Volumetric and viscometric studies of nicotinic acid in aqueous solutions of sodium malonate at T = (298.15–318.15) K

• Densities, viscosities and refractive indexes of nicotinic acid in aqueous sodium malonate solutions measured.
• Apparent molar volume (ϕVϕV) and standard molar volume (ϕV0) determined.
• Viscosity B-coefficient was determined.
• Effect of molality, solute structure and temperature analyzed in terms of ion–ion and ion–solvent interactions.
• Nicotinic acid behaves as a long range structure maker.

Densities and viscosities for the solutions of nicotinic acid in aqueous sodium malonate solutions with several molalities (msodium malonatemsodium malonate = 0.000, 0.005, 0.010, 0.015 and 0.020 mol·kg-1mol·kg-1) of sodium malonate were determined at T = (298.15–318.15) K and at pressure p = 101 kPa. Apparent molar volume (ϕVϕV standard partial molar volume (ϕV0 the slope (SV∗), standard isobaric partial molar expansibility (ϕE0) and its temperature dependence (∂ϕE0/∂T)P, the viscosity B  -coefficient and solvation number (SnSn), etc., were determined. Using the experimental data viscosity B  -coefficients were further utilized to obtain the free energies of activation of viscous flow per mole of the solvents (Δμ10≠) and of the solute (Δμ20≠). Effects of molality, solute structure and temperature on all these parameters were analyzed in term of ion–ion and ion–solvent interactions; results revealed that the solutions are characterized predominantly by ion–solvent interactions and nicotinic acid behaves as a long-range structure maker.

Different possible interaction between nicotinic acid and sodium malonate in aqueous media.Figure optionsDownload as PowerPoint slide