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

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Question 3
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Sulfur dioxide and oxygen were mixed in a 2:1 2:1\,2:1 mole ratio and left to reach equilibrium in a sealed flask at a temperature of 700 K. The equation for the reaction is:

2SO2(g)+O2(g)⇌2SO3(g)2\mathrm{SO_2(g) + O_2(g) \rightleftharpoons 2SO_3(g)}2SO2​(g)+O2​(g)⇌2SO3​(g)

a.

When equilibrium was reached, the total pressure in the flask was 450 kPa and the mole fraction of SO3(g)\mathrm{SO_3(g)}SO3​(g) in the mixture was 0.40. Calculate the partial pressure of each gas in this equilibrium mixture.

[3]
b.

Give an expression for the equilibrium constant (KpK_pKp​) for this reaction.

[1]
c.

In a different equilibrium mixture, under different conditions, the partial pressures of the gases were: p(SO2)=1.50×102 kPap(\mathrm{SO_2}) = 1.50 \times 10^2\text{ kPa}p(SO2​)=1.50×102 kPa p(O2)=2.50×102 kPap(\mathrm{O_2}) = 2.50 \times 10^2\text{ kPa}p(O2​)=2.50×102 kPa p(SO3)=3.00×102 kPap(\mathrm{SO_3}) = 3.00 \times 10^2\text{ kPa}p(SO3​)=3.00×102 kPa

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

[3]
d.

The enthalpy change for the reaction is -197 kJ mol-1. State the effect, if any, of an increase in temperature on the value of Kp K_p\,Kp​ for this reaction. Justify your answer.

[3]

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)