Thermodynamic, Transport, and Chemical Properties of “Reference ...

w / m·s -114001350MethylcyclohexanePropylcyclohexane1300125012001150110010501000270 280 290 300 310 320 330 340 350T / KFigure 13: Measured speed of sound data for methyl- and propylcyclohexaneAdiabatic compressibilities at ambient pressure were obtained from the measureddensities and speeds of sound via the thermodynamic relation κ s = -(∂V/∂p) s /V = 1 / (ρw 2 ),where V denotes volume, p is pressure, is the density, and w the speed of sound.Subscript s indicates “at constant entropy s.” For convenience, the calculated adiabaticcompressibilities are included in Table 11.The speed of sound and adiabatic compressibility data of the two liquids at ambientpressure are plotted in Figure 14 as a function of temperature. Comparing the plotsillustrates how changing the molecular structure of methylcyclohexane by adding anethyl-group -CH 2 -CH 2 - to the aliphatic side chain to form propylcyclohexane influencesthe macroscopic properties of the two compounds. The speed of sound increases between29