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Ethanol can be manufactured by the reaction between ethene and water - VCE - SSCE Chemistry - Question 1 - 2003 - Paper 1
Question 1
Ethanol can be manufactured by the reaction between ethene and water. This is represented by the equation C₂H₄(g) + H₂O(g) → C₂H₅OH(g) ΔH = 46 kJ mol⁻¹ Which c... show full transcript
Worked Solution & Example Answer:Ethanol can be manufactured by the reaction between ethene and water - VCE - SSCE Chemistry - Question 1 - 2003 - Paper 1
Step 1
Which conditions would produce the highest percentage yield of ethanol at equilibrium?
Answer
To determine the conditions that yield the highest percentage of ethanol at equilibrium, we should consider Le Chatelier's Principle. The forward reaction for the synthesis of ethanol is endothermic, as indicated by the positive enthalpy change (ΔH = 46 kJ mol⁻¹).
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Temperature: Since the reaction is endothermic, increasing the temperature will shift the equilibrium to the right, favoring the production of ethanol. Thus, high temperature is beneficial.
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Pressure: The reaction involves 2 moles of gas on the reactant side (C₂H₄ and H₂O) and 1 mole of gas on the product side (C₂H₅OH). According to Le Chatelier's Principle, an increase in pressure shifts the equilibrium toward the side with fewer moles of gas, which in this case is the product side, leading to a higher yield of ethanol. Therefore, high pressure is also advantageous.
Based on this analysis, the optimal conditions for maximizing the yield of ethanol are high pressure and high temperature, which corresponds to option D.