Consider the reaction

A\(_{(s)}\) + 2B\(_{(g)}\) → 2C\(_{(aq)}\) + D\(_{(g)}\)

What will be the effect of a decrease in pressure on the reaction?

  • A the equilibrium will shift
  • B rate of forward reaction will increase
  • C rate of backward reaction will increase
  • D rates of forward and backward reaction are not affected
jamb 2019chemistry

The correct answer is C. rate of backward reaction will increase

Given: The equation below

A\(_{(s)}\) + 2B\(_{(g)}\) → 2C\(_{(aq)}\) + D\(_{(g)}\)

According to Le Chatelier's Principle:

Pressure changes affects only the gaseous reactants and products

There must be different amount of gaseous particles on both sides.

Generally; a decrease in the pressure shifts the equilibrium position in favor of the side with larger volume of gases.

I.e  rates of backward reaction.

NB: This is a correction to the video explanation.

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