Vapor Pressure of the Liquid Attached to the Surface of Common Salt

Caking Mechanism of Sodium Chloride (Part 5)

Abstract

In his preveous paper, the author discussed a relation of liquid attached to the surface of crystals to the caking of common salt from the view-point of the deposition of salt when cooled. In this paper, caking tendency was discussed from the view-point of vapor pressure of the liquid. And vapor pressure of the liquid was calculated from Sugiyama's formula by treating it as an oceanic quinary system.
1. The liquid saturated only with sodium chloride has higher vapor pressure. Therefore, higher caking tendency (shown in Fig. 2) is observed as purity of sodium chloride increases and the content of either potassium or sulfate ion increases.
2. The liquid saturated with sodium chloride and more than one salt other than sodium chloride has higher vapor pressure and higher caking tendency (shown in Fig. 3), as the content of either potassium or sulfate ion increases.
3. The vapor pressure and caking tendency of common salt made from the oceanic quinary system are discussed from the above-mentioned figures.