SCIENCE FOR 5 PART 2

2HEME

Exploration of
Elements in Nature

Malaysia is the largest producer and exporter of latex gloves
in the world. Natural rubber is an organic carbon compound.
Is synthetic rubber also an organic carbon compound?

Video Lithium Fluorine

http://buku- 113
teks.com/sc5113

Lithium is used to
build electrochemical cells namely
cells, which are
electrolytic cell and
chemical cell. Name one
electrolytic battery from another
type of ion which can potentially
replace lithium-ion battery. Is the
rate of chemical reaction in
electrochemical cells high or low?

4CHAPTER RATE OF
REACTION

Define rate of reaction.

State five factors that affect rate of reaction.

Give three examples of applications of the
concept of rate of reaction in daily life
and industries.

Let’s study

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114

Science Bulletin

The process of making toast involves a chemical reaction known
as the Maillard reaction. In the Maillard reaction, carbohydrate
reacts with protein to form Amadori compounds that cause bread
to become brown and turn into toast. The Maillard reaction is a
fast reaction.

Keywords

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115

4.1 Introduction to Rate of Reaction

Fast Reactions and Slow Reactions in Daily Life

A chemical reaction is a process in which one or more reactants are converted to
one or more products.

Reactant Chemical reaction Product

For example, the reaction between the reactants, colourless potassium iodide
solution and colourless lead(II) nitrate solution will produce yellow-coloured
lead(II) iodide precipitate and colourless potassium nitrate solution as the products.

Lead(II) nitrate + Potassium iodide Lead(II) iodide + Potassium nitrate

Reactants Products

During a reaction, reactant changes into product. As such, the quantity of
the reactant decreases while the quantity of the product increases in that reaction
(Figure 4.1).

Quantity of reactant Quantity of product

Quantity of reactant Quantity of product
decreases with time increases with time

Time Time

Figure 4.1 Graphs of changes in quantities of reactant and product
against time

Observe and understand the similarities and differences between the graphs of
changes in the quantity of reactant or product against time in fast reactions and
slow reactions (Figures 4.2(a), (b) and 4.3).

Quantity of Quantity of
reactant product

Fast reaction: Slow reaction: Fast reaction: Slow reaction:
Quantity of Quantity of reactant Quantity of Quantity of product
reactant decreases slowly. product increases slowly.
decreases increases quickly.
quickly.

0 Time 0 Time

(a) Quantity of reactant against time (b) Quantity of product against time

Figure 4.2 Graphs of changes in quantities of reactant and product against time
116 4.1.1

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Figure 4.3 Similarities and differences between fast reaction and slow reaction

Photographs 4.1 and 4.2 show
examples of reaction in daily life.
Which photograph represents
a fast reaction and a slow reaction?
Explain your answer.

Photograph 4.1 Photograph 4.2
Burning of butane gas Rusting of iron

Activity 4.1

To identify examples of fast reactions and slow reactions 21st Century Skills
Instructions
• TPS
• Discussion

1. Carry out this activity in groups.
2. Gather information on several examples of reactions usually found in daily life from

the Internet, print media and other electronic media.
3. Identify and discuss whether the examples of reactions that you have collected are fast

reactions or slow reactions.
4. Present the outcome of your group discussion in the form of a multimedia presentation.

4.1.1 117

Rate of Reaction

Rate of reaction is the change in the quantity of reactant or product per unit time.

Rate of reaction = Change in the quantity of reactant or product

Time taken for the change to occur

Among the changes in quantity of reactant or product Entrepreneurship
that can be observed or measured in a specific period of

time to determine the rate of reaction include: Why is the price of cheese

• decrease in the mass, volume or concentration normally high? How can the
of the reactant price of cheese be reduced?

• increase in the mass, volume or concentration

of the product

• decrease or increase in the pressure, temperature, pH value, electrical conductivity,

heat conductivity or intensity of colour of the reacting mixture

• increase in the volume or pressure of the gas released

• increase in the height of the precipitate formed

Determining the Rate of Reaction

Example

0.3 g of magnesium tape reacts completely with excess dilute hydrochloric acid in
30 s (Figure 4.4). Calculate the rate of reaction of this reaction.

0 s 10 s 20 s 30 s

Magnesium
tape

Figure 4.4 Quantity of magnesium tape, a reactant,
decreases with time

Solution

Rate of reaction = Decrease in mass of magnesium

Time taken

= (0.3 – 0.0) g
30 s

= 0.3 g
30 s

= 0.01 g s–1

118 4.1.2 4.1.3

Chapter 4 Rate of Reaction

The rate of reaction of a reaction can be measured as:
1. Average rate of reaction
The average value for the rate of reaction that occurs in a specific time interval.

Example

Volume of hydrogen gas (cm3) Observe Figure 4.5.
Calculate the average rate of reaction:
35.0 (a) for the first minute
30.0 (b) for the first 2 minutes
25.0 (c) in the second minute
20.0 (d) in the third minute
15.0 (e) for the whole reaction
10.0
5.0 Average rate of First minute is
reaction for the from 0 s to
0 Time (s) first minute 60 s
60 120 180 240 300 360
Figure 4.5 Total volume of hydrogen gas

Solution collected in the first
(a) Volume of hydrogen gas (cm3)
= 60 seconds
35.0 Time of reaction
30.0
25.0 = 20.00 cm3
20.0 60 s
15.0
10.0 = 0.33 cm3 s–1
5.0
Average rate of First 2 minutes
0 Time (s) reaction for the is from 0 s to
60 120 180 240 300 360 first 2 minutes 120 s

(b) Volume of hydrogen gas (cm3) Total volume of hydrogen gas

35.0 collected in the first
30.0
25.0 120 seconds
20.0 = Time of reaction
15.0
10.0 = 30.00 cm3
5.0 120 s

0 Time (s) = 0.25 cm3 s–1
60 120 180 240 300 360

4.1.3 119

(c) Volume of hydrogen gas (cm3) Average rate of Second minute
reaction in the is from 60 s to
35.0 second minute 120 s
30.0
25.0 Total volume of
20.0 hydrogen gas collected
15.0
10.0 from 60 s to 120 s
= Time of reaction
5.0
0 Time (s) = (30.00 – 20.00) cm3
60 120 180 240 300 360 (120 – 60) s

(d) Volume of hydrogen gas (cm3) = 10.00 cm3
60 s
35.0
30.0 = 0.17 cm3 s–1
25.0
20.0 Average rate of Third minute is
15.0 reaction in the from 120 s to
10.0 third minute 180 s

5.0 Total volume of
0 Time (s)
60 120 180 240 300 360 hydrogen gas collected

(e) Volume of hydrogen gas (cm3) from 120 s to 180 s
= Time of reaction
35.0
30.0 = (35.00 – 30.00) cm3
25.0 (180 – 120) s
20.0
15.0 = 5.00 cm3
10.0 60 s
5.0
= 0.08 cm3 s–1
0 Time (s)
60 120 180 240 300 360 Average rate of reaction for the
whole reaction
120
Total volume of

hydrogen gas collected
= Time taken for the reaction

to complete

= 35.00 cm3 Reaction ends at
180 s 180 s and not
360 s
= 0.19 cm3 s–1

4.1.3

Chapter 4 Rate of Reaction

2. Rate of reaction at a particular point of time or instantaneous rate of reaction
The rate of reaction at any particular point of time or specific instance.

ExEamxapmlep1le

Rate of Gradient of the Volume of hydrogen gas (cm3)

reaction at = tangent to the

time t curve at time t

Observe Figure 4.6. 50.0 P

Rate of Gradient of the

reaction tangent to the 40.0
at the = curve at the

20th second 20th second

= PQ
RQ
30.0
= (49.0 – 21.0) cm3 20.0 R
(29 – 9) s
28.0 cm3
= 20 s Q

= 1.40 cm3 s–1

10.0

Science 0 40 Time (s)
10 20 30
How to draw a tangent Figure 4.6
http://buku-teks.com/
sc5121

Example 2

In an experiment, excess zinc granules reacted with dilute hydrochloric acid
(Figure 4.7).

Hydrogen gas

Delivery tube Burette
Conical flask
Dilute hydrochloric acid Water Retort stand
Zinc granules
Basin 121
4.1.3 Figure 4.7

The volume of hydrogen gas released is recorded at intervals of 40 seconds. The graph
of volume of hydrogen gas against time is shown in Figure 4.8.

Volume of hydrogen gas (cm3)

50.0
40.0
30.0
20.0
10.0

0 40 80 120 160 200 240 Time (s)
Figure 4.8

For this reaction,
(a) calculate the rate of reaction at the 60th second
(b) calculate the rate of reaction at the 120th second

Solution
(a)

Volume of hydrogen gas (cm3)

50.0 Y
43.0 Z
40.0

30.0
23.0 X
20.0

10.0

0 20 40 60 80 100 120 160 200 240 Time (s)

122 4.1.3

Chapter 4 Rate of Reaction

Rate of reaction at the 60th second
= Gradient of tangent of curve at the 60th second

= YZ Rate of reaction at time t = Gradient of tangent of curve at time t
XZ
YZ
(43.00 – 23.00) cm3 = XZ
(100 – 20) s
=

= 20.00 cm3
80 s

= 0.25 cm3 s–1

(b) Volume of hydrogen gas (cm3)

50.0 Q
47.5

40.0 P
38.5 R

30.0

20.0

10.0

0 40 80 120 160 200 240 Time (s)

Rate of reaction at the 120th second
= Gradient of tangent of curve at the 120th second

= QR Rate of reaction at time t = Gradient of tangent of curve at time t
PR
= QR
(47.50 – 38.50) cm3 PR
(160 – 80) s
=

= 9.00 cm3
80 s

= 0.11 cm3 s–1

4.1.3 123

Activity 4.2

To solve numerical problems involving data analysis 21st Century Skills

Instructions • TPS
• Discussion
1. Carry out this activity individually.
Table 4.1
2. Solve the following numerical problems involving data analysis:
Volume of oxygen
(a) 1.3 g of zinc powder is mixed with excess gas (cm3)
0.00
dilute nitric acid. 480 cm3 of hydrogen gas is 14.50
23.00
collected in 10 s. Calculate the average rate 28.50
33.00
of reaction for the whole reaction in cm3 s–1. Time (s) 36.50
(b) The volume of oxygen gas released from 39.00
40.00
a mixture of hydrogen peroxide solution 0 40.00
and manganese(IV) oxide powder is 30 40.00
recorded at intervals of 30 seconds for

270 seconds in Table 4.1. 60
(i) Based on Table 4.1, draw a graph of 90
120
volume of oxygen gas against time.
(ii) Calculate the average rate of reaction:

• for the first 2 minutes 150
• in the second minute 180
• for the whole reaction 210
(iii) Calculate the rate of reaction:

• at the 60th second 240
• at the 150th second 270
• at the 240th second

Formative Practice 4.1

1. Give one example of a fast Volume of hydrogen gas (cm3)
reaction and one example of
a slow reaction in daily life. 70.0
60.0
2. Define rate of reaction. 50.0
40.0
3. Figure 1 shows the graph 30.0
of volume of hydrogen gas 20.0
released against time. 10.0

Calculate the average rate of
reaction:
(a) for the first 2 minutes
(b) in the second minute
(c) for the whole reaction

0
30 60 90 120 150 180 210 240 Time (s)
Figure 1

124 4.1.3

4.2 Chapter 4 Rate of Reaction

Factors Affecting Rate of Reaction

There are five factors affecting the rate of reaction (Figure 4.9).
Factors affecting rate of reaction

Temperature of reactants Concentration of reactants Size of solid reactants

Presence of catalyst Pressure (reactions involving
reactants in gaseous form)

Figure 4.9 Factors affecting the rate of reaction

1. When the temperature of reactants increases, the rate of reaction increases.
2. When catalyst is used in a reaction, the rate of reaction increases.
3. When the concentration of reactants increases, the rate of reaction increases.
4. When pressure increases, the rate of reaction involving gaseous reactants increases.
5. When the size of solid reactants decreases, the rate of reaction increases.

Let us carry out Experiments 4.1 – 4.4 to study how factors such as the
temperature of reactants, concentration of reactants, size of reactants and presence of
catalyst affect the rate of reaction.

Experiment 4.1

Aim: To study the effect of temperature of reactants on rate of reaction

Problem statement: How does temperature of reactants affect the rate of reaction?

Hypothesis: The higher the temperature of reactants, the higher the rate of reaction.

Variables: (a) manipulated : Temperature of sodium thiosulphate solution
(b) responding : Time taken until ‘X’ is no longer visible
(c) constant : Concentration and volume of sodium thiosulphate

solution, concentration and volume of sulphuric acid
and size of conical flask

4.2.1 125

Materials: 0.2 mol dm–3 sodium thiosulphate solution, 1 mol dm–3 sulphuric acid
Apparatus: and a piece of white paper with an ‘X’ at the centre

250 cm3 conical flask, 50 cm3 measuring cylinder, 10 cm3 measuring
cylinder, stopwatch, thermometer, Bunsen burner, tripod stand and
wire gauze

Procedure:

1. Using a measuring cylinder, measure and pour 50 cm3 of 0.2 mol dm–3 sodium thiosulphate
solution into a clean and dry conical flask.

2. Leave the solution for 5 minutes.
3. Measure and record in the table the temperature of the sodium thiosulphate solution.
4. Place the conical flask on the ‘X’ on the white paper (Figure 4.10).

Conical flask

Sodium thiosulphate White paper with ‘X’
solution

Figure 4.10
5. Measure and quickly pour 5 cm3 of 1 mol dm–3 sulphuric acid into the sodium thiosulphate

solution and start the stopwatch simultaneously.
6. Observe the ‘X’ from the mouth of the conical flask (Figure 4.11).

Eye

Conical flask

Sodium thiosulphate White paper
solution + sulphuric acid with ‘X’

Figure 4.11

7. Stop the stopwatch once the ‘X’ on the white paper is no longer visible.

8. Record the time taken in the table. Calculate the value of 1 .
time

126 4.2.1

Chapter 4 Rate of Reaction

9. Repeat steps 1 to 8 by replacing the sodium thiosulphate solution at room temperature
with sodium thiosulphate solution heated to 35°C, 40°C, 45°C and 50°C (Figure 4.12).

Thermometer

Wire gauze Conical flask
Tripod stand
Sodium thiosulphate
solution

Heat

Figure 4.12

Result:

Temperature of Room 35 40 45 50

sodium thiosulphate solution (°C) temperature

Time taken until ‘X’ is
no longer visible (s)

1 (s–1)
time

Data analysis:

Draw the following graphs:
(a) graph of temperature against time

(b) graph of temperature against 1
time

Conclusion:
Is the hypothesis accepted? What is the conclusion for this experiment?

Questions:

1. State the factor that affects the rate of reaction in this experiment.
2. How does the factor concerned affect the rate of reaction?
3. State the operational definition of rate of reaction based on this experiment.

4.2.1 127

Experiment 4.2

Aim: To study the effect of concentration of reactants on the rate of reaction

Problem statement: How does concentration of reactants affect the rate of reaction?

Hypothesis: The higher the concentration of reactants, the higher the rate
of reaction.

Variables: (a) manipulated : Concentration of sodium thiosulphate solution
(b) responding : Time taken until ‘X’ is no longer visible
(c) constant : Volume of sodium thiosulphate solution,

concentration and volume of sulphuric acid and
size of conical flask

Materials: 0.20, 0.16, 0.12, 0.08, 0.04 mol dm–3 sodium thiosulphate solutions,
1 mol dm–3 sulphuric acid, distilled water and a piece of white paper

with an ‘X’ at the centre

Apparatus: 250 cm3 conical flask, 50 cm3 measuring cylinder, 10 cm3 measuring
cylinder and stopwatch

Procedure:

1. Using a measuring cylinder, measure and pour 50 cm3 of 0.20 mol dm–3 sodium thiosulphate
solution into a clean and dry conical flask.

2. Place the conical flask on the ‘X’ on the white paper (Figure 4.13).
3. Measure and quickly pour 5 cm3 of 1 mol dm–3 sulphuric acid into the sodium thiosulphate

solution and start the stopwatch simultaneously.
4. Observe the ‘X’ from the mouth of the conical flask (Figure 4.14).

Conical flask Eye

Sodium thiosulphate Conical flask
solution Sodium thiosulphate
solution + sulphuric
White paper acid
with ‘X’
White paper
with ‘X’

Figure 4.13 Figure 4.14

5. Stop the stopwatch once the ‘X’ on the white paper is no longer visible.

6. Record the time taken in the table. Calculate the value of 1 .
time

7. Repeat steps 1 to 6 by replacing the 0.20 mol dm–3 sodium thiosulphate solution with

sodium thiosulphate solution of different concentrations as given in the table.

128 4.2.1

Chapter 4 Rate of Reaction

Result:

Concentration of 0.20 0.16 0.12 0.08 0.04
sodium thiosulphate solution (mol dm–3)

Time taken until ‘X’ is no longer
visible (s)

1 (s–1)
time

Data analysis:

Draw the following graphs:
(a) graph of concentration of sodium thiosulphate solution against time

(b) graph of concentration of sodium thiosulphate solution against 1
time

Conclusion:
Is the hypothesis accepted? What is the conclusion for this experiment?

Questions:

1. State the factor which affects the rate of reaction in this experiment.
2. How does the factor affect the rate of reaction?

Experiment 4.3

Aim: To study the effect of size of solid reactants on rate of reaction

Problem statement: How does the size of reactants affect the rate of reaction?

Hypothesis: The smaller the size of solid reactants, the higher the rate
of reaction.

Variables: (a) manipulated : Size of marble
(b) responding : Time taken to collect 30.00 cm3 of gas

(c) constant : Temperature, mass of marble, concentration and

volume of hydrochloric acid

Materials: Small pieces of marble chips, large pieces of marble chips and
0.1 mol dm–3 dilute hydrochloric acid

Apparatus: 250 cm3 conical flask, 50 cm3 measuring cylinder, rubber stopper with
delivery tube, burette, basin, electronic balance, retort stand with
clamp and stopwatch

4.2.1 129

Procedure:
1. Fill the burette and basin with water. Then, invert the burette into the basin filled with

water and clamp the burette vertically using a retort stand (Figure 4.15).

Vo

Burette Retort
Water stand

Basin

Figure 4.15

2. Adjust the water level in the burette. Observe and record the initial burette reading, V0.
3. Measure 40 cm3 of 0.1 mol dm–3 dilute hydrochloric acid using a measuring cylinder. Pour

the measured acid into a clean and dry conical flask.
4. Weigh 2 g of large pieces of marble chips using an electronic balance. Then, put the 2 g of

marble pieces into the conical flask.
5. Immediately close the conical flask with the rubber stopper which is connected to

a delivery tube. The other end of the delivery tube is placed under the burette (Figure 4.16).
Start the stopwatch.
6. Observe the burette reading. When 30.00 cm3 of gas is collected, stop the stopwatch.
Observe and record the reading on the stopwatch.

Delivery tube Burette Retort
stand
Dilute hydrochloric
acid Basin Water
Marble chips

Figure 4.16

7. Repeat steps 1 to 6 by replacing the large pieces of marble chips with small pieces of
marble chips of the same mass.

130 4.2.1

Result: Chapter 4 Rate of Reaction
Size of marble Time taken to collect 30.00 cm3 of gas (s)

Large pieces of marble chips
Small pieces of marble chips

Data analysis:
1. Compare the time taken to collect 30.00 cm3 of carbon dioxide released from the reaction

using large pieces of marble chips to the reaction using small pieces of marble chips.
2. Compare the rate of reaction of a reaction using large pieces of marble chips to the rate of

reaction of a reaction using small pieces of marble chips.

Conclusion:
Is the hypothesis accepted? What is the conclusion for this experiment?

Question:
How does the size of marble chips affect the rate of reaction between marble and
hydrochloric acid?

Experiment 4.4

Aim: To study the effect of presence of catalyst on rate of reaction

Problem statement: How does the presence of a catalyst affect the rate of reaction?

Hypothesis: Presence of catalyst increases the rate of reaction.

Variables: (a) manipulated : Presence of catalyst
(b) responding : Time taken to collect 30.00 cm3 of gas
Materials: (c) constant : Temperature, volume and concentration of
Apparatus:
hydrochloric acid

Small pieces of zinc, 0.1 mol dm–3 dilute hydrochloric acid and
0.5 mol dm–3 copper(II) sulphate solution

250 cm3 conical flask, 50 cm3 measuring cylinder, rubber stopper with
delivery tube, burette, basin, electronic balance, retort stand with
clamp, spatula and stopwatch

4.2.1 131

Procedure:

1. Fill the burette and basin with water. Then, invert the burette into the basin filled with
water and clamp the burette vertically using a retort stand (Figure 4.17).

CAUTION!

Vo The mixture of hydrogen and
air in the burette can explode
when ignited. Do not ignite
the gas in the burette.

Burette Retort stand

Basin
Water

Figure 4.17

2. Adjust the water level in the burette. Observe and record the initial burette reading, V0.
3. Measure 40 cm3 of 0.1 mol dm–3 dilute hydrochloric acid using a measuring cylinder.

Pour the measured acid into a clean and dry conical flask.
4. Weigh 2 g of zinc pieces using an electronic balance. Then, put the 2 g of zinc pieces into

the conical flask.
5. Immediately close the conical flask with the rubber stopper which is connected to a

delivery tube. The other end of the delivery tube is placed under the burette (Figure 4.18).
Start the stopwatch.

Delivery Burette
tube

Retort stand

Pieces of Basin
zinc Water

Dilute hydrochloric acid

Figure 4.18

6. Observe the burette reading. When 30.00 cm3 of gas is collected, stop the stopwatch.
Record the reading on the stopwatch.

132 4.2.1

Chapter 4 Rate of Reaction

7. Repeat steps 1 to 6 by replacing the 40 cm3 of 0.1 mol dm–3 dilute hydrochloric acid with
a mixture of 40 cm3 of 0.1 mol dm–3 dilute hydrochloric acid and 5 cm3 of 0.5 mol dm–3
copper(II) sulphate solution (Figure 4.19).

Delivery Burette
tube Retort stand

Dilute hydrochloric acid + Basin
copper(II) sulphate solution Water

Zinc pieces

Result: Figure 4.19
Mixture in the conical flask Time taken to collect 30.00 cm3 of gas (s)

Zinc pieces and dilute hydrochloric acid

Zinc pieces, dilute hydrochloric acid and
copper(II) sulphate solution

Data analysis:
1. Compare the time taken to collect 30.00 cm3 of hydrogen gas released from the reaction

using a mixture of zinc and dilute hydrochloric acid to the reaction using a mixture of zinc,
dilute hydrochloric acid and copper(II) sulphate solution as a catalyst.
2. Compare the rate of reaction of a reaction using a mixture of zinc and dilute hydrochloric
acid to a reaction using a mixture of zinc, dilute hydrochloric acid and copper(II) sulphate
solution as a catalyst.

Conclusion:
Is the hypothesis accepted? What is the conclusion for this experiment?

Questions:
1. State the factor which affects the rate of reaction in this experiment.
2. How does the factor affect the rate of reaction?

4.2.1 133

Besides the factors studied in Experiments 4.1 – 4.4, BRAIN
one other factor which affects the rate of reaction is TEASER
pressure. Pressure affects the rate of reaction of a reaction
that involves gaseous reactants. For reactions involving Why is the rate of reaction
gaseous reactants, the rate of reaction usually increases for solid or liquid reactant
when pressure increases. Name two examples of industrial normally not affected
processes which use high pressure to increase their by pressure?
rate of reaction.

Formative Practice 4.2

1. State five factors which affect the rate of reaction.

2. Complete the following statements:

(a) The the temperature of reactants, the higher the rate of reaction.
(b) The the concentration of reactants, the higher the rate of reaction.
(c) The the size of reactants, the higher the rate of reaction.

3. State one factor that only affects the rate of reaction involving reactants in the
form of gas.

4.3 Applications of the Concept of Rate of Reaction

In daily life and industries, factors that
affect the rate of reaction are normally
adjusted to change the rate of reaction of
a reaction. For example, a refrigerator lowers
the temperature of food or drinks kept in it.
This lowering of temperature slows down
food spoilage.

Photograph 4.3 Example of 4.2.1 4.3.1
an appliance which applies the
concept of rate of reaction

134

Chapter 4 Rate of Reaction

Haber Process

In the Haber Process, a mixture of nitrogen gas, N2 and hydrogen gas, H2 in the
ratio of 1:3 at a temperature of 450°C – 550°C and a pressure of 200 atm is passed over
iron filings, Fe which functions as a catalyst to produce ammonia, NH3 (Figure 4.20).

N2 + 3H2 2NH3
Ammonia
Nitrogen Hydrogen

Unreacted
nitrogen
and hydrogen
gases

Nitrogen Mixture of nitrogen and Iron filings (catalyst), Ammonia gas
gas hydrogen gases is temperature cools to form
compressed at a 450°C – 550°C liquid ammonia
Hydrogen pressure of 200 atm
gas Reactor
Compressor
Cooling chamber

Liquid ammonia

Figure 4.20 Production of ammonia using Haber Process

Contact Process

In the Contact Process, sulphur is burnt in an excess of air to produce sulphur dioxide
gas, SO2.

S + O2 SO2
Sulphur dioxide
Sulphur Oxygen

Sulphur dioxide gas mixed with an excess of air at a temperature of 450°C and a
pressure of 1 atm is passed over vanadium(V) oxide, which functions as a catalyst, to
produce sulphur trioxide gas, SO3.

2SO2 + O2 2SO3
Sulphur trioxide
Sulphur dioxide Oxygen

4.3.1 135

Sulphur trioxide gas is dissolved in concentrated sulphuric acid to produce
oleum, H2S2O7.

SO3 + H2SO4 H2S2O7
Oleum
Sulphur trioxide Sulphuric acid

Oleum is diluted with water to produce concentrated sulphuric acid (Figure 4.21).

H2S2O7 + H2O 2H2SO4
Oleum Water Sulphuric acid

Sulphur dioxide, SO2 Sulphur trioxide, SO3
+ oxygen, O2 Concentrated sulphuric acid

Sulphur Waste gases

Dry air Oleum,
H2S2O7
Water
Vanadium(V) oxide Sulphuric acid,
(catalyst) H2SO4

Figure 4.21 Production of sulphuric acid using Contact Process

Factors which increase the rate of reaction in Haber Process and Contact Process are
as follows:

(a) Haber Process (b) Contact Process
Temperature : 450°C – 550°C Temperature : 450°C
Pressure : 200 atm Pressure : 1 atm
Catalyst : Iron filings Catalyst : Vanadium(V) oxide

Formative Practice 4.3

1. (a) Name one life process in the human body which involves the concept of rate
of reaction.

(b) How does the application of rate of reaction influence the life process in
question 1(a)?

2. State the factors which influence the rate of reaction in the following processes:
(a) Haber Process
(b) Contact Process

136 4.3.1

Summary

Rate of Reaction
Change in the quantity of reactant or product per unit time

High rate of reaction Low rate of reaction
Fast reaction Slow reaction

Factors:
• temperature of reactants
• size of solid reactants
• concentration of reactants
• presence of catalyst
• pressure

are applied in

Contact Process
Chapter 4 Rate of Reaction

137
Haber Process

Self-Reflection

After studying this chapter, you are able to:

4.1 Introduction to Rate of Reaction 4.2 Factors Affecting Rate of Reaction
Explain with examples fast reactions Carry out experiments to study
and slow reactions in daily life. factors affecting rate of reaction.
Define the rate of reaction.
Determine the rate of reaction. 4.3 Application of the Concept of
Rate of Reaction
Communicate about the application
of the concept of rate of reaction in
daily life and industries.

Summative Practice 4 Quiz
http://buku-
Answer the following questions: teks.com/
sc5138
1. (a) What is meant by chemical reaction?
(b) Is the rate of reaction affected by pressure?
Explain your answer.

2. A student carried out an Carbon dioxide
experiment to study a factor
which affects the rate of Delivery Burette Retort
reaction between marble tube stand
(calcium carbonate) and dilute Dilute hydrochloric
hydrochloric acid. Figure 1 acid Basin Water
shows the apparatus set-up Figure 1
for the experiment. Marble chips

The student carried out the experiment using marble chips (Set I) and repeated
the experiment by replacing the marble chips with marble powder (Set II). Table 1
shows the results of the experiment for Set I and Set II.

Table 1

Time (s) 0 30 60 90 120 150 180 210

Volume of gas collected 0.00 12.50 23.00 31.00 37.50 42.00 45.00 45.00
in Set I (cm3)

Volume of gas collected 0.00 20.00 32.00 39.00 43.00 45.00 45.00 45.00
in Set II (cm3)

138

Chapter 4 Rate of Reaction

(a) In this experiment, state the:
(i) manipulated variable
(ii) responding variable
(iii) constant variable

(b) State one hypothesis for this experiment.
(c) Based on Table 1, draw two graphs of volume of gas collected against time for

Set I and Set II experiments on the same set of axis on a graph paper.
(d) Based on Set II, calculate:

(i) average rate of reaction for the first minute
(ii) average rate of reaction for the first two minutes
(iii) average rate of reaction in the second minute
(iv) rate of reaction at the 60th second
(v) average rate of reaction for the whole reaction
(e) Based on the results of Set I, calculate the average rate of reaction for the
whole reaction.

Enrichment Practice

3. Digestive enzymes function as biological catalysts to change the rate of
decomposition of complex food molecules into simpler molecules in the digestive
system. What is the use of digestive enzymes other than aiding in the digestion of
food? Figure 2 shows one application of biological catalysts in daily life.

BIOLOGICAL WASHING POWDER

Contains protease and lipase
Optimum action at 40°C
More efficient than ordinary detergent
Do not use boiling water
Do not wash clothes made of silk

Figure 2

(a) Give two examples of biological catalyst in the washing powder.
(b) What is the effect of the biological catalyst towards food stains on clothes?
(c) State one factor that influences the effectiveness of the biological catalyst in

the reaction.
(d) How does this factor influence the action of the biological catalyst?

139

5CHAPTER CARBON
COMPOUNDS

Name two natural carbon compounds that are Malaysia’s exports
which contribute significantly to the economy.

What makes oil palm special compared to other products, such as
soya bean, as a source of cooking oil?

Let’s study

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t )ZESPDBSCPOT
t Alcohol
t 'BUT
t 1BMN PJM

140

Science Bulletin

According to sources from the ESRL’s Global Monitoring Laboratory (GML) of the National Oceanic and
Atmospheric Administration (NOAA), the composition of greenhouse gases including carbon dioxide in
the atmosphere continues to rise. To date, efforts ranging from global bodies like the United Nations (UN)
down to individuals have yet to successfully address the carbon dioxide issue.

Keywords r 4BUVSBUFE GBU
r 6OTBUVSBUFE GBU
r 0SHBOJD DBSCPO DPNQPVOE r 1BMN PJM
r *OPSHBOJD DBSCPO DPNQPVOE r 1BMN LFSOFM PJM
r $BSCPO DZDMF r 'BUUZ BDJE
r 4BUVSBUFE IZESPDBSCPO r (MZDFSPM
r 6OTBUVSBUFE IZESPDBSCPO r )ZESPMZTJT
r "MLBOF r &NVMTJàDBUJPO
r "MLFOF r 4BQPOJàDBUJPO
r "MUFSOBUJWF FOFSHZ TPVSDF r $MFBOTJOH BDUJPO PG TPBQ
r 3FOFXBCMF FOFSHZ TPVSDF r 4VTUBJOBCMF NBOBHFNFOU
r "MDPIPM
r &TUFSJàDBUJPO

141

5.1 Introduction to Carbon Compounds

Carbon Compounds in Nature Carbon compounds

Carbon compounds are compounds

which contain the element carbon, C.

Carbon compounds can be divided into

two groups, namely organic carbon Organic carbon Inorganic carbon
compounds and inorganic carbon compounds compounds
compounds (Figure 5.1).

originate from originate from

BRAIN Living things Non-living things
TEASER

If compound X contains Petroleum, Carbon dioxide in
the carbon element, is silk, the atmosphere
compound X an organic charcoal
carbon compound Decay Burning
or an inorganic carbon Respiration of fuels
compound?
Limestone, Respiration Photosynthesis
carbon dioxide
Are eaten by Green plants

Dead Form Fossil fuels
Organisms (petroleum, natural gas, coal)

Figure 5.1 Organic carbon compounds
and inorganic carbon compounds

Carbon Cycle

The carbon cycle shows how carbon elements are recycled through the formation
or decomposition of carbon compounds in living things and organic substances in the
environment through processes such as respiration, combustion, decomposition and
photosynthesis (Figure 5.2).

Carbon dioxide in
the atmosphere

Decay Burning
Respiration of fuels

Respiration Photosynthesis

Are eaten by Green plants

Dead Form Fossil fuels
Organisms (petroleum, natural gas, coal)

Figure 5.2 Carbon cycle
142 5.1.1 5.1.2

Chapter 5 Carbon Compounds

Carbon dioxide is released into the atmosphere through three main processes:

(a) Respiration
Carbon dioxide is a carbon compound which is released into the atmosphere through
the respiration of all living things including animals, plants and microorganisms.

(b) Combustion
Burning of fossil fuels releases carbon dioxide into the atmosphere. Natural
phenomena such as volcanic eruptions and forest fires also release carbon dioxide
into the atmosphere.

Photograph 5.1 Smoke from Photograph 5.2 Smoke from forest fire
petrol combustion

(c) Decomposition
During the process of decomposition by decomposers such as bacteria and fungi,
carbon dioxide is released into the atmosphere.

Carbon dioxide is absorbed by Light Carbon dioxide
green plants from the atmosphere to energy Oxygen
carry out photosynthesis (Figure 5.3).
The importance of photosynthesis includes: Photosynthesis
(happens in
• enabling green plants to make their chlorophyll)
own food
Glucose
• providing food to animals
• increasing the oxygen content in the air
• removing excess carbon dioxide from the

air to maintain the carbon dioxide content
in the air

Figure 5.3 Photosynthesis

Water

143

5.1.2

Activity 5.1 21st Century Skills

To illustrate the carbon cycle in the form of a diagram • ICS
Instructions • Project-based activity
1. Complete the carbon cycle diagram in Figure 5.4.

Factory Plant

Animal Rubbish

SOYA
KICAP

SOYA SOYA

Algae and
aquatic animals

Figure 5.4
2. Present and display your illustration of the carbon cycle to the class.
3. Justify the enhancements or changes made to your group’s illustration of the carbon cycle.

Formative Practice 5.1 5.1.2

1. What is organic carbon compound?
2. What is inorganic carbon compound?
3. Give two examples of inorganic carbon compounds.
4. What is carbon cycle?
5. State the importance of carbon cycle.

144

Chapter 5 Carbon Compounds

5.2 Hydrocarbons

Hydrocarbon compounds are organic carbon compounds made up of only carbon
and hydrogen elements.

Hydrocarbon Compounds from Natural Sources

The formation of hydrocarbon compounds from natural resources are shown in
Figures 5.5 and 5.6.

Sea Sea
Seabed

Seabed Mud and Fossils of
stone animals
and plants
Remains of dead marine life buried Over millions of years, these
in the seabed. remains are buried deeper and
deeper into the seabed under
thick layers of rock and mud.

Sea

Natural gas The combined effects of pressure exerted by the
Petroleum layers of sand and mud, heat absorbed from the
surroundings, and decomposition caused by
bacteria changes the buried remains into
petroleum and natural gas.

Figure 5.5 Formation of petroleum and natural gas

Coal

Millions of years ago, the Over millions of years, the The combined effects of pressure exerted
remains of dead plants remains become buried deeper by the layers of rock, heat absorbed from
were naturally buried and deeper into the ground the surroundings, and decomposition
underground. under thick layers of rocks. caused by bacteria changes the buried
plant fossils into coal.
5.2.1
Figure 5.6 Formation of coal

145

Fractional Distillation of Petroleum Science

Petroleum is a mixture of hydrocarbons. This mixture Fractional
of hydrocarbons needs to be separated through the distillation in a
fractional distillation process before the petroleum distillation tower at
fractions can be used. Fractional distillation is used an oil refinery and
because the petroleum fractions have different uses of different
boiling points. petroleum fractions.
http://buku-teks.com/sc5146

Activity 5.2 21st Century Skills

To separate crude oil into four different petroleum fractions using • TPS
fractional distillation • ISS

Materials Safety Precautions
Crude oil, wooden splinter, ice, water and glass wool
• Wash your hands with soap
Apparatus and water if you get crude
Measuring cylinder, boiling tube, retort stand, test tubes, oil on your hands.
test tube rack, beaker, rubber stopper with delivery tube,
thermometer (0oC – 360oC), Bunsen burner and • Heating crude oil releases
evaporating dishes petroleum vapour which is
highly flammable.

Instructions CAUTION!

1. Fill a boiling tube with 10 cm3 of crude oil. • Use crude oil only.
2. Prepare the apparatus set-up (Figure 5.7). • Do not substitute crude oil

Thermometer with any other fuel.
(0°C – 360°C)

Retort stand

Delivery tube

Boiling tube Test tube
Crude oil Ice

Glass wool

Heat

Distillate
Figure 5.7 Fractional distillation of petroleum

146 5.2.1

Chapter 5 Carbon Compounds

3. Heat the crude oil in the boiling tube gently from room temperature to 80ºC.
4. Stop heating the crude oil when its temperature reaches 80ºC. Continue the heating process

when its temperature drops below 80ºC.
5. When there is about 1 cm3 of distillate collected in the test tube, replace the test tube

with another empty test tube.
6. Label the distillate collected from room temperature to 80ºC as Fraction 1.
7. Repeat step 3 to collect three more fractions of petroleum at the following ranges

of temperatures:
(a) 80ºC – 150ºC with the collected distillate labelled as Fraction 2
(b) 150ºC – 230ºC with the collected distillate labelled as Fraction 3
(c) 230ºC – 250ºC with the collected distillate labelled as Fraction 4
8. Observe and record the colour of each of the fractions labelled 1, 2, 3 and 4.
9. Pour each petroleum fraction into separate evaporating dishes.
10. Observe and compare the rate of flow or viscosity of each petroleum fraction.
11. Record the viscosity of each petroleum fraction obtained.
12. Ignite each petroleum fraction with a burning splinter. Compare and record how flammable
each fraction is.

Observation

Fraction 1234

Range of boiling points 30oC – 80oC 80oC – 150oC 150oC – 230oC 230oC – 250oC

Colour

Viscosity

Flammability

Questions

1. Name the method of separation used in this activity.
2. Is petroleum a compound or a mixture? Give your reasons.
3. Based on the information from Science Info on page 146, name the distillate obtained

from the fractions labelled as follows:
(a) Fraction 1:
(b) Fraction 2:
(c) Fraction 3:
(d) Fraction 4:
4. What characteristic of the petroleum fractions is applied in the fractional distillation
of petroleum?

5.2.1 147

Saturated and Unsaturated Hydrocarbons

Figure 5.8 shows two types of hydrocarbon compounds, namely saturated
hydrocarbons and unsaturated hydrocarbons.

Hydrocarbon compounds

Saturated hydrocarbons Unsaturated hydrocarbons

Have single covalent bonds Have at least one double covalent bond
between carbon atoms (C–C) (C C) or triple covalent bond (C C)
between carbon atoms

HHH HHH
HCC CH HCC C H

HHH H
Example: Alkane Example: Alkene

Figure 5.8 Hydrocarbon compounds

Homologous Series

In organic chemistry, a homologous series is made up of a specific group of organic
compounds which have similar chemical properties. Examples of homologous series are
the alkane and the alkene.

Alkane Single covalent bond

Alkanes are saturated hydrocarbon compounds. Each carbon HHH
atom in an alkane molecule forms single covalent bonds with HCC CH
other carbon atoms (Figure 5.9).
HHH
As alkane is a homologous series, each member of the alkane Figure 5.9 Alkane
homologous series can be represented by the general formula
Cn H2n+2 where n = 1, 2, 3, … HHH
HCC CH
Alkene
H
Alkenes are unsaturated hydrocarbon compounds. Each alkene Double covalent bond
molecule has at least one double covalent bond between two Figure 5.10 Alkene
carbon atoms (Figure 5.10).

As alkene is a homologous series, each member of the alkene
homologous series can be represented by the general formula
Cn H2n where n = 2, 3, …

148 5.2.2

Chapter 5 Carbon Compounds

The names of the first six members of alkane and first five members of alkene are given
in Table 5.1.

Table 5.1 Names of alkanes and alkenes

Number of carbons, n Alkane Alkene

1 Methane –

2 Ethane Ethene

3 Propane Propene

4 Butane Butene

5 Pentane Pentene

6 Hexane Hexene

Activity 5.3 21st Century Skills

To build and name molecular models of alkane and alkene • ICS, ISS
Materials • Project-based activity

Environmental-friendly materials for building model such as waste paper and wooden splinters

Instructions

1. Carry out this activity in groups.
2. Build and name models of the following alkane and alkene molecules using used materials:

(a) first 6 members of the alkane homologous series
(b) first 5 members of the alkene homologous series
3. Present your built models to the class.

Alternative Energy and Renewable Energy Sources in
Daily Life

Fossil fuels such as petroleum, coal and natural gas are non-renewable energy sources
which are fast depleting. As such, alternative energy sources are becoming increasingly
important in supplying the energy for daily life.

Alternative energy sources are sources of energy that will not deplete easily such
as nuclear energy or other renewable energy sources. Examples of renewable energy
sources are as follows:

• solar energy • geothermal energy
• wind energy • tidal energy
• hydroelectric energy • wave energy
• biomass energy

Many countries, including Malaysia, have the potential to build nuclear power
stations to obtain energy. The advantages and disadvantages of building nuclear power
stations should be taken into consideration before any decision is made.

5.2.2 5.2.3 149

Activity 5.4

To produce methane gas from school canteen food waste 21st Century Skills
Instructions
• ICS, ISS, TPS, STEM
• STEM project-based

activity

1. Carry out this activity in groups.
2. Gather information related to alternative energy and renewable energy sources in daily life.
3. Read and understand the following information:

Rubbish disposal sites release carbon dioxide and methane gases as a result of organic
waste decay. There are some countries which use methane gas to generate electrical energy.

4. Gather and analyse ways to produce methane gas from Safety Precautions
food waste from the Internet.
Be careful when collecting the
5. Plan and carry out a project using the STEM approach to methane gas.
produce methane gas from the decay of food waste in
your school canteen. CAUTION!

6. Present your group project to the class. Methane gas is highly
flammable.

Formative Practice 5.2

1. What is hydrocarbon?
2. State one similarity and one difference between saturated and unsaturated

hydrocarbons.
3. Name one gas which is produced from food waste decay to generate

electrical energy.

5.3 Alcohol

Alcohol is an organic carbon compound which contains carbon, hydrogen and oxygen
elements. Alcohol is prepared through the fermentation process by using the action of
yeast on food containing glucose or starch such as sugar, grapes, apples, sugarcane, rice,
wheat, potato and barley.

150 5.2.3 5.3.1

Chapter 5 Carbon Compounds

Alcohol Preparation Process

In the fermentation process, the zymase in yeast converts glucose into ethanol and
carbon dioxide as in the following equation:

Zymase (enzyme in yeast) Ethanol + Carbon dioxide

Glucose

Activity 5.5 21st Century Skills

To prepare ethanol through fermentation • TPS
Materials • Inquiry-based activity

Distilled water, yeast, sugar, starchy substances such as bread and rice, fruits such as banana and
apple, porcelain chips and limewater

Apparatus

Beaker, glass rod, conical flask, measuring cylinder, delivery tube with stopper, test tube,
distillation flask, Liebig condenser, thermometer, Bunsen burner, tripod stand and wire gauze

Instructions

1. Carry out this activity in groups.
2. Your teacher will instruct each group to prepare either apparatus set-up A, B or C as follows:

Apparatus set-up A Procedure

Conical flask Test tube (a) Put 100 g of sugar and 50 cm3 of
Limewater distilled water into a beaker. Stir the
Sugar solution mixture with a glass rod until it forms
+ yeast a sugar solution.

Figure 5.11 (b) Add 10 g of yeast into the sugar
solution and pour the mixture into a
conical flask.

(c) Prepare the apparatus set-up
(Figure 5.11).

Apparatus set-up B Procedure

Test tube (a) Place 100 g of starchy substance like
bread and 50 cm3 of distilled water in
Conical flask a beaker. Stir the mixture with a
glass rod.
Mixture of bread, Limewater
yeast and (b) Add 10 g of yeast into the mixture and
distilled water pour the mixture into a conical flask.

Figure 5.12 (c) Prepare the apparatus set-up
(Figure 5.12).

5.3.1 151

Apparatus set-up C Procedure

Conical flask Test tube (a) Place 100 g of fruits such as mashed
Limewater bananas and 50 cm3 of distilled water in
Mixture of banana, a beaker. Stir the mixture with a
yeast and distilled glass rod.
water
(b) Add 10 g of yeast into the mixture and
Figure 5.13 pour the mixture into a conical flask.

(c) Prepare the apparatus set-up
(Figure 5.13).

3. Keep apparatus set-ups A, B Thermometer
and C in the laboratory for
a week. Observe and record Water bath Water outlet
changes in the conical flask
mixture and the limewater in Liebig
the test tube. condenser

4. After one week, filter the Filtrate xxxxxxxxxxxxxxxxxxxxx Water
mixture into a conical flask inlet
and pour the filtrate into a Porcelain Heat
distillation flask. chips

5. Distill the contents in the Distillate
distillation flask using the
apparatus set-up shown in Figure 5.14
Figure 5.14.

6. Collect the distillate at a
temperature of 78ºC.

7. Observe and record the colour
and smell of the collected
distillate in the table.

Observation

Substance Observation

Mixture in apparatus Beginning of activity End of activity
set-up A, B or C
Limewater – Colour:
Smell:
Distillate

Questions

1. What product turns the limewater cloudy?
2. What is the purpose of the distillation process in this activity?
3. What is the principle used to separate ethanol from the products of fermentation

through distillation?

152 5.3.1

Chapter 5 Carbon Compounds

The Physical and Chemical Properties of Alcohol

The physical properties of alcohol are as follows:
• colourless
• liquid at room temperature
• has a distinctive smell
• the boiling point increases when its
number of carbon atoms increases
• the solubility in water decreases when
its number of carbon atoms increases
Apart from these physical properties,

carry out Activity 5.6 to study the
physical and chemical properties of alcohol. Photograph 5.3 Use of alcohol as an

antiseptic which is applied before an injection

Activity 5.6 21st Century Skills

To study the physical and chemical properties of ethanol • CPS, ISS
• Inquiry-based activity

Materials

Ethanol, ethanoic acid, concentrated sulphuric acid, limewater, dry cobalt chloride paper, matches
and water

Apparatus

Boiling tube, measuring cylinder, delivery tube, dropper, evaporating dish, test tube holder,
filter funnel, beaker, test tube, retort stand, connecting tube and Bunsen burner

Instructions

A. Physical properties of ethanol

Observe and record the following Connecting Delivery tube
physical properties of ethanol: tube Test tube

• colour Filter
• state of matter at room temperature funnel
• smell
• solubility in water

B. Combustion Evaporating
1. Measure 2 cm3 of ethanol using a dish

Ethanol Limewater

measuring cylinder and pour into an Figure 5.15
evaporating dish.

2. Ignite the ethanol in the evaporating dish (Figure 5.15).

3. Observe and record the colour of the flame.

4. Test the gas released with limewater.

5. Test the droplets of liquid formed on the filter funnel with dry cobalt chloride paper.

C. Esterification

1. Measure 2 cm3 of ethanol and 2 cm3 of ethanoic acid using a measuring cylinder and pour
both liquids into a boiling tube (Figure 5.16(a)). Shake the boiling tube.

5.3.2 153

Dropper Test tube holder

Ethanoic acid Concentrated
sulphuric acid

Ethanol Water
(d)
Heat
(a) (b) (c) CAUTION!

Figure 5.16 Concentrated sulphuric acid
is very corrosive. Its use is
6. Add five drops of concentrated sulphuric acid into the limited within the fume
boiling tube mixture (Figure 5.16(b)) in a fume chamber. chamber.
Shake the boiling tube.
Observation
7. Heat the mixture for several minutes (Figure 5.16(c)).
8. Pour the mixture into a beaker filled with water Observation

(Figure 5.16(d)). Observe and record the characteristics Observation
of the product.

Observation
A. Physical properties of ethanol

Physical property of ethanol
Colour
State of matter at room temperature
Smell
Solubility in water

B. Combustion

Characteristic
Colour of flame
Change(s) to limewater
Change(s) to dry cobalt chloride paper

C. Esterification

Characteristic
Smell of product
Solubility of product in water

Questions
1. What is produced from the combustion of alcohol?
2. (a) What is produced from the reaction between ethanol and ethanoic acid?

(b) What are the physical properties of the product of the reaction between ethanol and
ethanoic acid?

3. What is the function of sulphuric acid in the process of esterification?

154 5.3.2

Chapter 5 Carbon Compounds

Uses of Alcohol in Daily Life

Alcohol is widely used in various fields in daily life as follows:

Fuel

Alcohol is a good fuel because this organic carbon compound is highly flammable,
burns with a blue flame and produces a complete and clean combustion without soot.
For example, alcohol is used as a biofuel for motorised vehicles in the Philippines.

Medicine

Alcohol is used as an antiseptic and disinfectant to kill microorganisms and it is also
used as a solvent for various types of medicine.

Cosmetics

Alcohol is also used as a solvent for various cosmetics such as perfume, lotion
and lipstick.

Industry

Alcohol is normally used as a solvent in industry because it can dissolve organic
substances that are used to prepare various types of industrial substances such as liquid
cleaners and food. Alcohol is also a reactant in the formation of ester which is used in
food processing, cosmetics, paint and other industries. Ethanediol, on the other hand,
is a type of alcohol used as an antifreeze in industries.

Photograph 5.4 Uses of industrial substances which contain alcohol and ester in daily life

5.3.3 155

Effects of Excessive Alcohol Consumption

Alcohol consumption, especially in excess, causes Click@Web
addiction. Alcohol addiction normally causes social
problems in families and social crimes that disrupt Scientific studies on effects of
societal peace. alcohol consumption
http://buku-teks.com/sc5156
A person who is drunk as a result of excessive
alcohol consumption normally causes various
problems such as dangerous driving and altercations.
Expectant mothers who consume excessive alcohol can
cause defects in their baby known as foetal alcohol
syndrome. Babies with foetal alcohol syndrome
have small-sized head and brain, abnormal face and
stunted growth.

Table 5.2 Adverse effects of excessive alcohol
consumption on health

Part of the body Adverse effects of excessive alcohol consumption

Brain Damage to brain cells as well as compromised coordination
and nervous system cause disruptions to body balance and
difficulty in estimating distance

Eyes Blurred vision

Lungs Increased rate of breathing

Heart • Increased rate of heartbeat
• High blood pressure

Stomach Irritation to stomach wall causes bleeding and ulcers

Liver • Damage to liver cells
• Liver cells die and harden
• Cirrhosis
• Liver cancer

Kidney Kidney damage due to overactive elimination of waste
substances

Urinary bladder Frequent urination

156 5.3.4

Chapter 5 Carbon Compounds

Activity 5.7 21st Century Skills

To produce posters or pamphlets or a scrap book on the effects of • ICS
excessive alcohol consumption on health • Project-based activity

Instructions

1. Carry out this activity in groups.
2. Gather information from various sources about the effects of excessive alcohol consumption

on health.
3. Discuss the information gathered.
4. Prepare posters or pamphlets or a scrap book based on the outcome of your group

discussion.
5. Present and display the posters or pamphlets or a scrap book on the science notice board

in your class or science laboratory.

Formative Practice 5.3

1. What is alcohol?
2. How is alcohol prepared?
3. What is the purpose of distillation in the process of alcohol preparation

through glucose fermentation?
4. State two uses of alcohol in daily life.
5. Why is drunk driving caused by the excessive intake of alcohol a serious

traffic offence?

5.4 Fats

Fat is a type of organic carbon compound which
contains carbon, hydrogen and oxygen elements.
What is the importance of fats as a class of food for
humans? Photograph 5.5 shows various sources of fats
in the human diet.

Milk Coconut oil Groundnut Meat Butter

5.3.4 5.4.1 Photograph 5.5 Sources of fats 157

Fats exist in two states, solid and liquid. Solid fats at room temperature usually
originate from sources of animal fats. For example, chicken, cow, goat and fish. Fat in
the form of liquid is known as oil. Oil normally originates from plants. For example,
palm oil, coconut oil and soya bean oil.

As in hydrocarbons, fats can be divided into saturated fats and unsaturated fats.
The similarities and differences between saturated fats and unsaturated fats are shown
in Figure 5.17.

Saturated fats Unsaturated fats

Similarities

t Organic compounds containing carbon, hydrogen and oxygen
t Do not dissolve in water
t Important source of fatty acids in the body

Differences

Animals Source Plants
Solid State at room temperature Liquid
High Low
Melting point Not maximum
Maximum Number of hydrogen atoms in the molecule Possible
Not possible
Addition of hydrogen atoms to molecule

Figure 5.17 Similarities and differences between saturated fats and unsaturated fats

Effects of Eating Food Containing Excessive Fats on Health

Fats represent an important component of a balanced diet in human nutrition.
Eating of food containing excess fats especially saturated fats will increase the level of
cholesterol in the blood and affect our health.

Saturated fats from animal sources such as cheese, eggs, butter and meat contain
high levels of cholesterol. The importance of cholesterol in the human body includes
building of cell membranes, synthesising bile and sex hormones, and producing
vitamin D in skin that is exposed to sunlight.

158 5.4.2 5.4.3

However, excessive cholesterol in the blood can Chapter 5 Carbon Compounds
affect human health as follows:
Click@Web
(a) Gallstones and jaundice
Excessive cholesterol in the blood can form Information on cholesterol
gallstones which block the bile duct. Blocked http://buku-teks.com/sc5159
bile duct can cause jaundice.

(b) Cholesterol deposited in the inner wall of
arteries and atherosclerosis
Cholesterol that accumulates and deposits on
the inner artery walls causes the artery lumen
to become narrow. This narrowed artery can
disrupt or block flow of blood in a condition
known as atherosclerosis (Figure 5.18).

Normal Cholesterol
lumen build-up

Lumen

Figure 5.18 Cross section of healthy artery
and effect of atherosclerosis on artery

Atherosclerosis can cause hypertension or high blood pressure, stroke (burst or
blocked artery leading to the brain) and fatal heart attack.

Steps to avoid health problems caused by excessive cholesterol in blood include:
• reducing the intake of saturated fats in nutrition
• consuming unsaturated fats which can lower the cholesterol level in blood

Activity 5.8

To gather information on fats 21st Century Skills
Instructions
• ICS
• Discussion

1. Carry out this activity in groups.
2. Gather information from the Internet, print media and other electronic media on

the following:
(a) fat content of various sources in daily life
(b) saturated and unsaturated fats
(c) effects of excessive fat intake on health
3. Discuss the information gathered.
4. Present the outcome of your group discussion to the class using a multimedia presentation.

5.4.3 159

Formative Practice 5.4

1. What are fats?
2. Give one example of fats and the source.
3. State one similarity and one difference between saturated fats and

unsaturated fats.
4. State three health problems caused by food intake which contains excess fats.

5.5 Palm Oil

Structure of Oil Palm Fruit Pulp Shell

Observe the structure of the oil palm Kernel
fruit in Photograph 5.6. The oil palm fruit Photograph 5.6 Structure of
is made up of three parts, namely: oil palm fruit

• pulp (mesocarp) which contains the
most palm oil

• kernel which contains the best
quality palm kernel oil

• shell (endocarp) which does not
contain oil

Activity 5.9 21st Century Skills

To observe the structure of the oil palm fruit and identify the quantity aspect of • TPS
oil from pulp and kernel • Inquiry-based

Materials activity
10 oil palm fruits

Apparatus
Forceps, knife, magnifying glass, press, Bunsen burner, tripod stand, wire gauze and white tile

Instructions

1. Place an oil palm fruit on a white tile. Hold the oil palm fruit using forceps and make
a cross-sectional cut on the oil palm fruit using a knife (Figure 5.19).

160 5.4.3 5.5.1 5.5.2

Chapter 5 Carbon Compounds

2. Observe and sketch the structure of the Knife
oil palm fruit and label the parts in the Oil palm
structure of the oil palm fruit. fruit

3. Wash all the oil palm fruits with water. Figure 5.19
4. Put the oil palm fruits into a beaker filled
Boiling Oil palm fruit
with water and boil the water and the oil water
palm fruits for 20 minutes (Figure 5.20). xxxxxxxxxxxxxxxxxxxxx
5. Remove the oil palm fruits from the beaker
using forceps. Heat
6. Separate the pulp from the shell of the oil
palm fruit (Figure 5.21). Figure 5.20
7. Put the pulp into a press to be squeezed. Pulp
Collect the palm oil extracted from the
pulp in a beaker (Figure 5.22). Shell
8. Cut open the shell and remove the kernel. Figure 5.21
9. Repeat step 7 by replacing the pulp with
the kernel. Press
10. Compare and contrast the quantity of
oil extracted from the pulp and kernel.
Record the quantity of oil collected in
the beaker.

Observation

Sketch and label a cross section of the
oil palm fruit.

Palm oil
Figure 5.22

Oil extracted from Quantity of oil collected
Pulp
Kernel

Questions

1. What is the aim of boiling the oil palm fruits?
2. What is the difference in the quantity of oil extracted from the pulp and the kernel?
3. State the difference in colour of the oil extracted from the pulp with the oil extracted from

the kernel.

5.5.1 5.5.2 161

Sequence in the Industrial Extraction Process of Palm Oil

The sequence in the industrial extraction process of palm oil is shown in Figure 5.23.

Bunch of oil palm fruits

Sterilisation
The whole bunch of oil palm fruits is sterilised with steam at a high pressure and temperature. The heat from
the steam kills microorganisms such as bacteria and fungi which can spoil the oil palm fruits. Steam also
softens the pulp of the oil palm fruits and makes it easier to remove the fruits from the bunches.

Threshing
The oil palm fruits are detached from their bunches in a threshing machine.

Digestion
The oil palm fruits are reheated at a high temperature and pounded by rotating beater arms to separate the pulp
from the shell. The pulp and shell which contain the kernel are then processed separately.

Pulp (Extraction of palm oil (PO)) Kernel (Extraction of palm kernel oil (PKO))
The pulp is squeezed with a hydraulic or spindle The shell which contains the kernel is steamed at a high
press to extract PO. pressure. Then, the kernel is separated. The kernel is
dried and PKO is extracted from it with a hydraulic or
spindle press.

Filtration Filtration
The pulp fibres are separated from the PO through The kernel is separated from the PKO through filtration.
filtration.

Purification PO – Palm oil
t Steam is flowed through the PO to remove odour and eliminate acid which PKO – Palm kernel

causes the PO to become sour. oil
t PO flows through activated carbon to be decolourised.

Pure PO Pure PKO

Figure 5.23 Sequence of the industrial extraction process of palm oil

162 5.5.3