Question

Calculate the enthalpy of formation of acetic acid., if it's enthalpy of combustion is 860 kj/mol

Answer 1

Hii dear,

# Given-

ΔH(combustion) = -860kJ/mol

ΔH(CO2) = -393.5kJ/mol

ΔH(H20) = -285.9kJ/mol

# Solution-

Combustion reaction occurs as follows,

C2H4O2 + 2O2 --> 2CO2 + 2H2O

Enthalpy of combustion is given by,

ΔH(combustion) = 2ΔH(CO2) + 2ΔH(H2O) -ΔH(C2H4O2)

ΔH(C2H4O2) = 2ΔH(CO2) + 2ΔH(H2O) - ΔH(combustion)

ΔH(C2H4O2) = 2×(-393.5) + 2×(-285.9) - (-860)

ΔH(C2H4O2) = -498.8 kJ/mol

# Enthalpy of formation of acetic acid is -498.8 kJ/mol.