It forms at the anode when brine is electrolyzed.
This species is disproportionated by reacting with sodium hydroxide in the Hooker process. In theclassic example of the reactivity-selectivity principle, this molecule abstracts any hydrogen from ahydrocarbon. Addition of this species to carbon monoxide makes phosgene. This oxidizing agent forms when acid reacts with bleach. Homolytic bond cleavage of this molecule is the first step in the Born-Haber cycle for (*) table salt. It forms at the anode when brine is electrolyzed. Before Zyklon B and mustard gas, Fritz Haber weaponized this molecule for the Germans in World War I. For 10 points, name this molecule which is added to water to sterilize it, a diatomic yellow poisonous gas composed of the second halogen. 
This species is disproportionated by reacting with sodium hydroxide in the Hooker process.
chlorine gas [or Cl2 ] 