The Thermodynamic Properties of Liquids ... - ACS Publications

trostatic differences result from changed lattice param- eters, while differences in WC and WBH include effects in short-range forces and vibrational ...
1 downloads 0 Views 518KB Size
THEENTROPY OF MIXING

IX 0.5

1255

A

.

T

?I

-

I

0

I

Electrostatic

Since extensive covalent bonding leads to large negative A’s,4 the present slight positive A’s substantiate the basic ionic nature of the alkali hydrides. This conclusion agrees with recent analysisz6of electrical conductive studies on molten LiH. The effect of isotopic substitution on alkali hydride cohesive energies is shown in Figure 1 where the percentage differences R between hydride and deuteride energies are given for Li, Na, and K salts. The electrostatic differencesresult from changed lattice parameters, while differences in WC and WBH include effects in short-range forces and vibrational energies. The

isotope effect is small (