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

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Question 20
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This question is about the equilibrium:

N2(g)+3H2(g)⇌2NH3(g)\text{N}_2(\text{g}) + 3\text{H}_2(\text{g}) \rightleftharpoons 2\text{NH}_3(\text{g})N2​(g)+3H2​(g)⇌2NH3​(g)

1.

State and explain the effect, if any, of an increase in overall pressure on the equilibrium yield of NH3\text{NH}_3NH3​.

[3]
2.

A 0.500 mol0.500\text{ mol}0.500 mol sample of N2\text{N}_2N2​ is mixed with a 1.200 mol1.200\text{ mol}1.200 mol sample of H2\text{H}_2H2​ in a sealed container at a constant temperature. When equilibrium is reached at a total pressure of 250 kPa250\text{ kPa}250 kPa, the mixture contains 0.300 mol0.300\text{ mol}0.300 mol of NH3\text{NH}_3NH3​.

Calculate the partial pressure, in kPa\text{kPa}kPa, of N2\text{N}_2N2​ in this equilibrium mixture.

[3]
3.

A different mixture of N2\text{N}_2N2​ 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
N2\text{N}_2N2​2.00×1022.00 \times 10^22.00×102
H2\text{H}_2H2​1.50×1021.50 \times 10^21.50×102
NH3\text{NH}_3NH3​4.50×1014.50 \times 10^14.50×101

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]
4.

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)