Methanol is an important feedstock for producing synthetic fuels and chemicals. Two industrially viable syntheses are being compared at 298 K.
Process I: CO(g) + 2 H2(g) → CH3OH(l)
Process II: CO2(g) + 3 H2(g) → CH3OH(l) + H2O(l)
The following standard formation enthalpies are available.
Species ΔHf∘ (kJ·mol⁻¹)
CO(g) −110.5
CO2(g) −393.5
H2(g) 0.0
CH3OH(l) −238.7
H2O(l) −285.8
(a) Calculate ΔHrxn∘ for Process I.
(b) Calculate ΔHrxn∘ for Process II.
(c) Determine which process is more exothermic per mole of methanol produced. Support your answer with numerical evidence.
(d) Carbon-capture initiatives often favor Process II despite its enthalpy profile. Propose ONE environmental rationale for preferring Process II even if it is less exothermic, and briefly connect your reasoning to the balanced equations.