EFFECT OF SOLVENT STRUCTURE ON THE TRANSPORT AND THERMODYNAMIC PROPERTIES OF ELECTROLYTE-SOLUTIONS - CONDUCTANCE OF POTASSIUM-NITRATE AND SODIUM-BROMIDE IN WATER PLUS SULFOLANE MIXTURES AT 25-DEGREES-C

The conductance of potassium nitrate and sodium bromide in mixtures of water and sulpholane covering the dielectric constant range 80 greate r-than-or-equal-to D greater-than-or-equal-to 60 has been measured. Th ese data and other previous data on potassium iodide in the same solve nt mixtures were analyzed using the Fuoss 1980 equation in order to ob tain the limiting molar conductances LAMBDA0, the pairing distances R and the conductometric association constants K(lambda). The difference s in the Gibbs energy DELTAG per molecule between paired and unpaired ions were also calculated, setting DELTAG = - kT In(K(lambda)/V(M)), w here V(M) is the molar volume (in liters) of the solvent. The conventi onal association constant and the thermodynamic properties of the ion pairing are discussed with respect to the current information concerni ng the internal structure of the solvent mixtures and the specific pro perties of the ions.