For the reaction PCl5 (g) + heat PCl3 (g) + Cl2 (g), what will happen when the volume is increased?

A. There will not be a shift in equilibrium.

B. There will be a shift toward the products.

C. There will be a shift toward the reactants.

D. Not enough information is given

This is an aplication of Le Chatelier Principle. So, if you need further details about the theory behind the answer, search for this subject.

Here is the answer and the explanation.

You can realize that 1 mol of reactant produce 2 moles of products, which means that the trend of the reaction is to increase the volume (at constant pressure) or to increase the pressure (at constant volume). If you realease the pressure by increasing the volume, Le Chaelier principle permit you to predict a displacement of the equilibrium to the right (to the products). This is, because the equilibrium will try to restore (increase) the pressure by producing more molecules.

So, the answer is the option B. There will be a shift toward the products.