Question

At constant pressure, which of the following is true for dissociation of $PC{l}_5$(g) for the addition of inert gases?

• A. Reduces the dissociation of $PC{l}_5$
• B. Increases the dissociation of $PC{l}_5$
• C. Does not affect the degree of dissociation of $PC{l}_5$
• D. Decrease in the formation of $PC{l}_3\left(g\right)$​

Answer 1

The correct option is B Increases the dissociation of $PC{l}_5$

For the reaction $PC{l}_5\left(g\right)\rightleftharpoons PC{l}_3\left(g\right)+C{l}_2\left(g\right)$​, the forward reaction occurs with an increase in the number of moles from 1 to 2. Also, the reverse reaction occurs with a decrease in the number of moles from 2 to 1.

When inert gas is added at constant pressure the partial pressure of the reactants and products decreases and hence the equilibrium will shift in the direction in which there is an increase in the number of moles of gases.


Thus, the addition of inert gas at constant pressure will increase the dissociation of$PC{l}_5$​(g).

As $PC{l}_5$​(g) dissociation is increasing so $PC{l}_3$​(g) formation should increase, hence (d) is wrong.




Option B is correct.