This article describes the accurate determination of the molar mass M of a sample of argon gas used for the determination of the Boltzmann constant. The method of one of the authors (Moldover et al 1988 J. Res. Natl. Bur. Stand.93 85-144) uses the ratio of the square speed of sound in the gas under analysis and in a reference sample of known molar mass. A sample of argon that was isotopically-enriched in 40Ar was used as the reference, whose unreactive impurities had been independently measured. The results for three gas samples are in good agreement with determinations by gravimetric mass spectrometry; (〈Macoustic/Mmass-spec〉 - 1) = (-0.31 ± 0.69) × 10-6, where the indicated uncertainty is one standard deviation that does not account for the uncertainties from the acoustic and mass-spectroscopy references.

中文翻译：

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通过高精度声学比较确定氩的摩尔质量

本文介绍了如何准确测定用于测定玻尔兹曼常数的氩气样品的摩尔质量 M。其中一位作者的方法 (Moldover et al 1988 J. Res. Natl. Bur. Stand.93 85-144) 使用被分析气体和已知摩尔质量的参考样品中声波的平方速度之比. 使用富含 40Ar 同位素的氩样品作为参考，其非反应性杂质已独立测量。三种气体样品的结果与重量质谱法测定结果非常吻合；(<Macoustic/Mmass-spec> - 1) = (-0.31 ± 0.69) × 10-6，其中指示的不确定度是一个标准偏差，不考虑来自声学和质谱参考的不确定度。