The density and molar volumes of ternary alloys of cross sections of the sodium-potassium-cesium system technically important temperatures

The density of well over $130$ liquid ternary alloys of the $\text{Na}$–$\text{K}$–$\text{Cs}$ system along the cross sections extending towards the vertexes of potassium, cesium, and sodium of the triangle of compositions is determined experimentally and by a numerical-and-graphic method. The pycnometric method is used for measuring the density in the temperature range from liquidus temperature to $553$ K. The relative experimental error is $0.10\%$ at confidence probability of $95\%$. The polytherms of density and molar volumes of the alloys are described by linear equations. In so doing, the isotherms of density of cesium-“rich” ternary alloys exhibit positive deviations, and the isotherms of molar volumes exhibit minor negative deviations from additivity, which are indicative of the nonideality of the solutions of the $\text{Na}$–$\text{K}$–$\text{Cs}$ system.