The difficulties encountered in the determination of equilibrium constants in systems with small, not directly rneasureable free ligand concentrations are discussed. These difficulties are illustrated using the determination of the formation constants of the Tl(III)-Cl- system as a specific example. Four methods are used and evaluated in this study. They are (1) the corresponding solutions method, (2) the method of Fronaeus, (3) the solubility of AgCl in Tl(III) solution method and (4) the method of Hugus. A discussion and derivation of each of these methods is given. The first three methods given and free ligand concentration data from which formation constants are calculated. The last method gives formation constants directly. Only the method of Fronaeus was capable of yielding data from which all four constants of this system can be calculated. The corresponding solutions method can be used only for the determination of β3 and β4, and the solubility measurement method can be used to calculate only β1. The method of Hugus fails completely in the Tl(III)-Cl- system. Using the data obtained from the method of Fronaeus, formation constants are calculated by solving the n̄ equation directly as well as by a graphical technique. The formation constants found in this study are given in the following table.
College and Department
Chemistry and Biochemistry
BYU ScholarsArchive Citation
Dalley, Nelson Kent, "Evaluation of methods used in the determination of stability constants of the thallium (III)-chloride system at twenty-five degrees" (1964). Theses and Dissertations. 8195.
Thallium, Solution (Chemistry)