In chemistry and related fields, the molar volume, symbol V<sub>m</sub>, or <math>\tilde V</math> of a substance is the ratio of the volume (V) occupied by a substance to the amount of substance (n), usually at a given temperature and pressure. It is also equal to the molar mass (M) divided by the mass density (ρ):
<math display="block">V_{\text{m = \frac{V}{n} = \frac{M}{\rho}</math>
The molar volume has the SI unit of cubic metres per mole (m<sup>3</sup>/mol), The interest stems from that accurate measurements of the unit cell volume, atomic weight and mass density of a pure crystalline solid provide a direct determination of the Avogadro constant.
The CODATA recommended value for the molar volume of silicon is , with a relative standard uncertainty of
See also
- Specific volume
- Standard temperature and pressure#Molar volume of a gas