ION-PAIRING OF AMMONIUM-NITRATE IN METHANOL

The recent suggestion (J. Phys. Chem. 1991, 95, 897) that the ion-pair association constant of ammonium nitrate in methanol is K2 much-greater-than 10 m3/mol (10(4) M-1) at about 293 K would have interesting implications for our embryonic understanding of solvent effects, if it were correct. Electrical conductance measurements of solutions at concentrations from 1 to 995 mol/m3 demonstrate that ammonium nitrate behaves as a normal, strong electrolyte in methanol. The conductances are fitted by the Onsager-Fuoss equation, the second term of which contributes the greatest reduction in conductance and corresponds to the ion-atmosphere (long-range interactions) model of Milner, Debye, and Huckel. A new attack on the theory of concentrated electrolyte solutions should be made by computer simulation.