Question

The gas phase reaction $2{NO}_2\left(g\right)\to N_2{O}_4\left(g\right)$ is an exothermic reaction. The decomposition of $N_2{O}_4$, in equilibrium mixutre of ${NO}_2\left(g\right)$ and $N_2{O}_4\left(g\right)$, can be increased by:

• A. increasing the pressure
• B. addition of an inert gas at constant pressure
• C. lowering the temperaure
• D. addition of an inert gas at constant volume

Answer 1

The correct option is B addition of an inert gas at constant pressure

Reaction at equilibrium

$N_2{O}_4\rightleftharpoons 2N{O}_2$

(1) According to Le chatelier's principle: Increasing the pressure on a gas reaction shifts the position of equilibrium towards the side with fewer molecules.

So, it will move in backward direction which leads to formation of $N_2{O}_4$from $N{O}_2$.

(2) Addition of an inert gas at constant pressure will increase volume and equilibrium shifts towards more number of molecules i.e. there will be decomposition.

(3) Decomposition of $N_2{O}_4$ is endothermic. So, the reaction will move in forward reaction when the temperature is increased.