American Chemical Society, The Journal of Physical Chemistry A, 10(111), p. 1971-1980, 2007
DOI: 10.1021/jp0647380
Wiley-VCH Verlag, ChemInform, 23(38), 2007
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In this paper, we report the results of equilibrium pressure measurements designed to identify the volatile species in the Cr-O-H system and to resolve some of the discrepancies in existing experimental data. In addition, ab initio calculations were performed to lend confidence to a theoretical approach for predicting the thermochemistry of chromium-containing compounds. Equilibrium pressure data for CrO2(OH)2 were measured by the transpiration technique for the reaction 0.5Cr2O3(s) + 0.75O2(g) + H2O(g) = CrO2(OH)2(g) over a temperature range of 573 to 1173 K at 1 bar total pressure. Inductively coupled plasma atomic emission spectroscopy (ICP-AES) was used to analyze the condensate in order to quantify the concentration of Cr-containing volatile species. The resulting experimentally measured thermodynamic functions are compared to those computed using B3LYP density functional theory and the coupled-cluster singles and doubles method with a perturbative correction for connected triple substitutions [CCSD(T)].