Studies on Volumetric and Viscometric Properties on N-Acetylcysteine in Acetic Acid-Water Binary and Ternary Mixtures

Abstract

The density and viscosity of NAC (0.10 to 1.00) mol.L−1 in H2O, CH3COOH and H2O–CH3COOH mixed solutions were measured and analyzed over the whole concentration range at (298.15, 303.15, 308.15, 313.15 and 318.15) K temperatures. The apparent molar volumes were obtained from the experimental density data. In the NAC– H2O and NAC in [9:1] [H2O–CH3COOH] solvent systems the apparent molar volume of NAC increases, whereas in the NAC–CH3COOH and NAC in [4:1], [7:3] and [3:2] [H2O–CH3COOH] solvent systems it decreases. With the help of experimental density data apparent molar volume at infinite dilution, and Sv values were also calculated. The apparent molar volume at infinite dilution gives an idea about the presence of solutesolvent interactions while Sv is the experimental slopes which give an idea about the prevailing solutesolute interactions in the mixtures. The calculated data indicate that there may be solute-solute and solute-solvent interactions present in the binary and ternary solutions. Binary and ternary systems showed rapid increase of viscosity values with the increase in NAC concentration but the values of viscosity decreased with the increase of temperature for all the experimented system. The viscosity data were employed to find out the viscosity (A, B) coefficients, change of free energy, G*, change of enthalpy, H* as well as change of entropy, S*. From these thermodynamic parameters state of the spontaneity of the investigated systems were identified. Moreover, negative A and positive B co-efficient values suggesting that weak solutesolute but strong solute-solvent interaction present in the binary and ternary solution. On the basis of this data, the predominant molecular interactions occurring between NAC– H2O and NAC in [9:1] [H2O–CH3COOH] solvent systems were found to be solute-solute interaction, whereas in NAC–CH3COOH and NAC in [4:1], [7:3] and [3:2] [H2O– CH3COOH] solvent systems solute-solvent interaction were predominant.