Molar Volume of Molten Binary CaCl₂-NaCl, LaCl₃-NaCl, and LaCl₃-CaCl₂ and Ternary LaCl₃-CaCl₂-NaCl Systems

Abstract

Molar volumes of molten CaCF-NaCl, LaCl 3 -NaCl, LaCl 3 -CaCl 2 and the quasi-binary systems LaCl 3 -/7NaCl • mCaCl 2 (mole ratio n:m= 1:3.2, 1:1, and 2.6:1) have been measured by the dilatometric method, and expressed as functions of both temperature and mole fraction by means of least squares regression. The molar volumes of molten LaCl 3 -NaCl and LaCl 3 -CaCl 2 showed positive and negative deviations, respectively, from additivity, while CaCl 2 -NaCl and the three quasi-binary systems satisfied approximately the additivity. The isotherm of molar volume for ternary LaCl 3 -CaCl 2 -NaCl system at 900 °C was represented according to the isotherms of three binary and three quasi-binary systems.

Surface Tensions of Molten Binary CaCl2-NaCl, LaCl3-NaCl, and LaCl3-CaCl2 and Ternary LaCl3-CaCI2-NaCl Systems

“…Reprint requests to Prof. J. M ochinaga, D epartm ent of Synthetic Chemistry, Faculty o f Engineering, Chiba University, Chiba-shi, C hiba 260, Japan. crystal were determined by emission spectroscopy, the result being almost the same as reported in [2 ], The chemicals NaCl and CaCl2 were of analytical reagent grade. They were dried under vacuum of 10~3Torr by heating 50 °C below their melting points for 8 hours and then melted.…”

“…The calculated results for the binary systems are given in Fig. 5 together with the composition dependence of the excess molar volumes obtained in [2], Evidently, these show an opposite composition dependence. AEs/a of LaCl3-NaCl, with its positive excess molar volume, its maximum being at 30 mole% LaCl3, has a large negative value at the same concentration.…”

“…where 2r is the inside diameter of the capillary, g the acceleration of gravity, h the height of manometer column, rf, the density of di-n-butyl phthalate, d2 the density of the melt, which was obtained from the molar volume data [2 ], i the depth of the immersion of the capillary into the melt.…”

“…Molten binary and ternary mixtures of LaCl3, CaCl2, and NaCl are interesting because the cations La3+ (1.045 A), Ca2+ (1.00 A), and N a+ (1.02 A) have different charge but nearly equal ionic radii [1]. In a previous study on molten CaCl2-NaCl, LaCl3-NaCl, LaCl3-CaCl2 and LaCl3-CaCl2-NaCl [2] it was found that the molar volumes of molten LaCl3-NaCl and LaCl3-CaCl2 show positive and negative deviations from additivity, respectively, while those of CaCl2-NaCl and the quasi-binary LaCl3-nNaCl.mCaCl2 (n:m = mole ratio) are ap proximately additive. It is of much interest to see if these bulk property are reflected in the surface tension.…”