol Propyl alcohol Butyl alcohol

b. Dihydric alcohol

The alcohol which contains two hydroxyl groups (-OH) in a molecule
is called dihydric alcohol. It is formed by the replacement of two
hydrogen atoms each from one carbon of ethane by two hydroxyl
groups.

HH HH

HC C H –2 H HC C H
+2 OH
HH
OH OH

Ethane Ethylene glycol

c. Trihydric alcohol

The alcohol which contains three hydroxyl groups in a molecule is
called trihydric alcohol. Glycerol, a trihydric alcohol is formed when
three hydrogen atoms of propane are replaced by three OH groups.
For example,

HHH HH H

H C C C H –3 H HC C C H
+3 OH

HHH OH OH OH

Propane Glycerol (glycerine)

Some commercially important alcohols

Methyl alcohol (CH3OH)

It is a monohydric alcohol which contains a single carbon atom in a
molecule. Its IUPAC name is methanol. It is a colourless and highly
poisonous liquid. Drinking methyl alcohol causes blindness.

H

CH3OH H C OH
H
Methanol (condensed formula) Methanol (Structural formula)

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Uses

1. It is used as fuel because it produces large amount of heat
without smoke. Hence, it is used in sprit lamp.

2. It is used for the preparation of methylated spirit.
3. It is used to manufacture perfume.
4. It is used as a solvent for paints, varnishes, oils etc.
5. It is used to make methyl chloride, formaldehyde etc, which

is an important fuel.

Fact &Reason

Which alcohol is used to manufacture formaldehyde?
Methyl alcohol is used to manufacture formaldehyde.

Ethyl alcohol (C2H5OH)

It is a colourless liquid with distinct alcoholic smell and intoxicating
effect. It has a burning taste. Its IUPAC name is ethanol. It is easily
soluble in water. In general, the term 'alcohol' is understood as ethyl
alcohol.

HH

H C C OH

H H

Ethyl alcohol (ethanol)

Uses

1. It is used in alcoholic beverages for drinking purpose because
of its intoxicating effect.

2. It is used to make medicines, soaps, synthetic rubber etc,
3. It is used as solvent for fat, oil, paints, etc.
4. It is used in thermometer as a thermometric liquid.
5. It is used as fuel.

Glycerol or Glycerine [C3H5 (OH) 3]

Glycerol is a colourless thick liquid with sweet taste. It is soluble in
water but insoluble in ether. Glycerol is a trihydric alcohol which is
formed by replacing three H atoms (one from each carbon atom) of
propane by three OH groups. It is produced by the hydrolysis of fat
or oil in the presence of alkali.

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H HH CH2OH

HC C C H or, CHOH

OH OH OH CH2OH

Glycerol
Uses

1. It is used in the manufacture of soaps and cosmetics.
2. It is used as a sweetening agent in confectionery, beverages

and medicines.
3. It is used in the manufacture of printing inks and stamp pad

inks.
4. It is used for preservation of fruits and tobacco.
5. It is used as a lubricant.
6. It is used as medicine to protect skin from being dried.

Glucose

Glucose is a white crystalline powder with sweet taste. It is also
known as dextrose and is an instant source of energy. Its molecular
formula is C6H12O6. It is readily soluble in water. It is one of the
monosaccharide forms of carbohydrates. The other monosaccharides
are fructose and glactose. Glucose is directly absorbed into the blood
through small intestine. It is used by the cells of our body to produce
ATP (Adenosine Triphosphate). Our body utilizes ATP for energy.

H H OH H H

CH2OH C C C C C

OH OH H OH O

Structure of glucose

Glucose is found in honey and fruits. It is also produced in our
intestines due to the digestion of carbohydrates. Glucose is the main
source of energy for our body. It has an important role in metabolic
activities in the body. Glucose is essential as well as harmful for the
organisms.

High level of glucose in the blood can result in the swelling of the
body. Similarly, the low blood glucose level is also harmful to our
body.

Learn and Write

1. Propane is a saturated hydrocarbon. Why?

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A molecule of propane contains three carbon atoms. All carbon
atoms are linked by a single bond. Therefore, propane is a
saturated hydrocarbon.

2. Alkanes are also called paraffins. Why?

Alkanes are chemically less reactive. Therefore, they are called
paraffins.

3. Methane is called marsh gas. Why?

Methane is formed naturally by the decomposition of organic
matter under water in marshy area. Therefore, it is found in
marshy area and is called marsh gas.

4. Glycerol is trihydric alcohol. Why?

Glycerol is formed by the displacement of 3 hydrogen atoms of
propane by 3OH radicals one from each carbon atom. Due to
the presence of 3OH radicals, glycerol is called trihydric alcohol.

H HH H HH

–3H HC C C H

H C C C H +3OH– OH OH OH
H HH
Glycerol
Propane

Main points to remember

1. The compounds which are formed by the chemical combination
of carbon and hydrogen are called hydrocarbons.

2. The hydrocarbons and their derivatives are called organic compounds.
3. The branch of chemistry which deals with the hydrocarbons

and their derivatives is called organic chemistry.
4. The hydrocarbons in which the adjacent carbon atoms are linked

by a single covalent bond are called saturated hydrocarbons.
5. The hydrocarbons in which the adjacent carbon atoms are

linked by multiple (double or triple) covalent bonds are called
unsaturated hydrocarbons.
6. An atom or a group of atoms bonded to a carbon atom which
determines the chemical properties of an organic compound is
called functional group.
7. A group of atoms or a radical derived from alkanes by removing
one hydrogen atom is called alkyl group or alkyl radical.
8. A series of organic compounds having same functional group
and two successive members differing by a - CH2 unit is called
homologous series.

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9. The organic compounds having same molecular formula but
different structural formula are called isomers.

10. A group of organic compounds which contain hydroxyl group (–OH)
as the functional group is called alcohol.

11. Glucose is a white crystalline powder with sweet taste. It is also
known as dextrose and is an instant source of energy.

Exercise

A. Very short answer questions ( 1 mark )

1. What is homologous series?

2. Write general formula of alkene.

3. What is acetylene?

4. Define saturated hydrocarbon with two examples.

5. Define unsaturated hydrocarbon with two examples.

6. What is IUPAC name of methyl alcohol?

7. What is the IUPAC name of ethyl alcohol?

8. Write down the molecular formula of methane gas with its

one property.

9. Define isomers and isomerism.

10. Name the hydrocarbon which is used to make chloroform.

11. What is propane? Where is it found?

12. Write down the functions of glucose in animal body.

13. Write any two examples of saturated hydrocarbons.

14. Define monohydric alcohol with an example.

15. Define dihydric alcohol with an example.

16. Define trihydric alcohol with one example.

17. Draw a structural formula of acetylene and mention one use

of it.

18. Which alcohol is used to manufacture formaldehyde?

B. Short answer questions ( 2 marks)

1. Write the name and structural and condensed formula of a

saturated hydrocarbon which has three carbon atoms.

2. Differentiate between saturated hydrocarbons and

unsaturated hydrocarbons.

3. What type of hydrocarbons are called paraffins, why?

4. Write structural formula and one use of trihydric alcohol.

5. Write the molecular formula of glycerol and write its uses.

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C. Long answer questions (3 marks)

1. Write the structural formula of glycerol. Why is glycerol

called trihydric alcohol?Mention its uses.

2. Write down any three uses of methyl alcohol.

3. Write down any three uses of ethyl alcohol.

4. Write down general formula of alkyne. Write the name

of member of alkynes which contains equal number of

hydrogen and carbon. If such compound reacts with sufficient

hydrogen, what will be the result?

5. Write down any three uses of butane.

6. Write down three uses of ethane.

7. Write down three uses of methane.

8. Write the structural formula of ethane and answer the

following questions.

i) Write the general formula of the above compound

ii) Write the name of the compound formed by the removal

of one hydrogen by one OH from the above compound.

D. Very long answer questions (4 marks)

1. Write the structural formula of glycerol and answer the

following questions:

i) Write the IUPAC name of it. In which group of organic

compound is it kept?

ii) Which type of hydrocarbon is formed if three 'OH' are

replaced by three 'H' atom?

iii) Give two reasons to use this compound in fruits and

food materials.

2. Write the structural formula of propane and answer the

following questions.

i) Give the molecular formula of this compound.

ii) Write its general formula.

iii) Write the name and structural formula of the compound

formed if one 'H' atom from each carbon is replaced by

one 'OH' in each carbon?

iv) Write a use of the compound thus formed.

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3. Write down the name and three uses of the compound whose
structural formula is given below:

H H OH H H

CH2OH C C C C C
OH OH H OH O

4. Which compound is represented by general formula
CnH2n+1OH ? If value of n is 2 in this formula, which
compound is formed? Write its structural formula. If OH of
this compound is replaced by H, which compound is formed?
Write its name and molecular formula.

Project Work

Consult books in a library and prepare the homologous series (Writing at
least ten members) of the following compounds:

a. Alkanes b. Alkenes c. Alkynes d. Alcohol
e. Ether f. Aldehydes g. Ketones h.Carboxylic acids

Glossary

• Suffix : one or more letters added at the end of word.
• Prefix
: one or more letters added at the beginning of a
• Marsh gas word.

: Methane

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Chapter Materials Used
in daily Life
13 Joseph Aspdin

Joseph Aspdin was an English
cement manufacturer who obtained
the patent for Portland cement on 21

OctoEbesrti1m8a2t4ed Periods: 10 (8T+2P)

Objectives

At the end of the lesson, students will be able to:

• explain the composition and uses of cement, glass, fibre, ceramics,

plastics, soap, detergent and insecticides;

• explain the types and uses of nitrogen, phosphorus and potassium

fertilizers;

• explain importance of compost manure in agriculture;

• explain chemical pollution, their effects and control measures.

Applied chemistry is the branch of chemistry which applies physical
and chemical processes for the transformation of raw materials into
the useful products. The industries include cement industry, glass
industry, fertilizer production industry, plastics industry, pulp and
paper industry, soap and detergent industry, etc. The industrial
chemistry enables human beings to experience the benefits of
chemistry when we apply it in the production of useful products. When
we apply chemistry in the transformation of materials and energy
to make usable products, this results in growth of food production,
improvement in health and hygiene, shelter and clothing.
In this chapter, we shall discuss about some industrial products such
as cement, glass, ceramics, plastics, fibres, fertilizers, etc.

Cement

Cement is a mixture of calcium silicate and calcium aluminate in the
form of fine grey powder, which binds sand, gravel and bricks when
treated with water and dried for some time.

Manufacture of cement

Cement is manufactured by heating a mixture of limestone and a special
type of clay which consists of oxides of aluminium and silicon (Al2O3.
SiO2) in the ratio of 2:1 by mass at the temperature of about 16000C.

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1. Raw materials required

Limestone (CaCO3): Two-thirds of total mass
Clay containing alumina and silica (Al2O3.SiO2): One-third of

total mass

Gypsum (CaSO4.2H2O ): About 2-3% of total mass.
2. Steps involved

The process of manufacture of cement involves three principal
steps:

a. Crushing and grinding
b. Strong heating (burning)
c. Final grinding (powdering)

Crushing and grinding

The raw materials, i.e., limestone and clay are crushed separately.
Then two-third part of crushed limestone and one third part of clay
containing alumina and silica are mixed and ground into fine power.
The powdered material is mixed with water during grinding to make
a soapy mixture called slurry.

Strong heating History of Cement Production
The slurry is then

passed through tall England: 1825
rotatory kiln, which Germany: 1855
has a temperature Belgium: 1855
of about 1400°C to USA: 1872
1600°C. A kiln is a India: 1904
cylindrical furnace Nepal: 1976 (Hetauda Cement Factory)
which is made of

steel and lined with

fire bricks. The slurry materials undergo chemical change while

passing downwards from the top of the kiln due to high temperature

of the kiln.

At the high temperature, limestone decomposes into calcium oxide
and carbon dioxide. Calcium oxide combines with alumina (Al2O3)
and silica (SiO2) to form calcium aluminate and calcium silicate
respectively.

CaCO3 + Al2O3 + SiO2 ∆ → CaSiO3 + CaAl2O3 + CO2

Alumina Slica Calcium silicate Calcium aluminate

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The mixture of calcium aluminate and calcium silicate takes the
form of small balls called cement clinker. The cement clinker is the
mixture of calcium aluminate and calcium silicate in the form of
small reddish balls.

Final grinding

The cement clinker is cooled and mixed with 2-3% of gypsum
(CaSO4.2H2O). The mixture is then crushed into fine powder. Thus
produced fine powder is called cement. Gypsum increases the setting
time of the cement. It increases the quality of cement.

3. Handling and storage of cement

We should not store cement in damp or moist place because it easily
absorbs water and gets hardened itself inside the sack. Thus, it
becomes useless. The cement should also be protected from rainwater
during transportation.
Cement products
Mortar: The mixture made by blending fine sand and water with
cement is called mortar. It is used to construct and plaster the walls.
Concrete: The uniform mixture of sand, gravel, cement and water
is known as concrete. It is used in flooring and roofing of buildings.
Reinforced cement concrete (RCC): The concrete having an iron
framework inside it is called reinforced cement concrete.

Uses of cement
a. Mortar is used to construct walls of buildings because it holds the
bricks, stones, etc together. It is also used for plastering the walls.
b. Cement is used for the construction of buildings, roads, bridges, dams etc.
c. Concrete is used for flooring and roofing of buildings. It is also used
for making pillars.
d. Reinforced cement concrete is used for making roofs and pillars.

Cement factories of Nepal
There are several cement factories in Nepal such as Hetauda cement
factory (Makwanpur), Udaypur cement factory (Udaypur), Triveni
cement factory (Bharatpur), etc.

Fact &Reason

Why is gypsum added to cement?
Gypsum is added to cement to increase the setting time of cement.

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Glass

An amorphous, hard, transparent and homogeneous mixture of
silicates of different metals is called glass. It is considered as super
cooled liquid. Chemically it is the silicate of metals. The main raw
material required for the production of glass is silica (Silicon dioxide,
SiO2 ). Sand is the main source of silica. It is also found in quartz.
Silica and compounds of certain metals react to form silicates.

Characteristics of glass
1. Glass is a hard, transparent, amorphous and homogeneous
mixture of metallic silicates.
2. It does not have fixed composition and particular formula.
3. It does not have fixed melting point.
4. Glass is a super cooled liquid because molecules of glass flow
very slowly like the molecules of liquid.

Therefore, window panes of old house are thicker at the lower parts.

Types of glass

The properties of glass depend upon the proportion of components
added to silica during their production. Some important types of
glass are given below:

1. Quartz glass

It is a pure crystalline glass. It is prepared by heating silica to
about 1600°C and then cooling the product.

Pure silica (SiO2) 1600°C → Quartz glass

Characteristics

a. It is very hard.

b. It is not affected by water and acids.

c. It remains unaffected even at high temperature. Even red

hot quartz glass when placed in cold water does not crack.

Uses

a. It is used in making electrical devices.

b. It is also used in making coloured quartz (gems).

c. It is used for making different types of laboratory appliances

such as crucible, basin, etc.

2. Water glass
The glass made of sodium silicate or potassium silicate is called
water glass. It is produced by heating silica with sodium carbonate
or potassium carbonate at about 800°C. Since this glass is soluble in

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water, it is known as water glass.

SiO2 + Na2CO3 800°C → Na2SiO3 + CO2
Sodium silicate CO2

SiO2 + K2CO3 800°C → K2SiO3 +

Potassium silicate

Characteristics

It is not affected by fire but is soluble in water.

Uses
a. It is used for making fireproof materials.
b. Solution of water glass is used for making gums, pastes and
adhesives.
c. It is used for making silica garden.

3. Ordinary glass (Soft glass or soda lime glass)

The fused homogeneous mixture of sodium silicate and calcium
silicate is called ordinary glass. It is obtained by heating the mixture
of 50% silica, 25% pieces of glass, 15% sodium carbonate and 10%
calcium carbonate at about 1500°C.

2SiO2 + Na2CO3 + CaCO3 + glass pieces 1500°C → Na2SiO3.CaSiO3 + 2CO2

(50%) (15%) (10%) (25%) (Sodium silicate and calcium silicate)

Ordinary glass

During the manufacture of ordinary glass, limestone is added to make
glass insoluble in water. The broken glass pieces help in melting of
the mixture. Then the glass articles are made using the molten mass.
The articles are then cooled slowly. The process of slow cooling of
prepared glass articles is called annealing.

If lead monoxide is added during manufacture of ordinary glass, it
reacts with silica to form lead silicate glass. Lead monoxide increases
the refractive index of glass and decreases the transparency. So, it is
used for making prism, lens, glass slab, etc.

Characteristics

It is insoluble in water. Ordinary glass melts at low temperature and
hence it is called soft glass.

Uses

It is used in the manufacture of simple bottles, light bulbs,
windowpanes, glass sheets, glass tubes, etc.

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4. Hard glass (Potash lime glass)

The glass prepared from the fused homogeneous mixture of potassium
silicate and calcium silicate is called hard glass. The hard glass is
prepared by heating the mixture of silica, potassium carbonate and
calcium carbonate at high temperature. The hard glass is also called
potash lime glass.

2SiO2 + K2CO3 + CaCO3 ∆ → K2SiO3.CaSiO3 + 2CO2

Potassium silicate and calcium silicate

Characteristics
a. It melts at very high temperature.
b. It is hard and strong glass.

Uses

It is used for making laboratory apparatus like beakers, hard glass
test tube, electric bulb, tube light, etc.

Fact &Reason

Why is potash lime glass called hard glass?

Potash lime glass is called hard glass because it has high melting point and can

withstand higher temperature. It is also more resistant to the acids.

Differences between soft glass and hard glass

Soft glass Hard glass

1. It is the mixture of sodium 1. It is the mixture of potassium

silicate and calcium silicate. silicate and calcium silicate.

2. It melts at low temperature. 2. It melts at high temperature.

3. It is prepared by heating the 3. It is prepared by heating the

mixture of silica, calcium mixture of silica, calcium

carbonate, sodium carbonate carbonate and potassium

and pieces of glass. carbonate.

5. Borosilicate glass (Pyrex glass)

The homogeneous mixture of sodium silicate, calcium silicate and
boron silicate is called borosilicate glass. It is also known as pyrex
glass. The borosilicate glass is produced by heating the mixture of
sodium carbonate, calcium carbonate, silica and boric oxide at high
temperature.

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