An effusion study of the disproportionation of titanium tri-iodide

Abstract

The disproportionation of titanium tri-iodide has been studied by measuring the rate of effusion of titanium tetra-iodide in the range 360 °–410 °C with five different orifices. The reaction was characterized as 2 TiI 3 ( s)= TiI 2( s) + TiI 4 ( g) and the measured pressure was found to be markedly dependant on orifice size. An equilibrium pressure equation was derived as log p ( torr) = −5923/ T + 8.04 with mean enthalpy and entropy changes of 113.4 ∓ 1.9 kJ and 98.9 ∓ 10 kJ deg −1 respectively. Using the available data, the heat of formation of titanium tri-iodide is estimated to be Δ H ° 298 TiI 3 (s) = −245 ∓ 25 kJ mole −1.