Question

Calculate the enthalpy of combustion of butane (C4H10) in kJ/mol given that its heat of formation value is -126.6 kJ/mol and the heat of formation values of CO2 and H2O are -393.5 kJ/mol and -241.8 kJ/mol, respectively.

Answer 1

To calculate the enthalpy of combustion of butane  C4H10 , we can use the following equation:H_combustion =  H_f products  -  H_f reactants The balanced combustion reaction for butane is:C4H10 + 6.5 O2  4 CO2 + 5 H2ONow, we can plug in the given heat of formation values for each compound:H_combustion = [4 -393.5  + 5 -241.8 ] - [ -126.6  + 6.5 0 ]Note that the heat of formation for O2 is 0 kJ/mol since it is in its standard state.H_combustion = [-1574 +  -1209 ] - [-126.6]H_combustion = -2783 + 126.6H_combustion = -2656.4 kJ/molTherefore, the enthalpy of combustion of butane  C4H10  is -2656.4 kJ/mol.