If the amount of substance in moles can be determined, then each of these thermodynamic properties may be expressed on a molar basis, and their name may be qualified with the adjective " molar", yielding terms such as molar volume, molar internal energy, molar enthalpy, and molar entropy. The symbol for molar quantities may be indicated by adding a subscript "m" to the corresponding extensive property. For example, molar enthalpy is formula_29. Molar Gibbs free energy is commonly referred to as chemical potential, symbolized by formula_30, particularly when discussing a partial molar Gibbs free energy formula_31 for a component formula_32 in a mixture.