Pressure and temperature dependence of the speed of sound and related properties in normal octadecane and nonadecane

The speed of sound was mesured in liquid n-octadecane and n-nonadecane using a pulse technique operating at 3 MHz. The measurements were carried out at pressures up to 150 M Pa in the temperature range from 313 to 383 K. The experimental results combined with atmospheric density measurements were then used to evaluate volumetric properties such as the density and the isentropic and isothermal compressibilities up to 150 M Pa in the same range of temperature. The density data were fitted with a six-parameter modified Tait equation within the experimental uncertainty.