What are the equilibrium partial pressures of PCl3
**,** Cl2, and PCl5, respectively?
**Express your answers numerically in atmospheres with
three digits after the decimal point, separated by
commas.**
� An Equilibrium Study: Phosphorus Trichloride/Phosphorus
Pentachloride Equilibrium
For the exothermic reaction
PCl3(g)+Cl2(g)?PCl5(g)
*K*p = 0.180 at a certain temperature.
A flask is charged with 0.500 atm PCl3 **,** 0.500
atm Cl2, and 0.300atm PCl5 at this temperature.

## Answer

For the reaction: Pci, (g) + Cl2 (g)–PCIs (g) Initial partial pressures are Pc 0.300 atm The equilibrium constant, K for the reaction is 0.140 Calculate reaction quotient, as PCl, 0.300 0.500 > Kp (0.180 So, reaction shifts towards reactants to attain equilibrium Construct ICE table and obtain their equilibrium partial pressures PCI,(s)+Cl,()PC,() 0.300 I(atm): 0.500 C(atm): +x E(atm) :0.500+x 0.500+x 0.300-x Equilibrium constant, 0.500 PCl, 0.300 – x 0.180-_ (0.500+x) x = 0 .209 So, equilibrium partial pressures are calculated as follows %, = A = (0.500 + x)-0.500 + 0.209-0.709 atm Roc,-( 0.300-x) = 0.300-0.209 = 0.091 atm