1.   It is therefore normal to quote the standard molar enthalpy change for a process.

2.   The standard molar enthalpy of a reaction is the enthalpy change under standard conditions per mole of the reaction as specified by a balanced chemical equation.

3.   We should thus avoid using phrases such as the standard molar enthalpy of oxidation of hydrogen as they are ambiguous.

4.   The standard molar enthalpy of formation could have two different values depending on how we write the equation.

5.   Thus, the standard molar enthalpy of formation.

6.   The standard molar enthalpy of formation of a compound or ion is a measure of its stability relative to its constituent elements.

7.   For example, the standard molar enthalpy of combustion of propane is per mole of propane.

8.   The standard molar enthalpy of fusion, is the enthalpy change that accompanies the fusion of one mole of a substance at its melting point at one atmosphere pressure.

9.   The standard molar enthalpy of vaporisation, is the enthalpy change that accompanies the vaporisation of one mole of a substance at its boiling point at one atmosphere pressure.

10.   We have already noted that the value for the molar enthalpy of vaporisation of water is anomalously high.