Basic Sciences of Medicine 2012, 1(2): 1-5 DOI: 10.5923/j.medicine.20120102.01 Molar Solubility, Solvation and Conductivity Association Parameters of Sodium Fluoride in Mixed Aqueous-Ethanol Solvents at Different Temperatures Esam A. Gomaa * , R. M. Galal Chemistry Department, Faculty of Science, Mansoura University, Mansoura, 35516, Egypt Abstract This paper reports the results on the molar solubility (MS), refractive index (RIN) and molar electrical con- ductance (EC) of the saturated NaF at different temperatures (293.15, 303.15 and 313.15 K) in mixed ethanol (ETOH) –water solvents. From the experimental part, the molar refraction (RM), limiting molar conductance (LEC), association constants (KASS), free energies of association (GASS) were determined for all solutions by using simple equation from the Shedlovslay model of conductivity.Results predicted the exothermic behaviour of the process in most of the cases. All the measured and calculated parameters for solvation (solubility parameters) and association (conductivity parameters) are in- creased by increasing the mole fraction of ethanol in the mixtures. This indicates more solute-solvent interaction by more adding ethanol in the mixed solvents.The solubility; conductivity and different thermodynamic data calculated here can easily used for the industial determination of sodium fluoride. Keywords Molar Solubility, Refractive Index, Conductance, Association Constant, Free Energies of Association 1. Introduction Fluoride in drinking water was originally added to prevent tooth decay. Studies hve now shown that fluoride causes dental decay. Studies have now shown that fluoride causes dental fluorosis in 10% of the population. Research is also linking fluoride to increased risk of cancer (particularly bone cancer), gene mutations , reproductive problems neuro- toxicity ( hyper or depressed activity) bone fuorosis (de- creasing density) . Fluoride exposure disrupt the synthesis of collagen and leads to breakdown of collagen in bone , muscle. skin, cartilage , lungs , kidney and trachea[1-4] . For indus- trial uses sodium fluoride is commonly uses in pesticides, including fungicides and insecticides. Various types of ad- hesives and glues use sodium fluoride as a preservative. Sodium fluoride is also used in making steel and aluminium products. Other industrial uses for sodium fluoride include glass frosting, stainless steel pickling and wood preserva- tion[5].Our purpose is to give new data for solubility and conductivity of sodium fluoride in different ethanol water solvents which can help for the industrial, analytical and biological determination of it. The solubility of an electrolyte is influenced by a wide range of factors, including ion association ,variation in ionic * Corresponding author: esam1947@yahoo.com (Esam A. Gomaa) Published online at http://journal.sapub.org/medicine Copyright © 2012 Scientific & Academic Publishing. All Rights Reserved activity coefficients , complexation and temperature. Solu- bility is an equilibrium property enable to thermodynamic analysis provided that sufficient information is available[6]. Conductivity explains the ion aggregation and the ion solvation and the competitation between them .Two ascpects determine the role of the solvent, its bulk properties and its electron – pair donor and electron – pair acceptor abilities[7]. Molar solubility (MS) and electrical conductance (EC) is very important in elucidating not only the behaviour of ions in solution but also in the study of solution structured effects and the preferential solvation of ions by a solvent[8,9]. Recently, electrical conductance (EC) studies were done in non-aqueous solvents with the intension of investigation ion-ion and ion-solvent interactions[10,11]. In continuation of this we studied the conducting behaviour of NaF in water, ethanol[EtOH] and their mixtures at different temperatures to elucidate the solvation and association behaviours of NaF under prevailing conditions. 2. Experimental Sodium fluoride 99%, from Aldrich chemicals Co. Ltd., Gillincham, Dorest – England was used. Absolute ethanol of Al-Gomhoria supplements was used, without further puri- fication. The saturated solutions of sodium fluoride were prepared by dissolving it in H 2 O-ETOH mixtures in test tubes. The tubes were placed in a shaken thermostat of the type Assistant for a period of four days, followed by another two days without shaking to reach the necessary equilibrium.