Density, speed of sound, viscosity and refractive index properties of aqueous solutions of vitamins B1.HCl and B6.HCl at temperatures (278.15, 288.15, and 298.15) K

The experimental values of density (ρ), speed of sound (u), absolute viscosity (η) and refractive index (nD) properties are reported for aqueous solutions of thiamine hydrochloride (vitamin B1.HCl) and pyridoxine hydrochloride (vitamin B6.HCl) within the concentration range (0.01 to 0.55) mol ⋅ kg−1 at three different temperatures, viz. T/K = 278.15, 288.15, and 298.15. Using experimental data, different derived parameters such as the apparent molar volume of solute (ϕVϕV), isentropic compressibility of solution (βS), apparent molar isentropic compressibility of solute (ϕKSϕKS) and relative viscosity of solution (ηr) have been computed. The limiting values of apparent molar volume (ϕV0) and apparent molar isentropic compressibility (ϕKS0) have been obtained. The limiting apparent molar expansivity (ϕE0) of solute, coefficient of thermal expansion (α∗) and hydration numbers (nh) of above vitamins in the aqueous medium have also been estimated. The experimental values of relative viscosity are used to calculate the Jones–Dole equation viscosity A and B coefficients for the hydrochlorides. The temperature coefficients of B i.e. (dB/dT) for these solutes have been used to study water structure making and breaking effects due to cations. Further, a discussion is made on the basis of solute–solute and solute–solvent interactions.

Figure optionsDownload as PowerPoint slideHighlights
► Study of aqueous solutions of vitamins B1.HCl and B6.HCl at different temperatures has been presented.
► These are important vitamins.
► Different interactions among solute and solvents have been investigated.
► The results are interpreted in terms of water structure making and breaking effects due to cations.