ENTHALPIES OF MIXING IN SAMARIUM(III) NITRATE SOLVATE-DILUENT AND NEODYMIUM(III) NITRATE SOLVATE-LANTHANIDE(III) NITRATE SOLVATE SYSTEMS

The enthalpies of mixing of [Sm(NO3)(3) .S-3] [S is tri-n-bytul phosph ate (TBP) or diisooctyl methylphosphonate (DIOMP)] with hexane, benzen e, carbon tetrachloride, and chloroform and of [Nd(NO3)(3) . 3TBP] wit h [Ln(NO3)(3) . 3TBP] [Ln = La, Ce(III), and Pr(III)] have been determ ined calorimetrically at 298.15 K. The enthalpies of mixing h(E) are d escribed by the equation h(E) = A(h)X(d)X(S), where X(d) and X(S) are the mole fractions of the components. The values of A(h) are positive for hexane, become more negative in the series carbon tetrachloride, b enzene, and chloroform, and decrease (in the absolute value) in going from [Sm(NO3)(3) . 3TBP] to [Sm(NO3)(3) . 3DIOMP], Systems with samari um are characterized by positive values A(h), which increase from Pr(I II) to La(III).