Chlorine

Products

Chlorine gas is available from specialty retailers as a liquid in compressed gas cylinders.

Structure and properties

Chlorine (Cl, 35.45 u) is a chemical element with atomic number 17 that belongs to the halogens and nonmetals and exists as a yellow-green gas with a strong and irritating odor. Molecularly, it is diatomic (Cl2 resp. Cl-Cl). The boiling point is -34°C. Chlorine is very reactive and a strong oxidizing agent. It has 7 valence electrons and is one electron short of the noble gas configuration. Chlorine reacts with elemental sodium to form sodium chloride (table salt). This is a redox reaction in which sodium acts as the reducing agent and chlorine acts as the oxidizing agent:

It is noteworthy that a reactive metal and a poisonous gas form the relatively harmless crystalline table salt, which is used in cooking. Many other metals form chlorides, for example, iron (ferric chloride), potassium (potassium chloride), aluminum (aluminum chloride) or magnesium (magnesium chloride). With hydrogen, a strongly exothermic chlorine oxyhydrogen reaction occurs after activation:

  • H2 (hydrogen) + Cl2 (chlorine) 2 HCl (hydrogen chloride)

Effects

Chlorine has strong oxidizing, bleaching and disinfecting properties.

Areas of application

  • Component of hydrogen chloride and the hydrochloric acid, for the preparation of active ingredient salts.
  • Chlorine is contained as a substitute in numerous pharmaceutical agents.
  • As a disinfectant (eg chlorine gas, sodium hypochlorite).
  • For chemical syntheses, for example, for chlorinations in organic chemistry.
  • For water treatment.

Adverse effects

Chlorine is toxic and unprotected contact with the gas is life threatening. It can cause severe burns to the skin, mucous membranes, eyes and respiratory tract. As an oxidizing agent, it is also fire-promoting and harmful to the environment. Chlorine gas is heavier than air and can accumulate on the ground. It has been repeatedly misused as a poison gas in the past.