The balanced equation below represents the reaction used in the Haber process to produce ammonia - NSC Physical Sciences - Question 6 - 2019 - Paper 2
Question 6
The balanced equation below represents the reaction used in the Haber process to produce ammonia.
\[ N_2(g) + 3H_2(g) \rightleftharpoons 2NH_3(g) \quad \Delta H < 0... show full transcript
Worked Solution & Example Answer:The balanced equation below represents the reaction used in the Haber process to produce ammonia - NSC Physical Sciences - Question 6 - 2019 - Paper 2
Step 1
6.1 Write down the meaning of the double arrow used in the equation above.
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Answer
The double arrow in the equation indicates that the reaction is reversible, meaning both forward and reverse reactions can occur, allowing the products to convert back into reactants.
Step 2
6.2 Give ONE reason why ammonia is removed from the reaction vessel as quickly as it forms.
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Answer
Ammonia is removed quickly to favor the forward reaction and increase its production, preventing the decomposition of NH₃ back into N₂ and H₂.
Step 3
6.3 Write down the percentage yield of ammonia at a temperature of 450 °C and a pressure of 200 atmospheres.
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Answer
At 450 °C and a pressure of 200 atmospheres, the percentage yield of ammonia is 20%.
Step 4
6.4.1 For a given pressure, the yield of ammonia at 500 °C is lower than that at 350 °C.
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Answer
At 500 °C, the forward reaction is less favored due to higher temperatures favoring endothermic reactions, resulting in a lower yield of ammonia compared to 350 °C.
Step 5
6.4.2 For a given temperature, the yield of ammonia at 350 atmospheres is much higher than at 150 atmospheres.
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Answer
Increasing the pressure to 350 atmospheres shifts the equilibrium toward the production of ammonia, thus increasing its yield as the reaction favors the side with fewer gas moles.
Step 6
6.5.1 Calculate the maximum number of moles of NH₃(g) that can be obtained in this reaction.
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Answer
The balanced reaction shows that 1 mole of N₂ reacts with 3 moles of H₂ to produce 2 moles of NH₃. Therefore, using 6 moles of N₂ (which requires 18 moles of H₂), the maximum number of moles of NH₃ produced is:
Maximum moles of NH3=6extmolesofN2×1 mole of N22 moles of NH3=12 moles of NH3
Step 7
6.5.2 The above reaction now takes place in a 500 cm³ container at a temperature of 350 °C and a pressure of 150 atmospheres. Use the graph above and calculate the equilibrium constant, Kc, for this reaction under these conditions.
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Answer
To calculate the equilibrium constant (Kc), use the concentrations at equilibrium:
Convert 500 cm³ to dm³:
500extcm3=0.5extdm3
Using the concentrations from the graph, substitute into the expression:
Kc=[N2][H2]3[NH3]2
Calculate the equilibrium concentrations from the graph and solve for Kc.
