The value of the equilibrium constant, Kc, at a certain temperature is 4.20 x 10-2. Would the reaction as represented by the chemical equation favor reactants or products? Enter Product or Reactant.

Question

PCl5(g) = PCl3(g)+Cl2(g)

Answer 1

Kc = (PCl3)(Cl2)/(PCl5) = 4.2 x 10^-2
With Kc equal to less than 1, that means that the numerator is smaller than the denominator and that means the reactants will be larger than the products. A second reason, and you need to Kc value, all materials are gaseous and the side with the smaller number of moles is the preferred side if pressure rises.