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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. In an exothermic reaction, the concentration of methanol increases as the temperature decreases. From the given graph, we can observe that at lower temperatures, the product concentration (methanol) is higher, indicating that heat is released when methanol is formed.
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 chosen to increase the rate of reaction. While the equilibrium concentration of methanol is higher at lower temperatures, low temperatures result in very slow reaction rates. A balance is needed between achieving a reasonable rate of production and obtaining a high yield, making 520 K a suitable compromise.
Step 3
Explain why, at a given temperature, the use of high pressures results in a greater equilibrium concentration of methanol.
Answer
According to Le Chatelier's principle, increasing the pressure will shift the equilibrium position towards the side with fewer moles of gas. In this reaction, there are 3 moles of reactants (1 mole of CO and 2 moles of H2) and only 1 mole of product (methanol). Therefore, applying high pressure will 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 means that more reactant molecules can acquire the necessary energy to collide successfully, leading to a higher frequency of effective collisions. By reducing the activation energy, the catalyst allows the reaction to proceed faster without being consumed in the process.