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6.2 Reversible reactions and dynamic equilibrium

6.2 Reversible reactions and dynamic equilibrium

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Question 6

This question is about reactions between gases.

When deep purple iodine gas is heated, it dissociates to form colourless gaseous iodine atoms.

The equation for this reversible reaction is:

iodine gas⇌iodine atoms \text{iodine gas} \rightleftharpoons \text{iodine atoms} iodine gas⇌iodine atoms

This reversible reaction reaches equilibrium in a sealed container.

a.

How does the equation show that the reaction is reversible?

[1]
b.

Which two statements are correct when the reaction reaches equilibrium?

  • The pressure inside the container continues to increase indefinitely.
  • The rate of the forward reaction is equal to the rate of the reverse reaction.
  • All of the purple iodine gas has reacted to form iodine atoms.
  • The concentration of each substance remains constant.
  • Both the forward and reverse reactions have completely stopped.
[2]
c.

The initial gas in the sealed container is deep purple. Gaseous iodine atoms are colourless.

How will the colour of the gas in the sealed container have changed when equilibrium is reached?

  • The gas will have become a deeper purple.
  • The gas will have become a paler purple.
  • The gas will have become colourless.
[1]
d.

The rate of reaction between gases is affected by changing the pressure.

Complete the sentences:

When the pressure of the reacting gases is increased, the rate of reaction ____________.

This is because at higher pressures the number of particles in a given volume ____________.

This means that the frequency of collisions ____________.

[3]
e.

Give one other way of changing the rate of reaction between gases.

You should not refer to pressure in your answer.

[1]
Markscheme

6.2 Reversible reactions and dynamic equilibrium Questions

  1. GCSE
  2. /Chemistry
  3. /6.2 Reversible reactions and dynamic equilibrium

21 exam-style questions on AQA GCSE Chemistry 6.2 Reversible reactions and dynamic equilibrium, covering 6.2.1 Reversible reactions, 6.2.2 Energy changes and reversible reactions, 6.2.3 Equilibrium, 6.2.4 The effect of changing conditions on equilibrium (HT only), 6.2.5 The effect of changing concentration (HT only), 6.2.6 The effect of temperature changes on equilibrium (HT only), and 6.2.7 The effect of pressure changes on equilibrium (HT only). Each one has a worked solution and a mark scheme showing where the marks go.

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