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Ammonia is produced in the Haber process - AQA - GCSE Chemistry - Question 7 - 2022 - Paper 2
Question 7
Ammonia is produced in the Haber process. The raw materials for the Haber process are nitrogen and hydrogen. The equation for the reaction is: $$N_2(g) + 3H_2(g) ... show full transcript
Worked Solution & Example Answer:Ammonia is produced in the Haber process - AQA - GCSE Chemistry - Question 7 - 2022 - Paper 2
Step 1
Give the sources of the nitrogen and of the hydrogen used in the Haber process.
Answer
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Nitrogen: The nitrogen can be sourced from air or through the use of nitrogen gas extracted from natural sources.
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Hydrogen: The hydrogen is usually obtained from natural gas (methane) through a process called steam reforming or from water/steam.
Step 2
How does the equation for the reaction show that the atom economy of the forward reaction is 100%?
Answer
The atom economy of the forward reaction is 100% because all atoms in the reactants are converted into the products. In the reaction, two molecules of ammonia are produced from one molecule of nitrogen and three molecules of hydrogen, meaning there are no leftover reactants, thus maximizing atom utilization.
Step 3
Explain how the ammonia produced is separated from the unreacted nitrogen and hydrogen in X.
Answer
The mixture is cooled in X, allowing only the ammonia to liquefy as it condenses at room temperature while the unreacted nitrogen and hydrogen remain in gas form. This method effectively separates ammonia from the unreacted gases.
Step 4
Step 5
Explain why these conditions are chosen for economical production of ammonia in the Haber process.
Answer
The conditions of 450 °C and 200 atmospheres are chosen because:
- Rate of Reaction: Higher temperatures increase the reaction rate due to more frequent collisions among reactants.
- Position of Equilibrium: The exothermic nature of the reaction suggests that lower temperatures would favor product formation, but higher temperatures have been found to optimize overall reaction time and cost-efficiency.
- Cost Efficiency: High pressures (>200 atm) tend to increase costs due to equipment durability and energy consumption. Therefore, 200 atmospheres is a balanced choice that enhances yield while maintaining economic feasibility.