Boudouard equilibrium

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Temperature in ° C CO 2 in% CO in%
450 98 2
600 77 23
700 42 58
800 6th 94
900 3 97
1000 1 99
Boudouard equilibrium at 10 5  Pa
The Boudouard equilibrium at 10 5  Pa is calculated from the free enthalpies of formation.

The Boudouard equilibrium is the equilibrium between carbon dioxide (CO 2 ) and carbon monoxide (CO), named after Octave Leopold Boudouard (1872–1923 ), which is established when reacting with glowing carbon .

The enthalpy of formation of carbon dioxide is −393.5 kJ / mol. During the reduction with carbon, two moles of carbon monoxide are formed ( = −110.5 kJ / mol), the process in the gas phase is strongly endothermic (calculated +172.5 kJ / mol).

Due to the endothermic reaction, high temperatures shift the equilibrium to the product side (CO), an increase in pressure shifts it to the reactant side , as the number of gaseous molecules decreases as a result. (See principle of least compulsion ). At room temperature the rate of conversion becomes immeasurably small: carbon monoxide is metastable.

The reaction is used in the production of generator gas and represents an important sub-process in the smelting of iron ore in the blast furnace .

See also

Web links


  1. David R. Lide: CRC Handbook of Chemistry and Physics . 90th edition. Taylor & Francis, 2009, ISBN 978-1-4200-9084-0 .
  2. Reference data for enthalpies of education can be found in the CRC Handbook of Chemistry and Physics : STANDARD THERMODYNAMIC PROPERTIES OF CHEMICAL SUBSTANCES ( Memento from February 25, 2015 in the Internet Archive ) (Chapter 5.4) as well as Benson's method