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

Question

Ethanol, C₂H₅OH, is being promoted as a clean fuel and is used as an additive in many gasoline mixtures. Calculate the

\Delta

H°_rxn for the combustion of ethanol.
(

\Delta

H°_f [C₂H₅OH(l) ] = -277.7 kJ/mol;

\Delta

H°_f [CO₂(g) ] = -393.5 kJ/mol;

\Delta

H°_f [H₂O(g) ] = -241.8 kJ/mol)

Quizplus · Accepted Answer

The balanced combustion reaction for ethanol is: C2H5OH(l) + 3O2(g) → 2CO2(g) + 3H2O(g). Using the standard enthalpies of formation, ΔH°rxn = [2(-393.5) + 3(-241.8)] - [-277.7] = -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