1. ANSWER ALL QUESTIONS
1. The reaction between C and D is represented as follows:
C + D  E
The experiment results are shown in the table below
Exp.
Initial
concentration (M)
Time interval
(minutes)
The change in
concentration of C
(M)[C] [D]
1 0.10 1.0 30 2.5 X 10-3
2 0.10 2.0 30 1.0 X 10-2
3 0.05 1.0 120 5.0 X 10-3
i. Calculate the rate of reaction for each experiment
<1.389 x 10-6
> <5.56 x 10-6
> <6.94 x 10-6
>
ii. Determine the order of reaction with respect to C and D and
write the rate law
iii. State the effect on the reaction rate if the concentration of D
is doubled but the concentration of C remains constant.
Chemistry Unit
Session 2013/2014
Semester 2
Sample QUIZ Paper
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2. Solution:
a) (i) The rate of reaction for each experiment
1)
30
105.2 3
x
= 8.3 x 10-5
M/min @ 1.39 x 10-6
M/s
2)
30
100.1 2
x
= 3.3 x 10-4
M/min @ 5.56 x 10-6
M/s
3)
120
100.5 3
x
= 4.2 x 10-5
M/min @ 6.94 x 10-7
M/s
ii) Rate = k[A]x
[B]y
8.3 x 10-5
= k(0.1)x
(1.0)y
…………………..(1)
3.3 x 10-4
= k(0.1)x
(2.0)y
……………………(2)
4.2 x 10-5
= k(0.05)x
(1.0)y
………………….(3)
(2) /(1)
4 = (2)y
y = 2
(3)/(1)
0.5 = (0.5)x
x = 1
Rate = k[A]1
[B]2
iii) Reaction rate increases four fold.