# Molecular Weight

Written by Jerry Ratzlaff on . Posted in Thermodynamics

Molecular weight, abbreviated as MW, also called molecular mass, abbreviated as Mr, refers to the average mass of one molecule of a substance, 1⁄12 (0.083) the mass of carbon 12 atom.

### Molecular weight formula

$$\large{ MW = \frac{ R^* }{ R } }$$

Where:

$$\large{ MW }$$ = molecular weight

$$\large{ R }$$ = specific gas constant

$$\large{ R^* }$$ = universal gas constant ( 8314 J/kmol-K )