The dielectric polarisation and apparent molar volume studies of ethanol, <i>tert</i>-butanol and tetrabutylammonium bromide in nonpolar solvents

Abstract

Dielectric constant (e), density <i>(d) </i> and refractive index <i>(n) </i> measurements at 25°C for solutions of ethanol, <i>tert-</i>butanolin carbontetrachloride and of tetrabutylammonium bromide in benzene and carbontetrachloride (1 to 30 x 10^-3 weight fraction of solute) are reported. Solute polarisations (P₂) and apparent molar volumes (φ_v) of the solute have been evaluated as a function of solute weight fraction. The variation of these parameters with concentration is explained in the case of ethanol and <i>tert</i>-butanol solutes in terms of association in the forms of dimer and higher aggregate formation in solution. The infinite dilution properties enable to calculate the dipole moments and partial volumes of the monomer in the case of alcohols. The measurements for tetrabutylammonium bromide in C₆H₆ and CCl₄ show that this solute molecule exhibits highly nonlinear behaviour in limiting concentration range. The results are explained on the basis of micellization, triple ion and ion pair formation in the studied concentration range. The values of limiting apparent volume of the salt in nonaqueous solvents are also compared with similar data reported for aqueous solutions.