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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
Step 2
How does the equation for the reaction show that the atom economy of the forward reaction is 100%?
Answer
The equation indicates that all the reactants (1 mole of nitrogen and 3 moles of hydrogen) are converted into product (2 moles of ammonia) without any by-products. Thus, the atom economy is defined as the mass of the desired product divided by the total mass of reactants, which in this case yields 100%.
Step 3
Explain how the ammonia produced is separated from the unreacted nitrogen and hydrogen in X.
Answer
After the reaction, the mixture is cooled so that only ammonia liquefies. This is because the ammonia has a higher boiling point compared to nitrogen and hydrogen. The liquefied ammonia can then be removed, leaving behind the unreacted gases.
Step 4
Determine the percentage yield of ammonia at 450 °C and 500 atmospheres.
Answer
Referring to Table 6, we observe that the yield of ammonia at 420 atmospheres is 43%. For pressures higher than this, the yield will not increase significantly, hence we can extrapolate that the yield at 500 atmospheres will be approximately similar, around 43%.
Step 5
Explain why these conditions are chosen for economical production of ammonia in the Haber process.
Answer
The chosen temperature of 450 °C is a compromise, as higher temperatures increase the rate of reaction but reduce the yield due to equilibrium considerations. The pressure of 200 atmospheres increases the rate of reaction and shifts equilibrium to the right, favoring ammonia production. Using an iron catalyst speeds up the reaction without affecting the equilibrium, thus improving the overall efficiency of the process.