LiH-LiCl

Most important lithium compounds LijCO, LiOH, LiH, LiCl... 

However, data concerning the solubility of LiH in LiCl/KCl mixtures is scarce. No data is available except the LiH solubility in the LiCl-KCl eutectic for a given temperature [12]. The binary LiH-LiCl phase diagram was experimentally investigated and calculated by Johnson et al. [13-15] whereas the KCl-LiH and LiH-LiCl-KCl systems have not yet been investigated. The aim of this work is to determine the solubility of lithium hydride in LiCl/KCl mixtures by thermal analysis in order to optimise the melt composition for the... 

For the LiH-LiCl mixtures, three compositions were investigated. The eutectic temperature was determined from the average value of three measurements. The eutectic temperature of the LiH-LiCl system was found close to 487 3 °C, which agrees with the data from Barber and Sloan [20], who obtained 486 °C but it is slightly lower than the value of 495 C provided by Johnson et al. [13]. A larger difference was observed with the data published by P. Ehrlich and W. Deissmann [21], who measured the eutectic temperature of the LiH-LiCl system to be close to 450 C. 

The ternary LiH-LiCl-KCl exhibits one eutectic composition with a melting point of 341 3 °C for a composition close to 10-60-30 at%. 

The liquidus curve was determined for the whole composition range of the ternary LiH-LiCl-KCl system. 

Table 18.8 LiH and LiCl atom charges HF/6-311G calculations...

It is prepared by the gradual addition of aluminium chloride to a slurry of lithium hydride in ether. The precipitated LiCl and unreacted LiH are fdtered off. 

W7. Nernst has suggested that the hydrogen in lithium hydride plays the part of a halogen, and likens the reaction LiOH + H2=H20 +LiH with LiOH+HCl =H20+LiCl he shows similarities between lithium hydride and chloride in their crystalline form, at. vol., at. lit., heat of formation, coloration of ultra-violet rays, etc. The electrolysis of molten lithium hydride is also analogous with that of fused lithium chloride. Since lithium hydride is completely hydrolyzed in aq. soln., it is assumed that hydrogen acts as a very weak acid. 

TAS° at 298 K is +3 kJ mol-1. In the case of LiH, an ionic solid having the NaCl structure, a thermochemical analysis (see Chapter 5) can rationalise its thermodynamic stability relative to the elemental substances. However, AG for LiH is much less negative than for LiF or LiCl (—616... 

According to Dulong and Petit s rule the specific heat per gramatom amounts to about 6 cal./deg. Since now the specific heat per grammol. is 11.9 cal./deg. for NaCl at o° C, it follows that there must be two particles per molecule of NaCl. The specific heat depends, however, on the temperature, and deviations from this rule, both upwards and downwards, are numerous so that the argument is not so significant. For LiCl, LiH and MgO at o° C one finds 9.7, 7.8 and 8.4 cal./deg., respectively, for the molecular heat nevertheless these are also ionic lattices. 

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