Question

What is the effect of adding an inert gas 

a) at constant volume 

b) at constant pressure on the following equation: 

PCl₅ (g) PCl₃(g) +Cl₂(g)

Answer 1

 a) At constant vol. the total pressure would increase due to inert gas addition but the conc. of the reactants and products will do not change hence no effect on equilibrium 

b) At const. pressure the vol. of the system would increase. This results in decrease in no. of the moles of reactants per unit vol. Hence, reaction will shift in forward direction.