What is the Difference Between Enthalpy and Molar Enthalpy?

Enthalpy and molar enthalpy are both thermodynamic quantities used to describe the heat content of a system. The key difference between them lies in the context in which they are used:

• Enthalpy (H): It is the total heat content of a thermodynamic system. Enthalpy is a state function, meaning that it depends only on the current state of the system and not on the path taken to reach that state. The unit of measurement for enthalpy is joules or kilojoules.
• Molar Enthalpy: It is the enthalpy value given per mole of a substance. Molar enthalpy is an intensive property, as it divided the extensivity of the enthalpy by the number of moles of the substance. The unit of measurement for molar enthalpy is kilojoules per mole.

In summary, enthalpy represents the total heat content of a system, while molar enthalpy is the heat content per mole of a substance. Molar enthalpy is often used in experimental chemistry, as it can be measured and provides useful values on the energy that can be extracted from a substance.

Comparative Table: Enthalpy vs Molar Enthalpy

The difference between enthalpy and molar enthalpy can be summarized in the following table:

In summary, enthalpy represents the total heat content of a system, while molar enthalpy represents the total heat content per mole of reactant in the system. Enthalpy is an extensive property, meaning it depends on the amount of substance, whereas molar enthalpy is an intensive property, meaning it does not depend on the amount of substance.