Thermodynamic properties of thulium and ytterbium in molten caesium chloride

Abstract This work presents the results of a study of the Tm 3+ /Tm 2+ and Yb 3+ /Yb 2+ couple redox potentials vs. Cl − /Cl 2 reference electrode at the temperature range (973 to 1123) K in molten CsCl by direct potentiometric method. Initial concentrations of TmCl 3 and YbCl 3 in solvents did not exceed 5.0 mol%. Basic thermodynamic properties of the reactions TmCl 2(l)  + 1/2 Cl 2(g)  ⇔ TmCl 3(l) and YbCl 2(l)  + 1/2 Cl 2(g)  ⇔ YbCl 3(l) were calculated using the temperature dependencies of apparent standard potentials of the couples E Tm 3 + / Tm 2 + ∗ and E Yb 3 + / Yb 2 + ∗ .