Which of the following is completely true about the relationship between ΔG and T for this reaction?

Question

For the reaction, Fe₂O₃ (s) + 3 H₂(g) <=> 2 Fe(s) + 3 H₂O(g), ΔG° = 53 kJ at 25 °C and ΔH° = 100 kJ. 

The answer is ΔG < 0 when T > 635 K, but I would like to know why this is true?

Answer 1

Hi Elva V.,

Set up your standard .delta.G = .delta.H - T.delta.S equation, and solve for the given data to find .delta.S . When you set .delta.G = 0 and solve for T, that tells you the "break-even" temperature to drive the reaction using the entropy term.

-- Cheers, --Mr. d.