833.    EMMETT, P. H., AND SCHULTZ, J. F.  Equilibrium in the System:  Carbon Monoxide-Water-Cobalt Oxide-Hydrogen.  Free-Energy Changes for the Reaction CoO+H₂=Co+H₂O and the Reaction Co+1/2 O₂=CoO.  Jour. Am. Chem. Soc., vol. 51, 1929, pp. 3249-3262; Chem. Abs., vol. 24, 1930, p. 774.

      The object was to determine at several temperatures the equilibrium ratio of H₂O:H₂ in the presence of Co.  CoO, reduced by H₂ at the temperature desired, was subjected to various mixtures of H₂+H₂O, and the effluent gases were analyzed for H₂ and H₂O.  A second catalyst was prepared by reducing Co₃O₄ to CoO.  Equilibrium was approached at each temperature from both the H₂O sides.  A modification of the flow system of Pease and Cook, was used.  The ratio H₂O:H₂ at 335° was 85±5; at 450°, 67±1; at 515°, 57.0±0.3; and at 570°, 50.5±0.2.  ∆F°₂₉₈ for the reaction CoO+H₂=H₂O+Co was calculated as –3,678 calories.  ∆H₂₉₈ was calculated as –1,646 calories, as compared with –300 calories calculated from the heats of formation of CoO and H₂O.  X-ray photographs indicated that at 500° H₂O did not form Co₃O₄ from CoO. ∆F°₁₃₇₃ for the formation of CoO from Co and O₂ was calculated at 32,050 calories, and from this, partial pressures of O₂ in equilibrium with CoO and Co at 1,100° was calculated as 0.5X10^-7 mm.  Transformation of hexagonal to cubic Co takes place at 340°-360°.