AQA A2 Chemistry C18 Kinetics Kerboodle Answers

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C18.1 The rate of chemical reactions AQA A2 Chemistry C18 Kinetics Kerboodle Answers : Page No. 26

1 A reactant -its concentration decreases with time.

2 1.3×10-³ mol dm^-3 s^-1 to2sf

3

The rate of reaction after 300 seconds.

4 That at time 0 seconds, the gradient will be steeper than that at time 600 seconds.

5 The rate of reaction at the beginning is greatest as the concentration of’ reactants is greatest here a.

18.2 The rate expression and order of reaction AQA A2 Chemistry C18 Kinetics Kerboodle Answers : Page No. 29

1Rate= k[A][B][C]²

2

Br03-(aq) + 5Br-(aq) + (aq) -.3Bra (aq)+ 3H20(l)

Brornate ions bromide ions hydrogen ions bromine Water

a

i BrO₃^–(aq)

1

ii Br^–(aq)

1

iii H⁺(aq)?

2

b

i BrO₃^–(aq)

Double

ii Br^–(aq)

Double

iii H⁺(aq)?

Quadruple

c

i BrO₃^–(aq)

ii Br^–(aq)

5

iii H⁺(aq)

6

iv Br₂(aq)

3

v H₂O(1)

3

d

dm⁹ mol-³ s-¹

3

The rate constant

b  

i L

2

ii M

0

iii N

0

iv H’?

1

c

3

d

dm⁶ mol-² s^-1

1.  

A catalyst

4

It is impossible to tell without experimental data.

nd then decreases as reactants are used up.

18.3 Determining the rate equation AQA A2 Chemistry C18 Kinetics Kerboodle Answers  : Page No. 34

1

a i A

1

ii B?

2

b 3

c

27 mol dm^-3s^-1

d

Rate= k[A][B]²

e No, other species might be involved that have not been investigated.

18.4 The Arrhenius equation AQA A2 Chemistry C18 Kinetics Kerboodle Answers  : Page No. 38

1

a 300 K

36 in 10¹⁹ molecules

b 310 K

13 in 10 ¹⁸ molecules

2

Plot 103.75 kJ mol·¹

18.5 The rate-determining step AQA A2 Chemistry C18 Kinetics Kerboodle Answers  : Page No. 41

1

a B

b F

c Step ii

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Practice questions AQA A2 Chemistry C18 Kinetics Kerboodle Answers  : Page No. 42-43

1 (a

(i)2 or two or second or [E]²

(ii)

1 or one or first or [F]¹ or [F]

(b

i k = 8.6 × 10^-4 / ((3.8 × 10^-2)2 × (2.6 × 10^-2))

= 22.9 (Allow 22.9 – 24 after correct rounding)

Mol^-2 dm⁶ s^-1

ii 6.8(2) × 10^-3 (mol dm^-3 s^-1)

2 2P(g) + 2Q(g) —► R(K) +S(g)

 (a)

Experiment 2 4.5 ×10^-4

Experiment 3 4.5 ×10^-3

Experiment 4 0.043 OR 4.3 ×10^-2

OR 0.044 OR 4.4 ×10^-2

(b) k = 5.0 × 10^-5 / ((2.5 × 10^-2)2 × (1.8 × 10^-2))

= 4.4(4) (allow 40/9)

Mol^-2 dm⁶ s^-1.

.

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