The molar volume, symbol V_m, is the volume occupied by one mole of a substance (chemical element or chemical compound) at a given temperature and pressure. It is equal to the molar mass (M) divided by the mass density (ρ). It has the SI unit cubic metres per mole (m/mol), although it is more practical to use the units cubic decimetres per mole (dm/mol) for gases and cubic centimetres per mole (cm/mol) for liquids and solids.