Magneto optical rotatory dispersion studies of simple electrolyte solutions. Part 3.—Measurements on solutions of chlorides and bromides of some group II metals

Abstract

The m.o.r.d. of concentrated aqueous solutions of MgCl₂, CaCl₂, SrCl₂, BaCl₂, BaCl₂ CaBr₂, SrBr₂ and BaBr₂ were measured in the wavelength range 350–600 nm. The variation of the specific rotations in terms of the effects of the solutions with concentration of solute and the molar magnetic rotations could be interpreted in terms of the effects of the solutes upon the competing processes of solvent structure-making and structure-breaking. There was a correlation between molar magnetic rotation and total ionic volume. The changes in rotation with wavelength were fitted to a one-term Drude equation and the constants of this equation, K and λ₀, were calculated by the Biot–Lowry method. The values of λ₀, however, could not be identified with the peak position of the halide ion charge-transfer-to-solvent spectrum and the Drude equation is merely a convenient empirical relationship for the m.o.r.d. results in the wavelength range studied. The variation of K with solute concentration paralleled the relative effects of cations and anions on the structure of water.