Measurements of the speed of sound in liquid and supercritical ethane

Comprehensive and accurate measurements of the speed of sound in pure ethane have been carried out in the liquid and supercritical regions by a double-path-length pulse-echo technique. The measured data cover the temperature range from 240 K to 420 K with pressures up to 100 MPa. The expanded measurement uncertainties at the 95% confidence level amount to 2.1 mK for temperature, 0.007% for pressure, and 0.01% for speed of sound with the exception of a few state points in the vicinity of the critical point, where the uncertainty increases up to 0.016%. The quality of the measurements is demonstrated by comparisons with literature data and the fundamental equation of state for ethane by D. Bücker and W. Wagner [J. Phys. Chem. Ref. Data 35 (2006) 205–266].