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Knudsen Effusion Study of the Vaporization of CdO(s)
Author(s) -
TOM COYLE R.,
LEWIS GORDON
Publication year - 1974
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1974.tb11421.x
Subject(s) - knudsen number , vaporization , body orifice , effusion , chemistry , analytical chemistry (journal) , thermodynamics , activation energy , mineralogy , physics , chromatography , organic chemistry , ecology , biology
Knudsen effusion studies were conducted on CdO(s) in fused‐SiO 2 Knudsen cells from 889 to 1110 K. The orifice size was varied; the largest cell orifice yielded a calculated pressure significantly lower than could be accounted for by experimental error. Average‐slope‐ and average‐free‐energy‐function‐based values of Δ H c 298 were 86.9 ± 1.1 and 88.8 ± 0.5 kcal/mol, respectively. The data from the present work were combined with those of previous investigators using a method discussed by McCreary and Thorn; a Δ H c 298 of 88.2 ± 0.2 kcal/mol was obtained. Using this combined value for Δ H c 298 and ΔS c 298 = 51.40 ± 0.1 eu (obtained from the literature), the equilibrium constant for the reaction CdO(s)= Cd(g)+ 1/2 O 2 (g) at 900 to 1380 K was calculated to be log K = 10.6‐18,800(I/T).