Volumetric and Viscosity Studies of Aqueous Solutions of the Potassium Salt of Penicillin-G at Different Temperatures and at Ambient Pressure

摘要

Density and viscosity measurements are reported for aqueous solutions of the potassium salt of penicillin-G at different temperatures(293.15 K to 308.15 K)and at ambient pressure.The density data are used to obtain apparent molar volumes of the potassium salt of penicillin-G(PGK).Also,the coefficient of thermal expansion and apparent molar expansivity data has been obtained using the density data at different temperatures.The relative viscosities(eta_r)and the viscosity A,B,and D coefficients in the Jones-Dole equation eta_r=1+Ac~(1/2)+Bc+Dc2,with c=concentration of the potassium salt of penicillin-G in aqueous solutions(0.005 mol·dm~(-3)to 0.12 mol·dm~(-3)),have been determined.The values of the B and D coefficients were found to be high compared to simple 1:1 electrolytes.The values of the A coefficient do not show any trend as a function of temperature;however,the B coefficient decreases with an increase in temperature.The results are explained in terms of hydrophobic hydration of the anion and hydrophobic interactions between penicillin-G molecules in the premicellar region.