Volumetric, ultrasonic speed, and viscometric studies of salbutamol sulphate in aqueous methanol solution at different temperatures

Values of density, ultrasonic speed, and viscosity of salbutamol sulphate (SBS) have been determined in aqueous methanol solutions at T = (303.15, 308.15, 313.15, and 318.15) K. The apparent molar volume Vφ  , partial molar volume Vϕ0, molar expansivity E20, isobaric thermal expansion coefficient (α2), and second derivative of infinite dilution of partial molar volume with temperature ∂2Vϕ0/∂T2 are evaluated using density data. Isentropic compressibility βs, change in isothermal compressibility Δβs  , relative change in isentropic compressibility (Δβs/βs0), apparent molar compressibility Kφ   and partial molar compressibility Kϕ0 values are calculated by using data on density with ultrasonic speed. Viscosity B-coefficient, variation of B-coefficient with temperature, i.e.,dB/dT  , free energy of activation per mole of solvent Δμ10∗ and solute Δμ20∗ are evaluated using viscosity data. The above parameters are used to interpret the solute–solute, solute–solvent interactions and structure making/breaking ability of the drug in the given aqueous methanol solution.