1a2 marks
The reversible reaction between carbon dioxide and hydrogen makes methane and water.
carbon dioxide + hydrogen ⇌ methane + water
a)
In a sealed container, this reversible reaction forms a dynamic equilibrium.
What is meant by the term dynamic equilibrium?
Refer to both concentration and rate of reaction in your answer.
[2]
1b6 marks
Higher Only
b)
The student investigates the effect of changing pressure and changing temperature on this reaction.
carbon dioxide + hydrogen ⇌ methane + water
The table shows the percentage yield of methane in the equilibrium mixture under different conditions.
carbon dioxide + hydrogen ⇌ methane + water
The table shows the percentage yield of methane in the equilibrium mixture under different conditions.
| Temperature (in oC) | Pressure (in atmospheres) | ||||
| 100 | 200 | 300 | 400 | ||
| 300 | 35% | 52% | 65% | 80% | |
| 600 | 30% | 46% | 58% | 74% | |
| 900 | 23% | 37% | 47% | 62% | |
| 1200 | 14% | 25% | 36% | 48% | |
Describe what happens to the percentage yield as the pressure and temperature change and explain the effect of increasing the pressure on the rate of reaction.
[6]
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