Das Reduktionsgleichgewicht zwischen Metalloxyd und Wasserstoff. I. Mitteilung. Die Messung von CoO + H₂ ⇄ Co + H₂O nach neuem Meßverfahren

Abstract

I. Nach der von den Verfassern erfundenen neuen Messungsmethode wurden die Reduktionsgleichgewichte bei 921°, 821°, 721°, 622°, 522° und 422° untersucht.

Measurements on Galvanic Cells Involving Solid Electrolytes

“…2 shows these values together with values deduced from gas equilibrium measurements by Emmett and Shultz (15), Watanabe ( 16), and Schenck and Wesselkock ( 17) as a Upon combining ~F ~ values for reaction [7] and the water gas equilibrium calculated from data compiled by Coughlin (11), the standard free energy change for the reaction CoO(s) + H~(g) = Co(s) + H~O(g) [8] has been calculated. Fig 3 shows that these data agree with values calculated from determinations of the H~O/H~ ratio over cobalt and cobalt oxide according to Emmett and Shultz (18) and Kleppa (19) but differ from those reported by Shibata and Mori (20), possibly because of their neglect of thermal diffusion.…”

Standard data for the formation of solid cobaltous oxide

“…Examination of the secondand third-law results for each group of measurements leads us to make a selection. Firstly we have eliminated measurements (2,3,6,10,15,22,24,46) which lead to a second-law standard entropy of formation AS,°(298.15 K) which is more than 4 J mol"1 K'1 greater or less than the value -79.54 J mol"1 K"1 obtained by direct calorimetry. Secondly we have eliminated the measurements (4, 8, 21) which lead to a third-law standard enthalpy of formation AH,"(298.15 K) either abnormally high or low (>-236 000 or <-239 000 J mol"1) and which must include too great a systematic error.…”

“…Direct determination of the standard heat of formation of cobaltous oxide by combustion calorimetry gives the following results: AH,"(298.15 K) = -240400 J mol"1 (31) -240600 ± 800 J mol"1 (32) -238700 ± 1200 J mol"1 (33) Table I summarizes results of experiments on cobaltous oxide, obtained from equilibria of reduction by hydrogen (2)(3)(4)(5)(6)(7)(8)(9)(10)(11), carbon monoxide (12)(13)(14)(15)(16)(17)(18)(19)(20), and methane (21), as well as a direct investigation by mass spectrometry of the CoO-Co-02 equilibria (22). Table II summarizes results of experiments on cobaltous oxide determined from emf measurements with a solid electrolyte cell and various reference electrodes (23)(24)(25)(26)(27)(28)(29)(30)46).…”