Molar, mass and volume quantities
Thermodynamic constants

A thermodynamic property is related to a quantity of matter, which is either the mole, the unit of mass or the unit of volume.

• Remember that the molar mass of a substance M is the mass, expressed in grams, of 6.022 05 × 10²³ molecules (Avogadro's number, N = 6.022 05 × 10²³ mol ^–1).

  Example

  normal heptane has a molar mass M = 100. This means 100 g · mol ^–1 or 100 × 10^–3 = 0.1 kg · mol ^–1 (or 100 kg · kmol ^–1).

• Knowing the value of any molar quantity A (in SI units · mol ^–1), it is straightforward to calculate the mass quantitya (in SI units · kg ^–1) by a = A /M (where M is expressed in kg · mol ^–1).

  Example

  the molar...