For the equilibrium reaction PCl5(g) (equilibrium arrow)-> PCl3(g) + Cl2(g) explain the effect of increasing the concentration of Chlorine gas using the equilibrium constant.

Kc=[Cl2(g)][PCl3(g)]/[PCl5(g)] for this reaction. The rate constant is not affected by changes in concentration and hence an increase in the concentration of Chlorine causes an increase in the concentration of PCl5(g) to restore equilibrium. This is in accordance with Le Chatelier's principle (change in the system causes shift in equilibrium to oppose it) as the equlibrium has shifted towards the reactant side of the equation.