866.    ---------------. [FALCKE, V.]  [Equilibrium C+CO₂=2CO.  Thermodynamics of the Blast-Furnace Process.]  Ztschr. Elektrochem., vol. 33, 1927, pp. 1-11; British Chem. Abs., 1927, B, p. 191.

     Values recorded in the literature for the equilibrium constant, k=[CO]²/[CO₂], at various temperatures (523°-1,150°) have been collected and compared by plotting on a log k-T diagram:  Corresponding values for the heat of reaction, q, have been calculated from those of k.  Independent sets of values for k and q have been calculated from specific heat data and figures for the heats of combustion of C and CO.  At a given temperature 2 values of k (calculated), and similarly of q (calculated), are obtained according to whether graphite or amorphous C is regarded as participating in the reaction; but for k (calculated) the difference becomes inappreciable at the higher temperatures.  Above 750° values of k (experimental) agree well among themselves and with the corresponding calculated values, but at lower temperatures they are somewhat irregular.  Comparison of values of q (from experimental k) with those of q (calculated) shows that above about 750° the former fit in with the assumption that graphite participates in the equilibrium, whereas, at lower temperatures they correspond more closely to values for amorphous C.  Values of k (experimental) obtained from equilibria reached from the CO side in the presence of Fe powder diverge notably from those obtained in other ways when the equilibrium temperature is below 750°.  This discrepancy is ascribed to the abnormal condition of the C in the iron; it is markedly reduced if the Fe is previously treated with CO for a long time so that free C may be deposited in it.  In any case, the establishment of equilibrium is undoubtedly slow at the lower temperatures, and is not well-defined.  Measurements of k derived from the composition of blast-furnace gases have also been collected on log k-T diagrams.  They are very irregular at lower temperatures, but correspond approximately with the experimental and calculated values at temperatures above about 750°.  Thus the equilibrium C+CO₂=2CO is only attained in the blast furnace gases at these higher temperatures.