Phosphorous and chlorine gases combine to produce phosphorous trichloride:P2(g) + 3Cl2(g) ⇌ 2PCl3(g)ΔG° at 298 K for this reaction is −642.9 kJ. The value of ΔG at 298 K for a reaction mixture that consists of 1.500 atm P2, 1.600 atm Cl2 and 0.650 atm PCl3 is __________.