Estimate the value of deltaGf for COCl2(l) at 25 degrees celcius
Using Standard Heats of Formation and Standard Entropy values at 25C apply to free energy equation => ∆G(f) = ∆H(f) - T∆S
∆H(f) = -220.1 Kj/mole (direct from thermo properties table)
∆S = -47.34 KJ/mole-K (from Hess's Law)*
T = 298K
*=> C + 1/2(O2) + Cl2 => COCl2
fm thermo properties table:
So(C) = 5.74 J/mol-K
So(O2) = 205 J/mol-K
So(Cl2) = 283.9 j/mol-K
∆S = ∑So(products) - ∑So(reactants) = [(283.9j/mol-k)] - [(223j/mol-K)+1/2(205j/mol-K)+(5.74j/mol-K)] = -47.34 j/mol-K
∆G(f) = (-220.1Kj/mole) - 298K(-47.34Kj/mole-K) = -205.9 Kj/mole