Final answer:
The ΔH rxn for the combustion of ethanol to produce acetic acid and water is calculated as -492.6 kJ/mol using the given enthalpies of formation.
Step-by-step explanation:
To calculate the ΔH rxn for the combustion of ethanol (C₂H₅OH(l)), we need to know the enthalpies of formation for the reactants and products. The balanced chemical equation for the combustion of ethanol to form acetic acid (CH₃CO₂H(l)) and water (H₂O(l)) is:
C₂H₅OH(l) + O₂(g) → CH₃CO₂H(l) + H₂O(l)
Next, we apply the formula for the enthalpy change of the reaction (ΔH rxn):
ΔH rxn = ∑ (ΔH°f products) - ∑ (ΔH°f reactants)
Given the enthalpies of formation:
C₂H₅OH(l): -277.7 kJ/mol
CH₃CO₂H(l): -484.5 kJ/mol
H₂O(l): -285.8 kJ/mol
Assuming complete combustion, we have:
ΔH rxn = [(-484.5) + (-285.8)] - [(-277.7)]
ΔH rxn = -770.3 - (-277.7)
ΔH rxn = -770.3 + 277.7
ΔH rxn = -492.6 kJ/mol
The heat of combustion of ethanol in this reaction is -492.6 kJ/mol.