Equilibrium constant $K_p$ for homogeneous systems (A-level only)

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Question 4
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This question is about the equilibrium reaction for the industrial synthesis of methanol:

CO(g)+2H2(g)⇌CH3OH(g)\text{CO}(\text{g}) + 2\text{H}_2(\text{g}) \rightleftharpoons \text{CH}_3\text{OH}(\text{g})CO(g)+2H2​(g)⇌CH3​OH(g)

a.

State and explain the effect, if any, of an increase in overall pressure on the equilibrium yield of CH3OH\text{CH}_3\text{OH}CH3​OH.

[3]
b.

A 0.600 mol0.600\text{ mol}0.600 mol sample of CO\text{CO}CO is mixed with a 1.600 mol1.600\text{ mol}1.600 mol sample of H2\text{H}_2H2​ in a sealed container at a constant temperature. When equilibrium is reached at a total pressure of 210 kPa210\text{ kPa}210 kPa, the mixture contains 0.400 mol0.400\text{ mol}0.400 mol of CH3OH\text{CH}_3\text{OH}CH3​OH.

Calculate the partial pressure, in kPa\text{kPa}kPa, of H2\text{H}_2H2​ in this equilibrium mixture.

[3]
c.

A different mixture of CO\text{CO}CO and H2\text{H}_2H2​ reaches equilibrium at a different temperature. The table below shows the partial pressures of the gases at equilibrium:

GasPartial pressure / kPa\text{kPa}kPa
CO\text{CO}CO1.25×1021.25 \times 10^21.25×102
H2\text{H}_2H2​2.50×1022.50 \times 10^22.50×102
CH3OH\text{CH}_3\text{OH}CH3​OH5.00×1015.00 \times 10^15.00×101

Give an expression for the equilibrium constant (KpK_pKp​) for this reaction. Calculate the value of the equilibrium constant for this reaction and give its units.

[4]
d.

What is the effect on the value of KpK_pKp​ if the pressure of this equilibrium mixture is increased at a constant temperature?

Select one option:

  • The value of KpK_pKp​ increases.
  • The value of KpK_pKp​ stays the same.
  • The value of KpK_pKp​ decreases.
[1]

Equilibrium constant $K_p$ for homogeneous systems (A-level only) Questions

  1. A Level
  2. /Chemistry
  3. /Equilibrium constant $K_p$ for homogeneous systems (A-level only)