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JAMB Chemistry 1994 Question 30

Question 30

Chemical Equilibrium

Which of the following is TRUE of Le Chatelier's Principle for an exothermic reaction?

  1. A.Increase in temperature will cause an increase in the equilibrium constant
  2. B.Increase in temperature will cause a decrease in the equilibrium constant
  3. C.Addition of a catalyst will cause an increase in the equilibrium constant
  4. D.Addition of a catalyst will cause a decrease in the equilibrium constant
Show the answer and explanation

Answer: B (Increase in temperature will cause a decrease in the equilibrium constant)

Explanation

For an exothermic reaction, heating favours the backward (endothermic) reaction, so less product forms and K gets smaller. A catalyst speeds up both directions equally and leaves K unchanged.