Density and adiabatic compressibility of $\rm LiF + KBr$ mixtures in the two-phase region

In this paper, we experimentally studied the adiabatic compressibility $\beta$ of an exfoliating liquid mixture, $\rm LiF + KBr$, on the saturation line in a temperature range from the melting point to the critical mixing temperature using the sound velocity $u$ measured by the pulse method and the density $\rho$ determined by hydrostatic weighing based on the ratio $\beta = u^{-2}\rho^{-1}$.The coefficients of the temperature dependences of the compressibility and density of the upper and lower equilibrium phases are shown to have opposite signs due to the superposition of the thermal motion of ions and changes in the phase composition. The reduced differences $\beta^*$ and $\rho^*$ for the contacting phases decrease with decreasing reduced temperature $T^*$ in accordance with the empirical exponential equations $\beta^* \approx T^{*1.017}$ and $\rho^* \approx T^{*0.494}$.