What is Cl2? Important knowledge about Cl2.

Definition of Cl₂: Cl₂, also known as chlorine, is a chemical substance of the nonmetal type. Its English name is Chlorine. It is represented by the symbol Cl₂ because each molecule of chlorine consists of 2 chlorine atoms. The atomic weight of chlorine is 35.5 u and the atomic mass is 70.9 g/mol. The chlorine molecule is composed of two chlorine atoms bonded together by a single bond. When forming an ion, chlorine generally gains an extra electron to become the chloride ion Cl-.

Properties of Cl₂: Chlorine in the gas state, is greenish-yellow. The smell of chlorine is quite distinctive, pungent and toxic, similar to the smell of bleach. The chemical properties of Chlorine are very diverse, it can react with many different substances.

Common Chemical Equations with Cl₂: Chlorine can react with metals, acids, nonmetals, and salts. Examples in redox reactions are:

• 2Na + Cl₂ -> 2NaCl
• 2Fe + 3Cl₂ -> 2FeCl₃
• H₂ + Cl₂ -> 2HCl
• 2H₂S + Cl₂ -> 2HCl + S₂
• NaBr + Cl₂ -> NaCl + Br₂

Synthesis of Cl₂:
4.1 Laboratory synthesis: In the lab, chlorine is typically produced in a reaction between manganese dioxide and hydrochloric acid:

• MnO₂ + 4HCl -> MnCl₂ + 2H₂O + Cl₂
  4.2 Industrial synthesis: On an industrial scale, chlorine is usually produced by the electrolysis of a NaCl solution.