Question

Consider the given reaction:

$2S{O}_2\left(g\right)+O_2\left(g\right)\leftrightharpoons 2S{O}_3\left(g\right)+heat$

What will happen if the pressure of the reacting system is decreased?

• A. The reaction shifts in the direction of more number of gas molecules.
• B. The reaction shifts in the direction of a lesser number of gas molecules.
• C. A forward reaction will be favored.
• D. The new reaction mixture will contain more of sulphur trioxide.

Answer 1

The correct option is A

The reaction shifts in the direction of more number of gas molecules.

Pressure is one of the factors which affects the chemical equilibrium of the reversible system. If the pressure of the reacting species is decreased then as per Le Chatelier's principle equilibrium shifts to increase the pressure. The side of the reaction with a more number of gas molecules will be favored.

In the case of the formation of sulphur trioxide from sulphur dioxide and oxygen, the backward reaction will be favored and new reaction mixture will contain more amount of the reactants.