For 10 points, name this law which states that adding the change in enthalpy of each step of a reaction yields the total change in enthalpy for the reaction.
This law is used to determine entropy and free energy in the Bordwell thermodynamic cycle. As a consequence of this law, one can calculate lattice energy in the Born-Haber cycle. This law works because the quantity it concerns is the sum of internal energy and quantity pressure times volume and is thus a state function. As a result, this law allows for addition of the changes in that quantity for a series of stepwise reactions to determine the overall change in that quantity. For 10 points, name this law which states that adding the change in enthalpy of each step of a reaction yields the total change in enthalpy for the reaction.
This law is used to determine entropy and free energy in the Bordwell thermodynamic cycle.
{Hess's} law [accept {law} of {heat summation} or {enthalpy summation} until mentioned]