Ethanol can be prepared in several ways. It can be produced during alcohol fermentation (Reaction A). It is also produced commercially from ethylene (Reaction B). Calculate the ΔG°_rxn (kJ•mol^–1) of each reaction.

A. C₆H₁₂O₆(s) → 2 C₂H₅OH(l) + 2 CO₂(g)

B. C₂H₄(g) + H₂O(g) → C₂H₅OH(l)

Determine which method requires less energy under standard conditions.

Substance            ΔG°_f (kJ/mol)
C₆H₁₂O₆(s)           –910.4
C₂H₄(g)                   68.4
C₂H₅OH(l)           –174.8
H₂O(g)                 –228.6
CO₂(g)                 –394.4