Book 4A Ans

HKDSE CHEMISTRY – A Modern View
(Second Edition)
(Chemistry)
Coursebook 4A
Suggested answers

Chapter 36 Rate of chemical reaction
Page
Number
Class practice
1
Think about
5
Chapter exercise
5
Chapter 37 Factors affecting rate of reaction
Class practice
11
Think about
14
Writing practice
14
Chapter exercise
14
Chapter 38 Molar volume of gases at room temperature and pressure (r.t.p.)
Class practice
21
Self-test
24
Think about
26
Chapter exercise
27
Part exercise
34
Chapter 39 Dynamic equilibrium
Class practice
44
Think about
45
Chapter exercise
46
Chapter 40 Equilibrium constant
Class practice
49
Self-test
53
Think about
53
Try it now
54
Chapter exercise
55
Chapter 41 The effect of changes in concentration and temperature on chemical equilibria
Class practice
64
Think about
67
Chapter exercise
68
Part exercise
76
Chapter 36 Rate of chemical reaction

Class Practice
A36.1 (p.36-3)
(a) Putting a piece of calcium in water
(b) Adding silver nitrate solution to sodium chloride solution

A36.2 (p.36-7)
(a) Rate of formation of NO2(g) == 0.24 mol dm–3 s–1
(b) From the equation, mole ratio of NO2 to N2 = 2 : 1. Rate of consumption of N2(g) =× Rate of formation of NO2(g) =× 0.24 mol dm–3 s–1 = 0.12 mol dm–3 s–1
(c) From the equation, mole ratio of NO2 to O2 = 2 : 2 = 1 : 1. Rate of consumption of O2(g) = Rate of formation of NO2(g) = 0.24 mol dm–3 s–1

A36.3 (p.36-12)
(a) Instantaneous rate of reaction at point A == 3.5 mol dm–3 min–1 Instantaneous rate of reaction at point B == 1.1 mol dm–3 min–1 Instantaneous rate of reaction at point C = 0 mol dm–3 min–1 as the curve has become horizontal starting from the 7th minute.
(b) At the start of the reaction, the rate of reaction is the highest. As the reaction proceeds, the rate of reaction becomes lower and lower and finally it becomes zero.
(c) Average rate of the whole course of reaction == 0.77 mol dm–3 min–1

A36.4 (p.36-13)
(a)

(b) Draw a tangent at time t = 0, then find the slope of the tangent. Initial