Ethanol,C₂H₅OH,is promoted as a clean fuel and is used as an additive in many gasoline mixtures.Calculate the ΔH°_rxn for the combustion of ethanol. Substance ΔH°_f(kJ/mol)
C₂H₅OH(l) -277.0
CO₂(g) -393.5
H₂O(g) -241.8

Question

Quizplus · Accepted Answer

The correct answer is A because the ΔH°_rxn for the combustion of ethanol is -1235.4 kJ. This can be calculated using the following equation:ΔH°_rxn = ΣΔH°_f(products) - ΣΔH°_f(reactants)ΔH°_rxn = [ΔH°_f(CO₂) + ΔH°_f(H₂O)] - [ΔH°_f(C₂H₅OH)]ΔH°_rxn = [(-393.5 kJ/mol) + (-241.8 kJ/mol)] - (-277.0 kJ/mol)ΔH°_rxn = -1235.4 kJ

Ethanol,C2H5OH,is Promoted as a Clean Fuel and Is Used as an Additive

Ethanol,C₂H₅OH,is Promoted as a Clean Fuel and Is Used as an Additive