molar mass constant ; molar mass ; mole ; kilogram ; XRCD method ; enriched silicon
Zusammenfassung
After the revision of the International System of Units-the SI, the determination of the molar mass of an element or a compound is affected by the molar mass constant Mu and its associated uncertainty u(Mu). The variations and changes of the molar masses of silicon crystals highly enriched in 28Si used in the x-ray crystal density method for the realization and dissemination of the mole and the kilogram were investigated and a respective overview is given. All molar mass values M of a certain crystal agree within their uncertainties over the last years after the SI revision. The relative changes of M compared to Committee on Data for Science and Technology M(CODATA2014)with u(Mu) =0 gmol-1 are -3.5×10−10 (CODATA2018)and+1.05×10−9 (CODATA2022). The experimentally determined Mu is mainly dependent on the fine structure constant α. A theoretical impact of Mu and u(Mu) is simulated for a highly enriched silicon crystal according to the "Guide to the Expression of Uncertainty in Measurement". The simulation shows no significant change with the precondition of a similar development of α in the next years
CC BY 4.0 ; Creative Commons Attribution 4.0 License
Themenbereich der Metrologie
Metrologie in der Chemie und Stoffeigenschaften
Zitierung
Pramann, A., Borys, M., & Rienitz, O. (2026). Impact of the molar mass constant: the molar mass and its associated uncertainty. Metrologia, 63(2), 1–8. https://doi.org/10.1088/1681-7575/ae4c91
