A Physicochemical And Electrochemical Study Of Aqueous Thiaminium Dichloride At 250c

Abstract

Investigation of density, viscosity, refractive index, conductivity and diffusivity of aqueous Thiaminium dichloride solutions at 250C have been carried out over the concentration range 0 -_1M. The concentration dependence of density and related quantities - apparent and partial molal volumes- have been obtained and the latter agrees with Masson's theory. The values of the latter quantities at infinite dilution have been obtained as ¢O = Vo = 157 ± 2 cm3 mol-1 and the ionic contribution have been discussed. The variation of viscosity, refractive index and molal refractivity with concentration have also been shown. The viscosity results support the Jones-Dole and Einstein's theories, with the A and B coefficients having magnitudes that confirm strong interactions between the solute and solvent particles. Bion values have been discussed. The value of molal refractivity at infinite dilution, [Rapp]ODc70.0 ±1.4 cm3 moLr r , suggests the presence of loosely bound or delocalized electrons and therefore high polarisability of some solution constituents. The concentration variation of conductivity can be explained by proposing higher valency ionic species resulting from a two step ion association scheme with association constants being Kl = 1/Kal and K2=1/Ka2 1 mol- 1 . Kal and Kaz values are calculated from literature1 8 pKa1 and pKaa values respectively , The mixture rule is more appropriate to this situation as opposed to Kohlrausch's isoionic rule. The limiting ionic equivalent conductivity of the ions involved have been found to be; \oThi + = 29.3 ± 0.3, X'ThiHZ+ = 35. 8 ± O. 3 and AT h:i H 3 + = 41. 3 . 0 ± O. 3 S cm2 ( gequiv. )-1 .equivalent The electrolytes conductivity was infinite dilution (g equiv.)-1. The variation of 532.7 ± 0.5 S cm2 the differential diffusion coefficient, determined within an accuracy of 0.5 % using a modified diaphragm cell, has been established and with concentration the electrolyte's infinite dilution value, DO, was 1 . 275 X 10- 5 cm2 s-1· These results indicate strong ion-solvent and solvent-solvent interactions. ion-ion,