Conductometric Study of Ammonium Bromide in 2-Butanol + Water Mixtures

Vesna Sokol,* Renato Tomaš and Ivo Tominić

Faculty of Chemistry and Technology, University of Split, N. Tesle 10, 21000 Split, Croatia
* Corresponding author: E-mail: vsokol@ktf-split.hr

Abstract
Molar conductivities of dilute solutions of ammonium bromide in binary mixtures of 2-butanol and water were measured in the temperature range from 288.15 to 308.15 K at 5 K intervals. The limiting molar conductivity ( Λ_o) and the ionpair formation constant (K_A) were determined by the Lee-Wheaton conductivity equation. Thermodynamic quantities, Gibbs energy (ΔG^o), enthalpy (ΔH^o) and entropy (ΔS^o), for the ion-association reaction were derived from the temperature dependence of K_A. The activation energy of the ionic movement (ΔH⁺⁺) was derived from the temperature dependence of Λ_o. The obtained thermodynamic quantities, together with Walden product, were compared to those for alkali metal bromides and interpreted in terms of the ionic size, as well as solvent basicity, structure and permittivity.

Keywords: Ammonium bromide, 2-butanol + water mixtures, association to ion-pairs, thermodynamic quantities