1. The problem statement, all variables and given/known data What is the standard Gibbs free energy of formation of water vapor at 25 C if for the reaction shown below under standard conditions, ΔH = -484 kJ/mol and ΔS=-89 J/mol K? 2H2 + Os→2H2O 2. Relevant equations ΔG = ΔH-TΔS 3. The attempt at a solution Usually I can do these problems with no issue but I cannot seem to get the correct answer (which is -229 kJ/mol). First, I converted -89 J/mol K to kJ = 0.089 J/mol K. Plugging this into the equation gives me: ΔG = (-484 kJ/mol) - 298 K(-.089 kJ/mol K) = -457 kJ/mol. I did this problem twice, making sure my units were correct. Is my book wrong or did I do something wrong in the calculations? Thanks in advance.