دانشگاه آزاد اسلامی واحد تهران جنوب

صفحه اصلی / اولین کنفرانس ملی شیمی، نانو مواد، پلیمر- چالش ها و کاربردها

Thermodynamic properties of (KCl/KSCN/H2O) ternary electrolyte solution by potentiometric method at T=298.15 ± 0.1 K

نویسندگان :

Mohammad Ali Bagherinia¹

1- دانشگاه آزاد اسلامی واحد لاهیجان

کلمات کلیدی :

Thermodynamic properties،KCl،KSCN،Pitzer ion interaction model،Potentiometric method

چکیده :

In this study, the thermodynamic properties of three-component electrolyte solution (KCl + KSCN + H2O) were investigated. For this purpose, first the mean activity coefficients of KCL as the main component were determined by potentiometric method. Potentiometric measurements were performed in a galvanic cell without liquid junction. In this galvanic cell, a polymeric membrane was used as the potassium ion selective electrode and a silver-silver chloride electrode was used as the chloride ion selective electrode. The potentiometric measurements were performed at a temperature of 273.15 ± 0.1 Kelvin in the total ionic strength range of solution between 0.0017 to 2.0000 mol kg-1. The investigated molal ratios of the two salts in the solution were r = "m" _KCl/"m" _"KSCN" = 1.0, 2.5, 5.0, 10.0, 15.0 and pure KCl. The Pitzer ion interaction model and Harned rule were used to study the thermodynamics properties of the solution. From the adaptation of the experimental mean activity coefficients of potassium chloride data in the solution with the Pitzer ion interaction model, the mixing Pitzer parameters (θClSCN, ψKClSCN) were determined. Then these parameters were used to calculate the thermodynamic properties such as the mean activity coefficients of potassium thiocyanate ( γ_(±KSCN) ), the osmotic coefficients of the solvent ( ) and the Gibbs free energies of the solution (GE) based on the Pitzer ion interaction model. The Harand interaction coefficients were obtained using the graph drawing method, too. The results showed that both Pitzer ion interaction model and Harned rule were successful in describing the experimental mean activity coefficients results.