(c) calculate the heat produced by combustion per liter of ethanol under constant pressure. Ethanol has a density of 0.789 g/mL.
Recall that, at constant pressure, the enthalpy change is the same as heat, so we're dealing with enthalpy changes here. For the combustion of ethanol, from the above reaction, we produce 1.235x103 kJ of heat from 1 mol ethanol. We use the molar mass to put this on a per gram basis, and use the density to find the volume (and convert to liters.) here goes:
so we produce 2.12x104 kJ per liter of ethanol (this is heat liberated - I just left off the negative sign from above.)
OK, the enthalpy change from above is -1.235x103 kJ for production of 2 mol CO2. Convert this to g CO2 to get the amount of heat released per g CO2 formed: