Ammonia is produced when a mixture of nitrogen and hydrogen reacts - AQA - GCSE Chemistry Combined Science - Question 6 - 2021 - Paper 2
Question 6
Ammonia is produced when a mixture of nitrogen and hydrogen reacts.
The equation for the reaction is:
$$N_2(g) + 3H_2(g) \rightleftharpoons 2NH_3(g)$$
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06.1 ... show full transcript
Worked Solution & Example Answer:Ammonia is produced when a mixture of nitrogen and hydrogen reacts - AQA - GCSE Chemistry Combined Science - Question 6 - 2021 - Paper 2
Step 1
Explain how a sample can be tested to show that carbon dioxide is not present in the mixture.
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Answer
To test for the presence of carbon dioxide in the mixture, you can use limewater (calcium hydroxide solution). If carbon dioxide is present, the limewater will turn milky due to the formation of calcium carbonate. However, if it remains clear, it indicates that carbon dioxide is not present.
Step 2
Explain how a catalyst increases the rate of a reaction.
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Answer
A catalyst increases the rate of a reaction by providing an alternative pathway that has a lower activation energy. This allows more reactant molecules to collide successfully and form products in a given time.
Step 3
Explain how an equilibrium is reached.
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Answer
Equilibrium is reached in a closed system when the rates of the forward and reverse reactions are equal. At this point, the concentrations of the reactants and products remain constant over time, even though both reactions continue to occur.
Step 4
Suggest how the catalyst affects the equilibrium position. Give one reason for your answer.
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Answer
The catalyst does not affect the equilibrium position; it accelerates the rate of both the forward and reverse reactions equally. As a result, the equilibrium concentrations remain the same.
Step 5
What is the effect of increasing the pressure on the reaction to produce ammonia?
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Increasing the pressure will increase the yield of ammonia, as the reaction favors the side with fewer gas molecules (2 moles of NH₃ compared to 4 moles of reactants).
Step 6
Explain the effect of increasing the temperature on the yield of ammonia gas produced at equilibrium.
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Answer
Since the forward reaction is exothermic, increasing the temperature shifts the equilibrium position to favor the endothermic reaction (the reverse reaction), resulting in a decrease in the yield of ammonia gas at equilibrium.
