Alkali metal chlorides, molal

Figure 22 shows the salt effects for monovalent and divalent cations (alkali and alkali earth metals) chlorides. For all these salts, the phase transitions took place reversibly and were discontinuous as functions of salt molality. The efficiency of salts in contracting gels was almost the same for alkali metals chlorides (monovalent cations) except Li+, whereas it was slightly dependent on alkali earth metals (divalent cations) in inverse order of ionic radii, Mg2+ < Ca2+ < Sr2+ < Ba2+. 

In connection with Vaslow s measurements (150) of the apparent molal volumes of the alkali metal chlorides in solutions, we call attention to the earlier measurements by Halasey on the temperature dependence of the partial molal volumes. These measurements suggest (31) that the... 

The above-mentioned papers [169, 170] report the determination of the upper limit of basicity which can be achieved in alkali metal chlorides and the melts containing polyvalent metal chlorides as constituent parts of the melt. Owing to their small ionic radii and high charge, these cations demonstrate elevated acidic properties. Increase of the initial molality of oxide ions finally results in the precipitation of the solid oxide, formed by such acidic cations, from the saturated solution. The oxoacidity function corresponding to this limit may be described by the following equation ... 

Vaslow F (1966) The apparent molal volumes of the alkali metal chlorides in aqueous solution and evidence for salt-induced transition structure. J Phys Chem 70 2286-2294... 

A better method for studying the alkali metal cation-soap anion interaction on the surface, according to Weil (58), is to assume a similarity between surface behavior and solution behavior and to use the activity coefficient of the solute in the solution as the parameter to account for surface behavior. By plotting activity coefficients as a function of the molality for the salts of the alkali metals (7, 26), the resulting order of the curves of the weak acids (formates, acetates, hydroxides) is the reverse of that found for the strong acids (chlorides, bromides, nitrates, chlorates, sulfates). The activity curves of the acetate salts can be used as the counterparts for the long-chain fatty acid salts, while those for the chlorides can be the analogs of the alkyl sulfates. The scheme is speculative in that the fatty acid and alkyl sulfate salts micellize, and acetate and chloride do not. 

Fig. 5.9 Molal chemical shifts for the alkali metal and alkaline earth metal chlorides in aqueous solution plotted against the polarizing strength of the cation estimated as zjr (Pauling scale). The data shown as (o) have been corrected for the contribution of CP, and represent estimates of the cation contribution (see text).

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