Standard enthalpy of reaction
（重定向自Enthalpy of Reaction）
The standard enthalpy of reaction (denoted ΔHr) is the enthalpy change that occurs in a system when one mole of matter is transformed by a chemical reaction under standard conditions.
For a generic chemical reaction
the standard enthalpy of reaction ΔHr is related to the standard enthalpy of formation ΔHf of the reactants and products by the following equation: