Hess's law applied to combustion enthalpy

Steps:

• Balance the equation: C₂H₅OH(l) + 3O₂(g) → 2CO₂(g) + 3H₂O(l).
• Use ΔH°_comb = [2ΔH°_f(CO₂) + 3ΔH°_f(H₂O)] - ΔH°_f(C₂H₅OH).
• Compute products: 2(-394) + 3(-286) = -788 - 858 = -1646 kJ mol⁻¹.
• Subtract reactants: -1646 - (-277) = -1369 kJ mol⁻¹.

Why B is correct:

• Not enough information; calculated value (-1369 kJ mol⁻¹) does not match any option.

Why the others are wrong:

• A is too small, ignoring multiple product molecules.
• C approximates wrong balancing (1 CO₂ + 3 H₂O).
• D approximates unbalanced reaction (1 CO₂ + 1 H₂O).

Final answer: Not enough information.