Dissociation constant studies of citric acid at different temperatures and in different organic-water solvent systems

Thermodynamic dissociation constants of citric acid is being studied at different temperatures from 25 to 50 degrees C at 5 degrees C interval and in 10, 20, 30 and 40 percent v/v dioxane-water, methanol-water, ethanol-water and acetonitrile-water solvent systems. The resolution of acid strength in dioxane, methanol, ethanol and acetonitrile relative to that in water has been determined Thermodynamic parameters that are Gibb's free energy (Delta G), enthalpy (Delta H) and entropy (Delta S) at different temperature have also been studied. Changes in pKn values on account of dielectric constant and hydrogen bonding have been discussed. Result shows greater resolution in mixed organic solvents than in water.