Answer:
B. PE of products – PE of reactants
Step-by-step explanation:
The enthalpy, H, reference to the amount of energy that a thermodynamic system exchanges with its environment, that is, the amount of energy that the system absorbs or releases. Its difference is calculated between the final and initial states of the system, so in a chemical reaction the final state is the one of the products and the initial state is the one of the reactants. By convention, this kind of difference are always the final state minus the initial state.