Formative Practice 4.1 – Form 5 Science (KSSM) Chapter 4

Question 1:
Give one example of a fast reaction and one example of a slow reaction in daily life.

Example of a fast reaction: Burning of candle
Example of a slow reaction: Photosynthesis
(any other suitable answer is accepted)

Question 2:
Define rate of reaction.

Rate of reaction is the change in the quantity of reactants or products of a reaction per unit time.

Question 3:
Figure 1 shows the graph of volume of hydrogen gas released against time.

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

(a)
Average rate of reaction for the first 2 minutes

$\begin{array}{}\end{array}$

=

(600)

cm

3

120 s

=

60

cm

3

120 s

=0.50
cm
3

s

-1

(b)
Average rate of reaction in the second minute

$\begin{array}{}\end{array}$

=

(6040)

cm

3

(12060) s

=

20

cm

3

60 s

=0.33
cm
3

s

-1

(c)
Average rate of reaction for the whole reaction

$\begin{array}{}\end{array}$

=

65

cm

3

150 s

=0.43
cm
3

s

-1