Ion-Association Reaction of Rb+ and Br- in 2-Methylpropan-2-ol + Water Mixtures

The molar conductivity of RbBr solutions in 2-methylpropan-2-ol (tert-butanol) + water mixtures at alcohol mass fractions of 0.70, 0.80 and 0.90 was measured at temperatures from 288.15 to 308.15 K at 5 K intervals. The limiting molar conductivity (Lambda(o)) and the ion-pair formation constant (K-A(o)) were determined by the Lee-Wheaton conductivity equation. Thermodynamic quantities, Gibbs energy (Delta G(o)), enthalpy (Delta H-o) and entropy (Delta S-o), for the ion-association reaction were derived from the temperature dependence of K-A(o); the activation energy of the ionic movement (Delta H*) was derived from the temperature dependence of Lambda(o). These values were compared with those obtained earlier for HBr and NaBr in the same mixtures.