On the Friedman-Pitzer higher order electrostatic terms for unsymmetrical mixing of ions of the same sign in electrolyte solutions
✍ Scribed by Farzad Deyhimi
- Publisher
- Elsevier Science
- Year
- 2007
- Tongue
- English
- Weight
- 262 KB
- Volume
- 135
- Category
- Article
- ISSN
- 0167-7322
No coin nor oath required. For personal study only.
✦ Synopsis
Pitzer derived useful equations in integral forms for calculating the effect of higher order electrostatic terms for unsymmetrical mixing of ions of the same sign in electrolyte solutions (K.S. Pitzer, J. Solution Chem., 4 (1975) 249). Given that, the use of these integral forms requires numerical calculations with computer, therefore, he has also presented two other practical approximate expressions (in series forms) for easier evaluation of these effects. In addition, he confirmed the adequacy and accuracy of these equations, or the so-called "J(x) functions", for practical calculations with experimental data. However, instead of giving also explicit forms of the corresponding derivative functions (i.e. "J′(x) functions"), Pitzer gave only a table of discrete values of these functions (reported in its original Table II). It is clear that the limited numbers of the calculated values of "J′ functions" are not sufficient for practical evaluation of the corresponding mixed parameters in unsymmetrical mixing of electrolyte systems at any desired ionic strength. Effectively, a survey of the related literature shows that many authors neglect the contribution of the higher order electrostatic terms in their calculations, while, only a few of them resort to the numerical calculation using computer. In this communication, after a brief review of the subject, the corresponding explicit forms of the "derivative Pitzer's J′(x) functions" in series forms are derived and compared to the original numerical Pitzer data. Using these equations along with an appropriate simple routine software PC program (e.g. Excel); it would be easy to evaluate the contribution of the effect of the higher order electrostatic terms in the thermodynamic investigation of the electrolyte systems.