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The equation describes an equilibrium reaction occurring in a closed system - HSC - SSCE Chemistry - Question 16 - 2015 - Paper 1
Question 16
The equation describes an equilibrium reaction occurring in a closed system. X(g) + Y(g) ⇌ 4Z(g) ΔH = +58 kJ Under which set of conditions would the highest yield... show full transcript
Worked Solution & Example Answer:The equation describes an equilibrium reaction occurring in a closed system - HSC - SSCE Chemistry - Question 16 - 2015 - Paper 1
Step 1
Evaluate conditions for maximum yield of Z(g)
Answer
According to Le Chatelier's principle, the yield of products in a reaction at equilibrium can be increased by adjusting temperature or pressure. Since the reaction is endothermic (ΔH = +58 kJ), increasing the temperature will favor the formation of Z(g).
Furthermore, the reaction produces more moles of gas on the product side (4 moles of Z) compared to the reactant side (2 moles of X and Y). Therefore, increasing the pressure will also favor the formation of Z(g).
Thus, we need to identify the conditions with high temperature and high pressure from the options provided.
Checking the options:
(A) 50°C, 100 kPa - Low temperature, low pressure (B) 50°C, 200 kPa - Low temperature, high pressure (C) 300°C, 100 kPa - High temperature, low pressure (D) 300°C, 200 kPa - High temperature, high pressure
The best choice is (D) 300°C and 200 kPa, which provides both high temperature and high pressure, maximizing the yield of Z(g).