Chlorine detonating gas

Chlorine detonating gas is a gas mixture of hydrogen and chlorine which, when exposed or thermally activated, reacts like oxyhydrogen in a violent exothermic reaction to form hydrogen chloride ( hydrogen chloride ):

${\displaystyle \mathrm {H_{2}+Cl_{2}\ {\xrightarrow {Licht,W{\ddot {a}}rme}}\ 2\ HCl} }$

The reaction was observed in 1809 by the French chemists Joseph Louis Gay-Lussac and Louis Jacques Thénard .

Walther Nernst and Max Bodenstein clarified the reaction mechanism , a light-induced radical chain reaction . It reads:

${\displaystyle \mathrm {Cl_{2}\ {\xrightarrow {Energie}}\ 2\ Cl{\cdot }\quad (Kettenstart)} }$

${\displaystyle \left.{\begin{matrix}\mathrm {Cl{\cdot }+H_{2}\longrightarrow HCl+H{\cdot }} \\\mathrm {H{\cdot }+Cl_{2}\longrightarrow HCl+Cl{\cdot }} \end{matrix}}\quad \right\rbrace \mathrm {(Kettenfortpflanzung)} }$

${\displaystyle \left.{\begin{matrix}\mathrm {H{\cdot }+Cl{\cdot }\ {\xrightarrow {M}}\ HCl} \\\mathrm {2\ H{\cdot }\ {\xrightarrow {M}}\ H_{2}} \\\mathrm {2\ Cl{\cdot }\ {\xrightarrow {M}}\ Cl_{2}} \end{matrix}}\quad \right\rbrace \mathrm {(Kettenabbruch)} }$

A third collision partner M is necessary for the chain termination reactions in order to dissipate the binding energy. The chain length therefore depends on the pressure and reaches values ​​of 10 ⁶ at normal pressure .

The energy released in the chain reaction leads to an increase in temperature, which initially has little influence on the conversion rate, until finally thermal dissociation leads to a rapid increase in the radical concentration .

Individual evidence

1. ↑ Horst Remane , Wolfgang Girnus , “Milestones of Chemistry 2009”, Nachrichten aus der Chemie 57, January 2009, p. 11.
2. ↑ Erwin Riedel , Christoph Janiak: Inorganic Chemistry / Inorganic Chemistry , de Gruyter, 2011, ISBN 978-3-11-022566-2 , limited preview in the Google book search.