HESS'S LAW (LAW OF CONSTANT HEAT SUMMATION; HESS'S LAW OF HEAT SUMMATION)

The heat released or absorbed by a process is the same no matter how many steps the process takes. For example, given a reaction A B, Hess's law says that H for the reaction is the same whether the reaction is written as A C B or as A B. This is the same as writing that H(A B) = H(A C) + H(C B).