LAUSR

Abstract Thermodynamic properties of bismuth chalcoiodides were determined experimentally by means of the electromotive force method (EMF) measurements of the (-) Bi (solid) / ionic liquid, Bi 3+ / (Bi in alloy) (solid) (+) concentration cells in the temperature range 300-390 K (sulfide system) and 300-450 K (selenide and telluride systems). Ionic liquid - morpholinium formate with addition 0.5 mol% anhydrous BiCl 3 was used as an electrolyte. The equilibrium alloys from the different three-phase regions of the corresponding systems were exploited as an anode. The EMF measurements made it possible to calculate the partial molar functions of bismuth in alloys from some three-phase regions. Potential forming reactions were determined based on the solid-phase equilibrium diagrams of the Bi-X-I systems. The standard thermodynamic functions of formation and standard entropies of the BiSI, Bi 19 S 27 I 3 , BiSeI, BiTeI, Bi 2 TeI, and Bi 4 TeI 1.25 ternary compounds were calculated. The standard thermodynamic functions of BiI 3 ,as well as standard entropies of chalcogens, were used to the calculations. A good correspondence between experimental results and the literary data are shown.