SUBLIMATION STUDY OF BIBR3

Steady-state sublimation vapour pressures of anhydrous bismuth tribrom ide have been measured by the continuous gravimetric Knudsen-effusion method from 369.3 to 478.8 K. Additional effusion measurements have al so been made from 435.4 to 478.6 K by the torsion-effusion method. Bas ed on a correlation of Delta(sub)H(298)(0) and Delta(sub)S(298)(0), a recommended p(T) equation has been obtained for BiBr3(s) alpha-BiBr3: log p = -C alpha/T - 12.294log T+5.79112 x 10(-3) T+47.173 with C alph a=(Delta(sub)H(298)(0)+20.6168)/1.9146 x 10(-2) beta-BiBr3: log p = - C beta/T-23.251log T+1.0492 x 10(-2) T+77.116 with C beta=(Delta(sub)H (298)(0)+46.2642)/1.9146 x 10(-2) where p is in Pa, T in Kelvin, Delta (sub)H(298)(0) in kJ mol(-1). Condensation coefficients and their temp erature dependence have been derived from the effusion measurements.