Phosphorus trichloride gas and chlorine gas reacts to form phosphorus pentachloride gas: PCL3(g) +CL2(g) = PCL5(g). A vessel is CHARGED WITH A MIXTURE OF PCL3(g) and CL2(g), which is allowed to equilibrate at 450K. At equlibrium the partial pressures of the three gases are Ppcl3=0.124atm, Pcl2 = 0.157 atm, and Ppcl5 = 1.30 atm. (a) what is the value of Keq at this temperature? Does the equilibrium favor reactants or products?

Answer 1

If you want Kp is it
Kp = (PCl5)/(PCl3)(Cl2)
Substitute and solve for Kp.

I assume Keq is Kc although I don't know that. You can convert Kp to Kc by
Kp = Kc(RT)^{delta n</sup)
where delta n = #n products- #n reactants = 1-2 = -1}