Molar volume

The molar volume or molar volume (symbol: V m ) of a substance indicates which volume occupied by a mole of this substance. Its SI unit is m3/mol.

It arises from the quotient of the volume V and the amount of substance n, and can be made of the molar mass M and the density ρ of the corresponding substance can be calculated.

It describes the volume which a total of 6.022 · 1023 particles ( Avogadro's number ) is filled in a substance. It is the molar volume of a molar and thus intensive magnitude, while the volume itself is an extensive quantity.

For solids and liquids the molar volume depends on the particular material from ( material property ).

Molar volume of an ideal gas

Rearranging the ideal gas equation is obtained for the molar volume of an ideal gas:

With

• R is the universal gas constant
• T is the temperature, and
• P is the pressure.

The molar volume of an ideal gas is thus under current measurement accuracy ( regardless of which gas is present in detail ):

In the German standard DIN 1343, issued January 1990, the molar standard volume of an ideal gas is not provided with the older value of ( 22.414 ± 0.000 10 19) l / mol. The older value covers the younger entirely due to the increased uncertainty.

For real gases, the figures available from the ideal gas law are only approximate, even for low pressures and not too low temperatures.