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.