A gas evolution reaction is a chemical reaction in which one of the end products is a gas such as oxygen or carbon dioxide. Gas evolution reactions may be carried out in a fume chamber when the gases produced are poisonous when inhaled or explosive.
Examples A replacement reaction concerning zinc metal and dilute sulfuric acid.
Zn + H 2 SO 4 ( dil ) ⟶ ZnSO 4 + H 2 ↑ {\displaystyle {\ce {Zn + H_2SO_4 (dil) -> ZnSO_4 + H_2 ^}}}
In this example, diatomic hydrogen gas is released. Dilute hydrochloric acid can be used in place of dilute sulfuric acid. A replacement reaction where gaseous hydrogen chloride and fluorine gas react to release diatomic chlorine gas (because fluorine is more electronegative):
2 HCl + F 2 ⟶ 2 HF + Cl 2 ↑ {\displaystyle {\ce {2HCl + F_2 -> 2HF + Cl_2 ^}}}
See also Gasogene Kipps apparatus Gas generator Thermal decomposition Oxygen evolution
References