ENTHALPY OF INTERACTION OF SOME ELECTROLYTES WITH 2-METHYL-2-BUTANOL IN WATER AT 25-DEGREES-C

Enthalpies of mixing in water of 2-methyl-2-butanol with several elect rolytes (alkali-metal halides, tetra-n-alkylammonium bromides, Ph(4)PC l, Ph(4)AsCl and NaPh(4)B) have been determined by flow microcalorimet ry at 25 degrees C. Enthalpic pair interaction coefficients, h(NE), of the virial expansion of the excess enthalpy were calculated. All coef ficients are positive and increase as the anionic size increases in an ionic series of alkali-metal halides. A linear correlation between h(N E) and the number of carbon atoms in the apolar group of R(4)NBr is ob served. For alkali-metal halides coefficients h(NE) depend mainly on t he partial desolvation of halides, and for hydrophobic electrolytes bo th the partial desolvation of halide ions and hydrophobic interactions are the leading factors in the value of h(NE).