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Methanol is produced on an industrial scale by the catalytic conversion of a mixture of hydrogen and carbon monoxide gases at a temperature of 520 K and a pressure of 50 to 100 atmospheres - VCE - SSCE Chemistry - Question 7 - 2011 - Paper 1
Question 7
Methanol is produced on an industrial scale by the catalytic conversion of a mixture of hydrogen and carbon monoxide gases at a temperature of 520 K and a pressure o... show full transcript
Worked Solution & Example Answer:Methanol is produced on an industrial scale by the catalytic conversion of a mixture of hydrogen and carbon monoxide gases at a temperature of 520 K and a pressure of 50 to 100 atmospheres - VCE - SSCE Chemistry - Question 7 - 2011 - Paper 1
Step 1
Is the reaction exothermic or endothermic? Explain your answer.
Answer
The reaction is exothermic. This can be determined by observing that as the temperature decreases, the yield of methanol increases. According to Le Chatelier's principle, if the temperature of an exothermic reaction is lowered, the system shifts to produce more heat, thus favoring the formation of products, in this case, methanol.
Step 2
Explain why a moderately high temperature of 520 K is used although the equilibrium concentration of methanol is greater at a lower temperature.
Answer
A moderately high temperature of 520 K is used to increase the rate of reaction. While lower temperatures favor the production of methanol at equilibrium, they also slow down the rate at which equilibrium is reached. By operating at a higher temperature like 520 K, the reaction proceeds at a faster rate, allowing for a more efficient production process, even if the equilibrium yield is lower.
Step 3
Explain why, at a given temperature, the use of high pressures results in a greater equilibrium concentration of methanol.
Answer
At a given temperature, increasing the pressure shifts the equilibrium position to favor the side of the reaction with fewer gas molecules. In the reaction CO(g) + 2H2(g) ⇌ CH3OH(g), there are three moles of gas on the reactant side and only one mole of gas on the product side. Thus, higher pressures favor the formation of methanol, increasing its equilibrium concentration.
Step 4
Explain how a catalyst can increase reaction rate.
Answer
A catalyst increases the reaction rate by providing an alternative reaction pathway with a lower activation energy. This allows more reactant molecules to have enough energy to undergo successful collisions, thus accelerating the rate at which equilibrium is reached without affecting the position of the equilibrium.