Metrologia · 2015 · 61 citations · 58 references
Natural SciencesChemistryPhysicsAcousticsMolecular PhysicsSpectroscopyAcoustic MeasurementPhysical AcousticsAcoustic Gas ThermometryAcoustic MetrologyAcoustic Properties Of FluidsMolar Mass
We have determined the acoustic and microwave frequencies of a misaligned spherical resonator \nmaintained near the temperature of the triple point of water and filled with helium with carefully \ncharacterized molar mass M = (4.002 6032 ± 0.000 0015) g mol-1, with a relative standard uncertainty \nur(M) = 0.37×10-6. From these data and traceable thermometry we estimate the speed of sound in our \nsample of helium at TTPW = 273.16 K and zero pressure to be u0 \n2 = (945 710.45 ± 0.85) m2 s-2 and \ncorrespondingly deduce the value R = (8.314 4743 ± 0.000 0088) J mol-1 K-1 for the molar gas \nconstant. We estimate the value k = R/NA = (1.380 6508 ± 0.000 0015) × 10-23 J K-1 for the Boltzmann \nconstant using the currently accepted value of the Avogadro constant NA. These estimates of R and k, \nwith a relative standard uncertainty of 1.06 × 10-6, are 1.47 parts in 106 above the values recommended \nby CODATA in 2010.
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