Thermodynamic Investigation of NaClO3 Solubility in the Mixed Solvent Medium and the Related Ion – Pair Formation at Different Temperatures

Abstract

Using the evaporating method, the solubility of sodium chlorate was determined in the various mixed solvents (water + ethanol + propanol) at various temperatures. The results showed that the solubility of NaClO 3 decreases with increasing the mass percent of ethanol and propanol. On the other hand, the solubility of NaClO 3 increases with increasing the temperature .In addition, the equilibrium constant of ion pair formation, K IP, for the reaction Na + (aq) + ClO 3 - (aq) Na + ClO 3 - (Ion Pair) was estimated upon Fuoss contact ion pair model and then, the values of ion-pair concentrations were determined by using the extended Debye-HA¼ckel model and iteration calculations in various mixed solvents and various temperatures . Finally the value of thermodynamic solubility product constant, K sp(th) , and the values  I”H ° , I” S ° and I” G ° of  and of ion-pair formation were estimated in the mixed solvent media.