CONDUCTANCE OF "N-N'-DIPHENYL-S-ALKYLISOTHIOURONIUM BROMIDES IN METHANOL-WATER MIXTURES AT 25-DEGREES-C

The conductance of N-N -Di phenyl-S-A 1 kyl i sothi ouroni um bromi des is measured in methanol-water mixtures covering 32.63 < D <66.36 at 25°C. The data are ana lysed using the Fuoss-Onsager equation on a PDP 11/70 computer to get A , KA, and aO. A n shows dependence on the solvent composition.The ion-size parameter, aO, decreases with decrease in dielectric constant up to D = 57.14 and increase thereafter. Log KA vs. liD is not linear,indicating that solvent separated-ion pairs are found in systems characteri­zed by strong hydrogen bonding. 

F M A EL HALIM ,M A MAHMOUD ,A A HASNEIN ,N H EL HAMMY ,