THE SPECIES AND COMPOSITION OF DILUTE ALKALI METAL-AMMONIA SOLUTIONS. I.
Abstract
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 solvated ion-pairs M(+). M(-) and M(+). S(-). The presence of the solvated metal anion M(-) is justified on the basis of the observed existence of stable alkali metal anions in the gas phase. The absence of solvated metal M, usually assumed to be a constituent of these solutions, is justified in part by a thermodynamic estimate of its instability with respect to disproportionation to yield the solvated cation and solvated anion of the metal; the optical and electrical properties of condensed layers of mixtures of ammonia and the alkali metals at very low temperatures favor this view. The solvated solvent anion S(-) is favored as a model for the solvated electron on the basis of Knight shift data for the spin density on N-14, which is extremely close in value to that of sodium, with which ammonia is isoelectronic. These species are assumed to be in equilibrium via M(+) + 2S(-) = M(-) + 2S and M(+) + A(-) = M(+) . A(-), where A(-) is either M(-) or S(-). For simplicity, the activity coefficient of each species is assumed to be given by the extended theory of Debye and Huckel, with a fixed value of 5.5A for the interionic size parameter. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 1965
- Accession Number
- AD0465124
Entities
People
- Charles Guttman
- Sidney Golden
- Thomas R. Tuttle Jr.
Organizations
- Brandeis University