Speed of sound of n-hexane and n-hexadecane at temperatures between 298 and 373 K and pressures up to 100 MPa

Measurements of the speed of Sound It for n-hexane and rr-hexadecane Lit te mperatures of 298.3, 323.15, 348.15, and 373.15 K and at pressures up to 10 0 MPa are reported. The speeds of sound, the temperatures, and the pressure s are subject to an uncertainty of +/-0.1%, +/-0.01 K, and +/-0.2 MPa, resp ectively. These measurements were undertaken using a nea apparatus which ha s been constructed for measurement of the speed of sound in liquids and sup ercritical fluids at pressures up to 200 MPa and at temperatures between 24 8 and 473 K. The technique is bused on a pulse-echo method with a single tr ansducer placed between two plane parallel reflectors. The speed of sound i s obtained fi om the difference between the round-trip transit times in the two paths. It is expected that both the precision and the accuracy of the method can be further improved.