title: Gas evolution reaction
text: # Gas evolution reaction
  
  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.
  
      ${\ce {Zn + H_2SO_4 (dil) -> ZnSO_4 + H_2 ^}}$
      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):
  
      ${\ce {2HCl + F_2 -> 2HF + Cl_2 ^}}$
  