The table in the back of my wife’s chemistry textbook tabulates values of the standard enthalpy of formation delta-Hf0, the standard entropy S0, and the standard free energy of formation delta-Gf0, for a wide variety of elements and compounds, all evaluated at 25C. As I understand it, they should be connected by the relationship
delta-Gf0 = delta-Hf0 – T*S0
They aren’t. For instance, for liquid water, it gave
delta-Hf0 = -286 kJ/mole
S0 = 69.96 J/(mole K)
delta-Gf0 = -237.2 kJ/mole
25C corresponds to T = 298.16 K , so by my calculations detla-Gf0 should be
-286 kJ/mole – 298.16 K * (69.96 J/(mole K) / 1000 (kJ/J)) = -307 kJ/mole
None of the entries in the table work out as I expected, which rules out a typo. I’ve checked with other sources, and they all agree tolerably well with the values tabulated in this textbook. What am I misunderstanding?