Question

The degree of dissociation of $PC{I}_5\left(g\right)\rightleftharpoons PC{I}_3\left(g\right)+C{I}_2\left(g\right)$ , decreases with increase in ______ at equilibrium?

• A. temperature
• B. volume
• C. pressure
• D. concentration

Answer 1

The correct option is C pressure

The degree of dissociation of $\left[PC{l}_5\right(g)\rightleftharpoons PC{l}_3(g)+C{l}_2(g\left)\right]$ , decreases with increase in pressure at equilibrium. When pressure is increased, the equilibrium will shift in the backward direction. This decreases the degree of dissociation.

Note: The number of moles of gaseous reactants are lower than the number of moles of gaseous products. When pressure is increased, the equilibrium will shift in the reverse direction so that there is decrease in the number of moles of gaseous species. This decreases the pressure and nullifies the effect of increase in the pressure. It is in accordance with Le Chatelier's principle.