電解質水溶液在化工製程，環境工程，醫學工程，石油工業，石化工業等，都是常遭遇到的混合物。因為電解質的加入，使得原本只含有溶劑的液體，會因此而改變其原有的熱力學性質，也使得溶液偏離了理想性。為了描述溶液偏離理想溶液的程度，通常引入活性係數作為考慮。而Lin and Lee (2003)在其發表的論文中提出電解質水溶液中，離子活性係數肇因於離子水合作用之部分，即是電解質水溶液中離子與溶劑分子之間短距離作用力，以媒合參數(solvation parameter)表示，而肇因於離子與離子之間的長距離作用力之部分則以趨近參數(approaching parameter)表示。相對於非電解質的熱力學性質，電解質水溶液的熱力學性質的文獻數據較少，所以本研究便應用Lin and Lee (2003)所提出之個別離子活性係數模式，使用已經求得之趨近參數以及媒合參數並搭配熱力學之方程式，來對11種單一電解質水溶液之汽化熱(enthalpy of vaporization)、18種單一電解質水溶液之凝固點下降(depression of Freezing point)、以及13種單一電解質水溶液之沸點上升(elevation of Boiling point)進行預估，並將預估的結果與文獻值進行比較，並得到了不錯的結果。 Electrolyte solutions are always met in the process of chemical engineering, environment engineering, biomedical engineering, the petroleum industry, and petrifaction industry. Because of adding the electrolytes, the thermodynamic properties of the original solvent were changed, and were made deviation from ideality. In order to describe the degree of the solution deviating from the ideal solution, we usually take activity coefficient for consideration. In the study of Lin and Lee (2003), it was proposed that, in the electrolyte solution, the ion activity coefficient is contributed by two parts: one is salvation which is expressed by salvation parameter which is the short-range interaction between ion and water molecule, the other is the long-range interaction between ions which is expressed by approaching parameter. In this study, we use the ion activity coefficient model of Lin and Lee (2003), the known salvation parameter and approaching parameter, and using some thermodynamic equations to calculate the enthalpies of vaporization of 11 kinds of single electrolyte solutions, freezing point depressions of 18 kinds of single electrolyte solutions, and boiling point elevations of 13 kinds of the single electrolyte solutions then compare them with the literature data, and the results were predicted successfully.