ENTHALPIES OF TRANSFER OF CO(II), NI(II) AND CU(II) IONS IN ACETONITRILE-WATER MIXTURES

The enthalpies of solution have been measured for Ni(CLO(4))(2) . 6H(2 )O, Cu(ClO4)(2) . 6H(2)O and water in acetonitrile-water mixtures over the whole range of solvent composition. These data have been used for calculation of the enthalpies of transfer of Ni(ClO4)(2) and Cu(ClO4) (2) from water to the mixtures. In the acetonitrile-rich mixtures an a lternative method of determining the enthalpies of transfer has also b een applied. The results, as well as our previous data for Co(ClO4)(2) [1], coupled with the enthalpies of transfer of perchlorate ion repor ted earlier [2], have allowed the determination of the enthalpies of t ransfer for Co(II), Ni(II) and Cu(II) ions in acetonitrile-water mixtu res. The variation of the ionic enthalpies of transfer with solvent co mposition is discussed in terms of the properties of the ions and the solvents.