The enthalpy change per mole of a substance and is measured in J/mol or kJ/mol. This quantity is called what?

• A. Enthalpy
• B. Molar Enthalpy
• C. Specific Heat
• D. Internal Energy

Answer: (B)

Molar enthalpy is the energy change per mole of substance, and it’s written in units like J/mol or kJ/mol. This means you take the total enthalpy change for whatever amount you have and divide by how many moles are involved, giving a per-mole value you can compare across reactions or substances. If you were talking about enthalpy itself without reference to amount, the units would be J or kJ, not J/mol. Specific heat refers to energy required to raise the temperature of a given mass, so its units are J/(kg·K) (or J/(g·K)), not per mole. Internal energy is the energy contained in the system, measured in joules, and the per-mole form isn’t the standard way it’s described here.