This question is about reversible reactions and chemical equilibrium - AQA - GCSE Chemistry - Question 6 - 2015 - Paper 3
Question 6
This question is about reversible reactions and chemical equilibrium.
6 (a) (i) What is meant by a closed system?
A closed system is one where nothing can enter or... show full transcript
Worked Solution & Example Answer:This question is about reversible reactions and chemical equilibrium - AQA - GCSE Chemistry - Question 6 - 2015 - Paper 3
Step 1
What is meant by a closed system?
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Answer
A closed system is one where nothing can enter or leave the reaction. This means that the reaction is confined within a vessel, allowing the substances to react without outside interference.
Step 2
Explain why, when a reversible reaction reaches equilibrium, the reaction appears to have stopped.
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Answer
When a reversible reaction reaches equilibrium, the forward and backward reactions occur at the same rate. Therefore, the concentrations of reactants and products remain constant over time, giving the illusion that the reaction has stopped, even though both reactions are still occurring.
Step 3
Name a natural resource from which hydrogen is produced.
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Natural gas is a primary source for producing hydrogen, along with other resources like water and hydrocarbons.
Step 4
Explain how a catalyst speeds up a reaction.
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A catalyst provides an alternative reaction pathway with a lower activation energy. This allows more molecules to react and increases the rate of the reaction without being consumed in the process.
Step 5
What happens to the amount of ammonia produced at equilibrium if the pressure is increased? Give a reason for your answer.
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The amount of ammonia produced will increase when the pressure is increased. This is because the equilibrium shifts to the side with fewer gas molecules, which favors the production of ammonia in the reaction: N₂(g) + 3H₂(g) ⇌ 2NH₃(g).
Step 6
Draw an arrow to show the activation energy on the diagram in Figure 3.
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The activation energy for the forward reaction can be illustrated by drawing a vertical arrow from the reactants to the peak of the energy diagram.
Step 7
How does the diagram in Figure 3 show that the reaction is endothermic?
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The diagram indicates that the energy of the products is higher than the energy of the reactants. This is characteristic of endothermic reactions, which absorb energy.
Step 8
Suggest what effect, if any, increasing the temperature will have on the amount of hydrogen iodide at equilibrium. Give a reason for your answer.
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Increasing the temperature will decrease the amount of hydrogen iodide at equilibrium. This happens because the equilibrium shifts in the direction of the endothermic reaction, favoring the formation of hydrogen and iodine instead of hydrogen iodide.
