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JAMB Chemistry 1987 Question 29

Question 29

Chemical Equilibrium

The reaction between sulphur (IV) oxide and oxygen is represented by the equilibrium reaction 2SO2(g) + O2(g) ⇌ 2SO3(g), ΔH = −196 kJ. What factor would influence increased production of SO3(g)?

  1. A.Addition of a suitable catalyst
  2. B.Increase in the temperature of the reaction
  3. C.Decrease in the temperature of the reaction
  4. D.Decrease in the concentration of SO2(g).
Show the answer and explanation

Answer: C (Decrease in the temperature of the reaction)

Explanation

The forward reaction is exothermic, so lowering the temperature shifts the equilibrium to the right, giving more SO3. A catalyst only speeds up reaching equilibrium; it does not change the yield.