Question

Calculate the enthalpy of combustion of ethane (C2H6) using the following information: The enthalpy of formation of C2H6 is -84.7 kJ/mol, the enthalpy of formation of CO2 is -393.5 kJ/mol, and the enthalpy of formation of H2O is -241.8 kJ/mol.

Answer 1

To calculate the enthalpy of combustion of ethane  C2H6 , we need to use the following equation:H_combustion =  H_f products  -  H_f reactants The balanced combustion reaction for ethane is:C2H6 + 7/2 O2  2 CO2 + 3 H2ONow, we need to find the enthalpy of formation for each product and reactant:H_f C2H6  = -84.7 kJ/molH_f CO2  = -393.5 kJ/molH_f H2O  = -241.8 kJ/molH_f O2  = 0 kJ/mol  since O2 is in its standard state Now, we can plug these values into the equation:H_combustion = [2  H_f CO2  + 3  H_f H2O ] - [H_f C2H6  + 7/2  H_f O2 ]H_combustion = [2   -393.5  + 3   -241.8 ] - [-84.7 + 7/2  0]H_combustion = [-787 +  -725.4 ] - [-84.7]H_combustion = -1512.4 + 84.7H_combustion = -1427.7 kJ/molTherefore, the enthalpy of combustion of ethane  C2H6  is -1427.7 kJ/mol.