What does Hess's law state? O If the heat energy of a reaction increases, the enthalpy of the reaction decreases proportionally. O If a reaction takes place in several steps, then its enthalpy is the difference between the enthalpies of the intermediate reactions. The enthalpy change of the overall process is the sum of the enthalpy changes of its individual steps and does not depend on the route taken. O The enthalpy change of an overall process cannot be determined from the enthalpy of its individual steps