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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
Nitrogen is mainly sourced from the air, as it constitutes about 78% of the Earth's atmosphere. Hydrogen is typically derived from natural gas, specifically methane, or through the process of water electrolysis.
Step 2
How does the equation for the reaction show that the atom economy of the forward reaction is 100%?
Answer
The equation shows that all the reactants convert into a single product, ammonia (2NH₃). Since no reactants are wasted and all are transformed into the desired product, the atom economy is 100%.
Step 3
Explain how the ammonia produced is separated from the unreacted nitrogen and hydrogen in X.
Answer
The mixture in X is cooled, which allows the ammonia to liquefy while the unreacted nitrogen and hydrogen remain as gases. This difference in state allows for effective separation, where the liquid ammonia can be collected, leaving behind the gaseous reactants.
Step 4
Determine the percentage yield of ammonia at 450 °C and 500 atmospheres.
Answer
To estimate the yield at 500 atmospheres, we can extrapolate from the data in Table 6. Observing the trend, a pressure of 420 atmospheres yields 43%. Assuming a similar linear relationship, the yield at 500 atmospheres could be estimated slightly higher, likely around 45-48%.
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 to optimize the rate of reaction and position of equilibrium. Higher temperatures increase reaction rates due to more frequent collisions but shift equilibrium to favor reactants. The moderate temperature helps in balancing yield with kinetics. The high pressure increases the reaction rate and shifts equilibrium towards the product side, maximizing ammonia production, while the use of a catalyst lowers activation energy, allowing the reaction to proceed faster at lower energy costs.