Ethanol, C₂H₅OH, is being promoted as a clean fuel and is used as an additive in many gasoline mixtures. Calculate the ΔH°_rxn for the combustion of ethanol. (ΔH°_f [C₂H₅OH(l)] = -277.7 kJ/mol; ΔH°_f [CO₂(g)] = -393.5 kJ/mol; ΔH°_f [H2O(g)] = -241.8 kJ/mol)

Question

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The correct answer is A because the ΔH°_rxn for the combustion of ethanol is -1234.7 kJ. This can be calculated using the following equation:ΔH°_rxn = ΣΔH°_f (products) - ΣΔH°_f (reactants)ΔH°_rxn = [ΔH°_f (CO₂(g)) + ΔH°_f (H2O(g))] - [ΔH°_f (C₂H₅OH(l))]ΔH°_rxn = [(-393.5 kJ/mol) + (-241.8 kJ/mol)] - (-277.7 kJ/mol)ΔH°_rxn = -1234.7 kJ

Ethanol, C2H5OH, Is Being Promoted as a Clean Fuel and Is

Ethanol, C₂H₅OH, Is Being Promoted as a Clean Fuel and Is