12219 IUPAC Gold Book - (z + 1)-average molar mass 10.1351/goldbook.12219 12219 current mentioned: (z + 1)-average molecular weight, (z + 1)-average relative molar mass, (z + 1)-average relative molecular mass, $M_{\rm{r,z+1}}$ 1 The equation for (z + 1)-average molar mass is \[M_{\rm{z+1}} = \frac{\sum\limits_{M} w_{M}M^{3}}{\sum\limits_M w_{M}M^{2}}\] The equation for (z + 1)-average molecular weight is \[M_{\rm{r,z+1}} = \frac{\sum\limits_{M_{\rm{r}}} w_{M_{\rm{r}}}M^{3}}{\sum\limits_{M_{\rm{r}}} w_{M_{\rm{r}}}M^{2}}\] For definition of the symbols, see molar-mass average. Quantities (z + 1)-average molecular weight, (z + 1)-average relative molar mass, and (z + 1)-average relative molecular mass (\(M_{\rm{r,z+1}}\)) are synonyms. These quantities are dimensionless (pure numbers) and are not associated with any units. molar-mass average https://goldbook.iupac.org//terms/view/12215 PAC, 2015, 87, 71. 'Definitions of terms relating to individual macromolecules, macromolecular assemblies, polymer solutions, and amorphous bulk polymers (IUPAC Recommendations 2014)' on page 84 (https://doi.org/10.1515/pac-2013-0201) https://goldbook.iupac.org/terms/view/12219/html https://goldbook.iupac.org/terms/view/12219/json https://goldbook.iupac.org/terms/view/12219/plain Citation: '(z + 1)-average molar mass' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. 10.1351/goldbook.12219 The IUPAC Gold Book is licensed under Creative Commons Attribution-ShareAlike CC BY-SA 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/) for individual terms. If you are interested in licensing the Gold Book for commercial use, please contact the IUPAC Executive Director at executivedirector@iupac.org . The International Union of Pure and Applied Chemistry (IUPAC) is continuously reviewing and, where needed, updating terms in the Compendium of Chemical Terminology (the IUPAC Gold Book). Users of these terms are encouraged to include the version of a term with its use and to check regularly for updates to term definitions that you are using. 2026-04-18T10:07:08+00:00