12221 IUPAC Gold Book - apparent molar mass 10.1351/goldbook.12221 12221 current mentioned: $M_{\rm{r,app}}$, apparent molecular weight, apparent relative molar mass, apparent relative molecular mass 1 Molar mass, molecular weight, relative molar mass, or relative molecular mass calculated from experimental data without the application of appropriate corrections. Quantities apparent molecular weight, apparent relative molar mass, and apparent relative molecular mass (\(M_{\rm{r,app}}\)) are synonyms. These quantities are dimensionless (pure numbers) and are not associated with any units. Examples of corrections are those for finite polymer concentration, association, preferential sorption, compositional heterogeneity, constitutional heterogeneity, and also from experimental data obtained from an instrument (often an SEC instrument) calibrated using standard samples of known molar masses of a polymer constitutionally different from that being analysed. Molar mass https://goldbook.iupac.org//terms/view/12214 PAC, 2015, 87, 71. 'Definitions of terms relating to individual macromolecules, macromolecular assemblies, polymer solutions, and amorphous bulk polymers (IUPAC Recommendations 2014)' on page 85 (https://doi.org/10.1515/pac-2013-0201) https://goldbook.iupac.org/terms/view/12221/html https://goldbook.iupac.org/terms/view/12221/json https://goldbook.iupac.org/terms/view/12221/plain Citation: 'apparent 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.12221 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. 2026-06-13T16:04:59+00:00