[SOLVED] What am I doing wrong? Thermochemistry 1. Calculate the heat per mole of CO2 produced for octane. 2. I just balanced the equation and calculated the total heat produced. Subtracted the heat of water produced from it. Then took that and divided it by the number of moles. 2(C8H18) + 5O2====> 16CO2 + 18H20 3. My answer was -359.5 KJ/mol. But thats not one of the choices. So what did I do wrong?