Question 1a

Marks: 5

a)

The Arrhenius equation can be written as:

$k = A e^{\frac{- E_{a}}{R T}}$

State what each of the following terms represents, including units where applicable.

A
E_a
R
T

[5]

Key Concepts

The Arrhenius Equation

Question 1b

Marks: 1

b)

Rearrange the Arrhenius equation given in part (a) to make A the subject.

[1]

Key Concepts

The Arrhenius Equation

Question 1c

Marks: 1

c)

State how the rate constant, k varies with temperature, T.

[1]

Key Concepts

The Arrhenius Equation

Question 1d

Marks: 1

d)

State how the activation energy, Ea, varies with rate constant, k.

[1]

Key Concepts

The Arrhenius Equation

Question 2a

Marks: 3

a)

The Arrhenius equation can also be written in natural logarithmic forms.

$\ln k = \ln A - \frac{E a}{R T}$

A plot of ln k against $\frac{1}{T}$ gives a straight-line graph of the type y = mx + c.

Complete the table below which relates the terms from the natural logarithmic Arrhenius equation to the equation of a straight line.

Straight-line term	Arrhenius term
y	ln k
m
x
c

[3]

Key Concepts

Graphing the Arrhenius Equation

Question 2b

Marks: 2

b)

A graph of ln k against $\frac{1}{T}$ is shown below.

Calculate the gradient of the straight line.

[2]

Key Concepts

Graphing the Arrhenius Equation

Question 2c

Marks: 1

c)

Using section 2 of the data booklet, calculate the activation energy, Ea for the graph in part b).

[1]

Key Concepts

Graphing the Arrhenius Equation

Question 2d

Marks: 2

d)

Calculate the frequency factor, A, for the graph in part b) to 2 decimal places.

[2]

Key Concepts

Graphing the Arrhenius Equation

Question 3a

Marks: 1

a)

Arrhenius plots for two reactions with different activation energies are shown below.

State which plot shows the reaction with the greatest activation energy.

[1]

Key Concepts

Activation Energy from Rate Constants at Different Temperatures

Question 3b

Marks: 1

b)

The temperature of both reactions from part a) is increased from 20° to 45°.

Using section 1 of the data booklet, determine which of the reactions will experience the largest change in the rate of reaction.

[1]

Key Concepts

Activation Energy from Rate Constants at Different Temperatures

Question 3c

Marks: 2

c)

The decomposition of hydrogen peroxide into water and oxygen occurs at a slow rate with a rate constant of k = 6.42 x 10^-4 mol dm^-3 s^-1 and at a temperature of 290 K.

When the temperature is increased to 340 K the rate constant k = 6.47 x 10^-2 mol dm^-3 s^-1.

Using sections 1 and 2 of the data booklet, calculate the activation energy for this reaction.

[2]

Key Concepts

Activation Energy from Rate Constants at Different Temperatures

DP IB Chemistry: HL

Topic Questions

16.2 Activation Energy

Question 1a

Key Concepts

Question 1b

Key Concepts

Question 1c

Key Concepts

Question 1d

Key Concepts

Question 2a

Key Concepts

Question 2b

Key Concepts

Question 2c

Key Concepts

Question 2d

Key Concepts

Question 3a

Key Concepts

Question 3b

Key Concepts

Question 3c

Key Concepts

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