The Sublimation Pressure and Standard Enthalpy of Sublimation of Bismuth Triiodide

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J. Korean Ceram. Soc. > Volume 27(7); 1990 > Article

Journal of the Korean Ceramic Society 1990;27(7): 943.

$BiI_3$에 대한 승화압과 승화 표준 엔탈피

김준학

호주 NSW대학교 재료과학공학과

The Sublimation Pressure and Standard Enthalpy of Sublimation of Bismuth Triiodide

ABSTRACT

Steady-state sublimation vapour pressures of anhydrous bismuth triiodide have been measured by the continuous gravimetric Kundsen-effusion method from 430.0 to 558.9 K and equilibrium sublimation pressures were obtained from the steady-state data. Condensation coefficients and their temperature dependence have been derived from the effusiion measurement. Condensation coefficients ranged from 0.159 to 0.048(475 to 500K), the activation enthalpy and entropy for condensation have been obtained as -93.38kTmol-1 and -212.70JK-1mol-1. The standard sublimation enthalpy changes derived by both second(modified sigma function) and third(average enthalpy method) law methods were 138.261$pm$0.023, 138.74$pm$0.002kJmol-1 respectively. The standard sublimation entropy change derived by modified sigma function was 191.98$pm$0.047 JK-1mol-1. The reliable standard sublimation enthalpy change based on a correlation of ΔgcrHom(298.15K) and ΔgcrSom(298.15K), a recommended p(T) equation has been obtained for BiI3(cr) ; 1g(p/Pa)=-C/(T/K)＋5.0711g(T/K)-2.838$times$10-3(T/K)-7.758$times$103(K/T)2＋1.4519 where p is in Pa, T in Kelvin, ΔgcrHom(298.15K) in kJmol-1 and C=(ΔgcrHom(298.15K)-8.7358)/1.9146$times$10-2.