Answer to Question #148401 in Organic Chemistry for rhea

Question

A sample of pure PCl5 was introduced into an evacuated vessel at 473 K. After equilibrium was reached, the concentration of PCl5 was found to be 0.5 x 10-1 mol L-1. If Kc is 8.3 x 10-3 what are the concentrations of PCl3 and Cl2 at equilibrium?

Answer 1

PCl₅ = PCl₃ + Cl₂

c(PCl₃) = c(Cl₂) from stoichiometric coefficients

K = c_PCl3*c_Cl2/c_PCl5 = c²_Cl2/c_PCl5 = 8.3*10^-3

c_Cl2 = c_PCl3 = √(Kc*c_PCl5) = √(8.3*10^-3*0.5*10^-1) = √(4.15*10^-4) = 0.0204 mol/L