AQA A Level Chemistry

Topic Questions

5.2 Rate Equations (A Level only)

11 mark

The reaction between iodine and propanone can be catalysed by sulfuric acid. The rate equation shows that this reaction is first order with respect to propanone:

Rate = k [H+] [C3H6O]

Which graph shows that the reaction is first order with respect to propanone?

5-2-rate-equations--mcq--q-no-1

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21 mark

Substances A and B react in solution according to the equation.

                                                           A + 2B → C + 2D

The results of an investigation of the reaction between A and B are shown in this table.

Experiment 

Initial [A] 

/ mol dm–3

Initial [B] 

/ mol dm–3

Initial rate

/ mol dm–3 s–1

1

0.25

0.25

3.5 ×10-4

2

0.25

0.50

To be calculated

The rate equation for this reaction is rate = k [B]

What is the initial rate of reaction for experiment 2?

  • 1.4 × 10-3 mol dm–3 s–1

  • 7.0 × 10-4 mol dm–3 s–1

  • 3.5 ×10-4 mol dm–3 s–1

  • 1.75 ×10-4 mol dm–3 s–1

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31 mark

The rate equation for the reaction between A and B is:

                                                         Rate = k [A] [B]

What are the correct units for the rate constant of this rate equation?

  • mol dm-3 s-1

  • mol2 dm−6 s−1

  • mol−2 dm6 s−1

  • mol-1 dm3 s-1

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41 mark

The Arrhenius equation is shown below.

k space equals space A e to the power of bevelled fraction numerator negative E subscript a over denominator R T end fraction end exponent

Which term from the Arrhenius equation has the incorrect units?

       

   Term      

    Units 

A

Ea 

J mol-1 

B

J K-1 mol-1 

C

K-1

D

No units

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51 mark

An alternative version of the Arrhenius equation is:

                                           ln k =fraction numerator negative E subscript a over denominator R end fraction 1 over T + In A

Which specific term can be calculated from an Arrhenius plot, shown below, using this equation?

5-2-e-q5-aqa-al-chemistry

  • Ea

  • 1 over T

  • R

  • 1 over R

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11 mark

The reaction between iodine and propanone can be catalysed by sulfuric acid. The rate equation for this reaction is:

Rate = k [H+] [C3H6O]

 In reaction 1, the rate of reaction for a mixture of iodine, propanone and sulfuric acid at pH 0.72 was measured.

 Reaction 2 contained the same concentrations of iodine and propanone, but the concentration of sulfuric acid was changed. The rate of reaction for this mixture was found to be a quarter of the rate of reaction 1.

What was the pH of the second mixture?

  • 0.44

  • 0.74

  • 1.02

  • 1.32

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21 mark

Two reactions between A and B were investigated. The results are shown in the table.

Experiment

Initial [A]

/ mol dm–3

Initial [B]

/ mol dm–3

Initial rate

/ mol dm–3 s–1

1

0.25

0.50

0.60

2

0.60

To be calculated

1.20

 

The rate equation is rate = k [A]2 [B]2

What is the initial concentration of B in experiment 2?

  • 0.09 mol dm–3

  • 0.29 mol dm–3

  • 0.65 mol dm–3

  • 0.83 mol dm–3

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31 mark

For the general reaction C + D + E F + G, the rate equation is rate = k [C]2 [D] [E]2.

What factor will the rate of reaction increase by when the concentration of all reactants is doubled?

  • 8

  • 16

  • 32

  • 64

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41 mark

The results of three experiments carried out at a temperature, T1, to investigate the rate of the reaction between compounds H and J are shown in the table.

 

Experiment 1

Experiment 2

Experiment 3

Initial [H] / mol dm-3

0.15

0.21

0.42

Initial [J] / mol dm-3

0.60

0.60

1.80

Initial rate / mol dm-3 s-1

2.84 x 10-5

3.98 x 10-5

7.16 x 10-4

 

Using the data in the table, what is the correct rate equation for the reaction between compounds H and J?

  • Rate = k [H] [J]

  • Rate = k [H] [J]2

  • Rate = k [H]2 [J]

  • Rate = k [H]2 [J]2

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51 mark

In the reaction between compounds L and M at temperature, T1, the initial rate of reaction was found to be 2.96 x 10-2 mol dm-3 s-1.

The rate constant, k, for the reaction is 782 mol-2 dm6 s-1 and the rate equation is:

Rate    = k [L]2 [M]

The initial concentrations of L and M were both y mol dm-3.

What is the correct concentration of L and M?

  • 3.36 x 10-2 mol dm-3 

  • 6.15 x 10-3 mol dm-3

  • 2.98 x 101 mol dm-3  

  • 1.26 x 10-5 mol dm-3 

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11 mark

The reaction between iodine and propanone can be catalysed by sulfuric acid. The rate equation for this reaction is:

Rate = k [H+] [C3H6O]

Which of the following sets of statements is correct about the order of reaction with respect to each chemical involved? 

 

           Iodine 

    Propanone

    Sulfuric acid

 A 

Zero

First

Second

B

First

Zero

First

C

Zero

First

First

D

Zero 

Second

Zero

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21 mark

For the general reaction V + W + X → Y + Z, the rate equation is: 

                                                     rate = k [V] [W] [X]

What will happen to the rate of reaction when the concentration of all three reactants is doubled?

  • Increase by a factor of 2

  • Increase by a factor of 4

  • Increase by a factor of 6

  • Increase by a factor of 8

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31 mark

The general reaction D + E F + G uses an acid catalyst, H.

The rate equation for this fourth order reaction is rate = k [D] [E]2.

Which of the following sets of statements is correct about the order of reaction with respect to each chemical involved.

 

 

D

E

H

A

First

First

Zero

B

First

First

Second

C

First

Second

Zero

D

First

Second

First

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41 mark

Two compounds, X and Y, were reacted together.

The initial rate of reaction when compound X and compound Y were reacted together was measured in a series of experiments.

The temperature was kept constant and the results of the experiments are shown below.

Expt.

Initial [X] / mol dm-3

Initial [Y] / mol dm-3

Initial rate / mol dm-3 s-1

1

0.030

0.020

4.0 x 10-4

2

0.030

0.030

6.0 x 10-4

3

0.060

0.030

1.2 x 10-3

What are the correct orders with respect to X and Y?

 

X

Y

A

Second

Second

B

First

First

C

Second

First

D

First

Second

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51 mark

An investigation into the rate of reaction between compounds A and B was performed.

A + B → Products

The results from three different experiments carried out at a constant temperature are shown:

 

Expt.

Initial concentration of A / mol dm-3

Initial concentration of B / mol dm-3

Initial rate / mol dm-3 s-1

1

0.30

0.50

6.0 x 10-4

2

0.30

0.25

1.5 x 10-4

3

0.60

0.25

3.0 x 10-4

 

The rate equation for this reaction is rate = k [A] [B]2

What is the value of the rate constant, k?

  • 2.0 x 10-3

  • 3.2 x 10-2

  • 8.0 x 10-3

  • 2.7 x 10-2

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