Question

Calculate the enthalpy of combustion (kj/mol) of ethyl stearate (c₂₀h₄₀o₂) an important component of many biodiesel fuels made from soybean oil and ethanol, given the following standard enthalpies of formation:

CO2(g) = -393.5 kJ/mol
H.O(l) = -285.8 kJ/mol
c₂₀h₄₀o₂(I) = -984.6 kJ/mol 7

Answer 1

The enthalpy of combustion of 1 mole of ethanol is -1366.1 kJ/mol.

Step-by-step explanation:

The enthalpy of combustion of 1 mole of ethanol can be calculated by using the enthalpies of formation of the products and reactants. The balanced equation for the combustion of ethanol is:

C₂H5OH(l) + 3O₂(g) → 2CO₂(g) + 3H₂O(l)

The enthalpy change for the combustion reaction can be calculated by using the enthalpies of formation of the products and subtracting the sum of the enthalpies of formation of the reactants. In this case, the enthalpy change is:

ΔH = (2ΔHf(CO₂) + 3ΔHf(H₂O)) - ΔHf(C₂H5OH)

Substituting the given values, the enthalpy of combustion of 1 mole of ethanol is:

ΔH = (2*(-393.5) + 3*(-285.8)) - (-278) kJ/mol

Simplifying this equation gives:

ΔH = -1366.1 kJ/mol