The first stage involves a gaseous equilibrium between the reactants (methane and steam), and some gaseous products - AQA - A-Level Chemistry - Question 9 - 2017 - Paper 1
Question 9
The first stage involves a gaseous equilibrium between the reactants (methane and steam), and some gaseous products. Figures 1 and 2 show the percentage conversion o... show full transcript
Worked Solution & Example Answer:The first stage involves a gaseous equilibrium between the reactants (methane and steam), and some gaseous products - AQA - A-Level Chemistry - Question 9 - 2017 - Paper 1
Step 1
Stage 1: Deduction from graph
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Answer
From Figure 1, we observe that the percentage conversion of methane increases as the temperature rises, indicating that the reaction is endothermic. Thus, to achieve higher yields, a higher temperature is favored.
In Figure 2, the percentage conversion decreases as the pressure increases. This suggests that the reaction favors lower pressures because it generates more gaseous moles (1 mole of CH₄ and 1 mole of H₂O yield 2 moles of products).
Step 2
Stage 2: Optimum temperature and explanation
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Answer
The optimum temperature for maximum conversion of methane lies between approximately 780-850°C, as derived from Figure 1 where the conversion slows down past this range and might also lead to unwanted side reactions.
Step 3
Stage 3: Optimum pressure and explanation
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Answer
The optimum pressure should be maintained around 1000-2000 kPa. Higher pressures beyond this range may have diminishing returns concerning conversion due to the properties seen in Figure 2.
