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The conductivity of thiocyanates methyl alcohol

1930; Royal Society; Volume: 127; Issue: 804 Linguagem: Inglês

10.1098/rspa.1930.0053

2053-9150

Augusta Unmack, D. M. Murray-Rust, Harold Hartley,

Chemical and Physical Properties in Aqueous Solutions

This investigation is a continuation of the work of Frazer and Hartley on the conductivity of uni-univalent salts in methyl alcohol, which dealt mainly with the halides and nitrates of the alkali metals. The thiocyanates are a particularly important class of salts in the investigation of non-aqueous solutions, as the thiocyanates of the alkali metals are soluble in a number of solvents, while many of the corresponding salts of other acids are too sparingly soluble to admit of investigation. They thus afford an opportunity of com­paring the behaviour of ions of the alkali metals in various solvents and of determining their mobilities. The thiocyanates of many of the divalent metals are soluble also, but their preparation in an anhydrous condition is much more difficult. Since the publication of Frazer and Hartley’s paper Onsager has modified the Debye-Hückel theory of the conductivity of electrolytes by taking into account the Brownian motion of the ions, thereby bringing it into much closer agreement with experimental results. In water the agreement is good both for uni-univalent and di-univalent electrolytes, and Onsager used Frazer and Hartley’s results to show how well his equation represented the behaviour of uni-univalent electrolytes in methyl alcohol. In this solvent, however, there are systematic deviations between the calculated and observed values of the conductivities, which indicate that association between the ions increases with the atomic number of the alkali metal. This has been confirmed by the results described in this paper and an explanation is discussed later.