Two separate combustion reactions are considered under standard conditions (298 K, 1 bar):
Reaction 1: 2 CO(g) + O₂(g) → 2 CO₂(g)
Reaction 2: 2 H₂(g) + O₂(g) → 2 H₂O(l)
Selected standard Gibbs free energies of formation, ΔGf∘, are provided.
Species (state) ΔGf∘ (kJ mol⁻¹)
CO(g) −137
CO₂(g) −394
H₂(g) 0
H₂O(l) −237
O₂(g) 0
Use the data to analyze the thermodynamic favorability of the two reactions.
(1) For each reaction, predict whether ΔGrxn∘ is negative, zero, or positive. Support your prediction with qualitative reasoning that references the numerical data but does not require carrying out full arithmetic subtraction.
(2) Between Reaction 1 and Reaction 2, determine which is expected to release the greater amount of free energy per mole of O₂ consumed. Justify your answer by comparing the relative magnitudes of the driving forces apparent in the tabulated values.