Phosphorous pentachloride decomposes according to the reaction



PCl5(g)↽−−⇀PCl3(g)+Cl2(g)



A 12. 3 g sample of PCl5 is added to a sealed 1. 50 L flask and the reaction is allowed to come to equilibrium at a constant temperature. At equilibrium, 34. 8% of the PCl5 remains. What is the equilibrium constant, c , for the reaction?