What is the heat of combustion of ethane, C2H6, in kilojoules per mole of ethane? Enthalpy of formation values can be found in this list of thermodynamic properties.

Answer 1

You didn't give us the enthalpy of formation values that are found in the list of thermodynamic properties. I could look them up, but so could you. Here is how to do the problem once you look up those values.

Write the balanced equation for combustion of C2H6:

2C2H6(g) + 7O2(g) ==> 4CO2(g) + 6H2O(g) ... balanced equation

Look up ∆Hformation for CO2(g) and H2O(g) and multiply the value for CO2 by 4 and that for H2O by 6. Add these values to get ∆Hproducts

Look up ∆Hformation for C2H6 and multiply by 2. The ∆H for O2 is zero. Add these values to get ∆H reactants.

Calculate ∆Hproducts - ∆Hreactants and that will be your answer