Standard heat enthalpy of a compound is equal to its:

Explanation

The enthalpy of reaction for any chemical reaction is equal to the difference between the sum of the enthalpies of the formation of the products and the sum of the enthalpies of the reactants. In an exothermic reaction, the heat content or enthalpy of the product H2 is less than that of the reactants H1. Since the system has lost heat, we can say the enthalpy change for the reaction ∆H is negative, In an endothermic reaction, the enthalpy of product H2 is greater than that of the reactants H1, and the enthalpy change, ∆H is positive. The standard enthalpy of a reaction ∆Ho is the enthalpy change that occurs when a certain number of moles of reactants as indicated by the balanced chemical equation, react together completely to give the products under standard conditions, i.e 25 °C (298K) and one atmosphere pressure. All the reactants and products must be in their standard physical states. Its units are kJ mol-1 .