Excess molar volumes of (propiophenone + toluene) and estimated density of liquid propiophenone below its melting temperature

The densities of liquid propiophenone and toluene, and of their mixtures were measured at six temperatures between 283.15 K, and 328.15 K by means of a vibrating-tube densimeter. The excess molar volumes VmE calculated from the density data show that the deviations from ideal behaviour in the systems studied (all being negative) become more negative as the temperature is raised. The VmE results were correlated using the fourth-order Redlich–Kister equation, with the maximum likelihood principle being applied for the determination of the adjustable parameters. The density values of liquid propiophenone at 283.15 K and 288.15 K (below its melting temperature equal 291.76 K) needed for the computation of VmE were determined both from the extrapolation of densities measured at higher temperatures and from excess volume correlation using the respective density value as an adjustable parameter. Both the estimation methods are compared and discussed.