https://doi.org/10.1351/goldbook.12217
The equation for mass-average molar mass is \[M_{\rm{m}} \equiv M_{\rm{w}} = \sum\limits_{M} w_{M}M\]
The equation for mass-average molecular weight is \[M_{\rm{r,m}} \equiv {M_{\rm{r,w}}} = \sum\limits_{M_{\rm{r}}} w_{M_{\rm{r}}} M_{\rm{r}}\]
Notes:
- For definition of the symbols, see molar-mass average.
- Quantities mass-average molecular weight, mass-average relative molar mass, and mass-average relative molecular mass (\(M_{\rm{r,m}}\)) are synonyms. These quantities are dimensionless (pure numbers) and are not associated with any units.