Thermodynamics Research Center / ThermoML | Journal of Chemical Thermodynamics

ABSTRACT

Apparent molar volumes, apparent isentropic compressibilities, and viscosity B-coefficients for 1-ethyl-3-methylimidazolium bromide (EmimBr) in aqueous di-potassium hydrogen phosphate (K2HPO4) solutions with salt weight fractions (w_s = 0.00, 0.10, 0.15, and 0.20) and potassium di-hydrogen phosphate (KH2PO4) solutions with salt weight fractions (ws = 0.00, 0.04, 0.07, and 0.10) have been determined from solution density, sound velocity and viscosity measurements at temperatures over the range (298.15 to 318.15) K as function of concentration of 1-ethyl-3-methylimidazolium bromide (EmimBr). In the investigated temperature range, the relation: V = a_0 + a_1 T + a_2 T^2; has been used to describe the temperature dependence of the standard partial molar volumes. These results have, in conjunction with the results obtained in pure water, been used to deduce the standard volumes of transfer and viscosity B-coefficients of transfer for 1-ethyl-3-methylimidazolium bromide from water to aqueous K2HPO4 and KH2PO4 solutions for rationalizing various interactions in the ternary solutions. The structure making or breaking ability of 1-ethyl-3-methylimidazolium bromide has been discussed in terms of the sign of a second temperature deritive of apparent molar volume. An increase in the transfer volume of 1-ethyl-3-methylimidazolium bromide with increasing phosphate salts concentration has been explained by Friedman-Krishnan co-sphere model. The activation parameters of viscous flow for the ternary solutions investigated were also determined and discussed by the application of transition state theory.