Lattice energies of alkali metal nitrates and related thermodynamic properties

Abstract

Correlations between the viscosity B-coefficient of the Jones-Dole equation for aqueous solutions of alkali metal salts and the enthalpy of hydration of the gaseous monatomic constituent ions have been established. The assumption that corresponding behaviour applies to alkali metal nitrates appears justified, and the standard enthalpies of solution of the gaseous ions M⁺(g) and NO₃(g) have been estimated and used to derive the lattice energies of MNO₃(c) [M = Li, Na, K, Rb, Cs]. Total lattice potential energies of the salt are (in kJ mol⁻¹) LiNO₃, 848; NaNO₃, 755; KNO₃, 685; RbNO., 662; CsNO₃, 648. By use of such results in conjunction with other thermochemical data, the electron affinity of NO ₃(g) has been evaluated, Euo⁻ ₃ = 3 98 ± 0 25 eV; this magnitude agrees satisfactorily with recent experimental results.