What happens when barium reacts with oxygen

Barium oxide

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Barium oxide is the oxide of the alkaline earth metal barium. It has the formula BaO.


Barium oxide is a colorless solid that melts at 1918 ° C. It reacts with water to form barium hydroxide, generating vigorous heat.

$ \ mathrm {BaO + \ H_2O \ longrightarrow \ Ba (OH) _2} $


Technically, it is produced by heating a carbon-barium carbonate mixture to around 1030 ° C, in the laboratory also by annealing barium nitrate.[1]

$ \ mathrm {BaCO_3 \ longrightarrow \ BaO + \ CO_2} $


Barium oxide is used as an absorbent for carbon dioxide and as a drying agent as well as for the production of barium peroxide, barium hydroxide, organic barium salts, special glasses and oxide cathodes.

In an oxygen atmosphere, barium oxide undergoes an equilibrium reaction to form barium peroxide BaO2.

$ \ mathrm {2 \ BaO + \ O_2 \ rightleftharpoons 2 \ BaO_2} $

Between 500 and 600 ° C, BaO reacts to form barium peroxide. Above 600 ° C, the oxygen bound in the peroxide is released again. BaO must therefore not be heated too much, since the equilibrium reaction to the barium peroxide is associated with the release of heat (exothermic reaction) and a change in volume, the equilibrium shifts to the left with increasing temperature. You can therefore bind oxygen at a low temperature and release it again at a higher temperature.

Individual evidence

  1. 1,01,1Helmut Sitzmann, in: Roempp Online - Version 3.5, 2009, Georg Thieme Verlag, Stuttgart.
  2. 2,02,12,22,32,4data sheet Barium oxide at AlfaAesar, accessed January 29, 2010 (JavaScript required).
  3. 3,03,1 Not explicitly listed in EU Regulation (EC) 1272/2008 (CLP), but falls under the collective term there with the specified labeling "Barium salts";Entry from the CLP regulation on barium salts in the GESTIS substance database of the IFA, accessed on April 8, 2012 (JavaScript required) Reference error: Invalid tag. The name "CLP_82780" was defined several times with different content.
  4. ↑ data sheet Barium oxide from Sigma-Aldrich, accessed March 9, 2011.
  5. ↑ Since December 1, 2012, only GHS hazardous substance labeling has been permitted for substances. The R-phrases of this substance may still be used to classify preparations until June 1, 2015, after which the EU hazardous substance labeling is of purely historical interest.
  6. ↑ PAETEC Formula Collection Edition 2003, p. 116.