Question

The degree of dissociation of $PC{l}_5$ _________________.

• A. increases with increasing pressure
• B. decreases with increasing pressure
• C. no effect on change in pressure
• D. decreases with decreasing pressure

Answer 1

The correct option is B decreases with increasing pressure

For the reaction $PC{l}_5\leftrightharpoons PC{l}_3+C{l}_2$

The forward reaction occurs with an increase in the number of moles from $1$ to $2$ and the reverse reaction occurs with a decrease in the number of moles from $2$ to $1$.

When the pressure of the system is increased, the reverse reaction will be favoured to nullify the increase in pressure and the reverse reaction occurs with a decrease in the number of moles.

Thus, the dissociation of $PC{l}_5$ is suppressed.

Hence, the degree of dissociation decreases.