Third Method

[JennyZhu1K]

I understand how to use the standard enthalpies of formation to figure out the net enthalpy of a reaction, but could somebody explain, conceptually, why this works?

[Gianna Greco 1G]

Standard enthalpy is the change in enthalpy for a reaction, and we calculate it using the standard enthalpies of formation for each of the reactants and products. This works because if we add all the enthalpies of formation, we will end up with the net change in enthalpy, which is our standard enthalpy.