The Need to Pour Empty Space into a Fused Salt

The Need to Pour Empty Space into a Fused Salt 

There is another important fact about the melting process. When many ion lattices are melted, there is a 10 to 25% increase in the volume of the system (Table 5.10). This volume increase is of fundamental importance to someone who wishes to conceptualize models for ionic liquids because one is faced with an apparent contradiction. From the increase in volume, one would think that the mean distance apart of the ions in a liquid electrolyte would be greater than in its parent crystal. On the other hand, from the fact that the ions in a fused salt are slightly closer together than in the solid lattice. 

Internuclear Distances in an Ionic Crystal and the Corresponding Fused Salt 

Salt Distance between Oppositely Charged Ions (pm)  

Before an answer is given to this central question, it is necessary to retrace the steps that have been taken in respect to Fig. 5.6. One examines how it was obtained because quantitative knowledge of the short-range order which does exist (dotted line in Fig. 5.6) is vital to understanding the liquidity of molten salts. 

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