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°.