ON THE COMPOSITION OF DILUTE ALKALI METALAMMONIA SOLUTIONS.
Technical rept. no. 13,
BRANDEIS UNIV WALTHAM MASS
Pagination or Media Count:
Dilute solutions of the alkali metals in liquid ammonia are assumed to consist of the following constituents M, the solvated metal cation S, the solvent M-, the solvated metal anion S-, the solvent anion solvated electron the ion-pairs M.M- and M.S-. These species are assumed to be in equilibrium via M 2S- reversibly yields M- 2S and M A- reversibly yields M.A-, where A- is either M- or S-. With generally good results being obtained, the foregoing model has been applied to account for the following properties of alkali metal-ammonia solutions which are more dilute than about 0.10 M 1 the spin paramagnetic susceptibilities reported by Hutchison and Pastor 2 the vapor-pressure depression results of Kraus 3 the electrical conductances measured by Kraus and the temperature coefficients of conductance, reported by Gibson and Phipps 4 the Knight shifts for N14 and Na23, reported by McConnell and Holm, Acrivos and Pitzer and OReilly 5 the optical absorption results of Gold and Jolly, and those of Dye and Douthit. An a postiori argument supports the neglect of ion-triples for the solutions which have been considered, and reinforces a distinction to be made between the metal anion Na- and the analogous ion-triple S-.Na.S-.