The Planetary Chemistry Laboratory at Washington University in Saint Louis

October 29, 2009


Filed under: — Hugh @ 13:48

CONDOR – Applications

NO Produced by Heating Air

Below is a comparison of the measured and calculated amounts (expressed as a percentage by volume) of NO produced by heating air to high temperatures. The experiments were done by Nernst (1906 Z. Anorg. Chem. 49, 213) and by Briner, Boner and Rothen (1926 J. Chim. Phys. 23, 788).

Reference Temperature (K) vol. % NO
Nernst 1877 0.42
Briner et al. 1873 0.79
CONDOR code 1877 0.56

The calculated NO abundance from the CONDOR code is intermediate between the two observed values and is almost exactly equal to the arithmetic mean of the two observations. For reference, the thermochemical data for NO used in the CONDOR code are based on the enthalpy of formation from the constituent elements at 298.15 K and the thermal functions for NO gas. The former is from calorimetry and the latter are calculated from spectroscopic data for NO using statistical mechanics. The two data sets used in this comparison are not used for computing the NO thermodynamic data. The disagreement between the CONDOR result and either of the two obervations corresponds to a very small difference in the Gibb free energy of formation of NO. This is shown below:

Reference DGยบ (298.15 K) in J/mole
Nernst 87,240
Briner et al. 85,770
CONDOR code 86,600

Equilibrium Between SO2, O2 and SO3

Bodenstein and Pohl (1905 Z. Elektrochem. 11, 373) studied the equilibrium between SO2, O2, and SO3 at 1000 K and one atmosphere total pressure. Some of their data are given below and compared to calculated results from the CONDOR code.

vol. % O2 vol. % SO3 vol. % SO2
Bodenstein and Pohl 0.402 0.325 0.273
CONDOR code 0.404 0.318 0.278

Gas Sample from a Steel Furnace

Darken and Gurry (1953 Physics and Chemistry of Metals, McGraw-Hill, New York, pp. 217-218) give the composition in volume % of a gas sample taken from a heat-treating furnace for steel. They state that the observed gas composition equilibrated at 922 K and one atmosphere pressure. Below, the observed composition is compared to the calculated equilibrium abundances (rounded to the nearest volume %) from the CONDOR code.

CO CO2 H2 H2O CH4 Total
Darken and Gurry 30 5 55 3 7 100
CONDOR code 25 8 46 7 14 100

Water Gas Reaction

Compositions (in volume %) for equilibrated gas mixtures from the water gas reaction (CO2 + H2 = CO + H2O) at 1259 K and one atmosphere are given below (Haber 1908, Thermodynamics of Technical Gas Reactions, Longmans, Green & Co., London), along with a comparison of the calculated equilibrium abundances (also in volume %) from the CONDOR code.

Haber 0.69 9.4 9.4 80.5
CONDOR code 0.69 9.40 9.42 80.49

H2S + CO2 = H2O + OCS

Terres and Wesemann (1932 Angew. Chem. 45, 795-802) studied the equilibrium H2S + CO2 = H2O + OCS at 623-873 K and one atmosphere total pressure. Some of their data at 623 K are reproduced below along with the calculated equilibrium abundances from the CONDOR code. The gas abundances are given in volume %.

Terres and Wesemann 2.72 47.50 47.00 2.80
CONDOR code 2.66 47.31 46.99 2.81

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