CONDUCTANCE STUDIES OF ALKALI-METAL CHLORIDES AND BROMIDES IN AQUEOUSBINARY-MIXTURES OF TETRAHYDROFURAN AT 25-DEGREES

Precise conductance measurements are reported for alkali metal chlorid es and bromides, MX (M+ = Li, Na, K, Rb and Cs ; X- = Cl and Br) in te trahydrofuran (THF) + water mixtures at 25-degrees. The limiting molar conductivity (LAMBDA0) the association constant (KA) and association distance (R) in the solvent mixtures have been evaluated using the Fuo ss conductance equation (1978). The analysis of data indicates that th e electrolytes are most unassociated at 0.059 mole fraction of THF, wh ereas at 0.143, 0.273 and 0.500 mole fraction of THF, the association was very strong. The values for alkali metal cations (anion being the same) are found to be in the order : Li+ < Na+ < K+ < Rb+ < Cs+. The r esults have been explained in terms of ion-solvent interactions and st ructural changes in the mixed solvents.