Chapter 15, Problem 85E

The system described by the reaction:
$\text{CO}\left(\text{g}\right)+\text{Cl}\left(\text{g}\right)\rightleftharpoons {\text{COCl}}_{\text{2}}\left(\text{g}\right)$ is at equilibrium at a given temperature when
P_CO = 0.30 atm,
${\text{P}}_{{\text{Cl}}_{\text{2}}}$ = 0.10 atm, and
${\text{P}}_{{\text{COCl}}_{\text{2}}}$ = 0.60 atm. Pressure of
Cl₂(g) = 0.40 atm is added. Find the pressure of CO when the system returns to equilibrium.