Determination of the molar mass of argon from a high precision acoustic comparison

Published: May 18, 2017


XiaoJuan Feng, Jintao Zhang, Michael R. Moldover, Inseok Yang, Mark Plimmer, H. Lin


This article describes the accurate determination of the molar mass of a sample of argon gas used for a determination of the Boltzmann constant. The method due to one of the authors [Moldover et al., J. Res. Natl. Bur. Stand. 93, 85-144 (1988)] uses the ratio of the square speed of sound in the gas under analysis and in a reference sample of known molar mass. The results are in good agreement with determinations by gravimetric mass spectrometry, that the fractional difference arising from the two independent procedures is bounded within 0.37×10-6 for the argon sampling from the same container. The uncertainties with both procedures are consistent.
Citation: Metrologia
Volume: 54
Issue: 3
Pub Type: Journals

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acoustic thermometry, speed of sound, Boltzmann Constant, Argon, Argon Isotopes
Created May 18, 2017, Updated November 01, 2017