Phosphorus pentachloride decomposes at higher temperatures. PCl5(g) ⇄ PCl3(g) + Cl2(g) An equilibrium mixture at some temperature consists of 3.74 g PCl5, 208.23 g/mol 4.86 g PCl3, 137.33 g/mol 3.59 g Cl2, 70.91 g/mol in a 1.00-L flask. If you add 1.31 g of Cl2, how will the equilibrium be affected and what will the concentration of PCl5 be when equilibrium is reestablished? shift left shift right no shift will occur [PCl5] = mol/L