Chlorine gas, chemical formula Cl₂. At room temperature and pressure is yellow-green, toxic gas with strong irritant odor, density is larger than air, soluble in water, easy to compress, can be liquefied into golden yellow liquid chlorine, is one of the main products of chlor-alkali industry, can be used as a strong oxidant. Chlorine gas mixed with hydrogen with a volume fraction of more than 5% May be explosive when exposed to bright light. Chlorine gas can be substituted and added with organic and inorganic substances to produce a variety of chlorides. Chlorine was used as a bleaching agent in paper and textile industries in the early days.

Main purpose

(1) Disinfection of tap water commonly used chlorine disinfection, 1L water into about 0.002g of chlorine, disinfection principle is its reaction with water to generate hypochlorous acid, its strong oxidation performance to kill bacteria in the water. The reason why hypochlorous acid is not directly used for disinfection of tap water is that hypochlorous acid is easy to decompose and difficult to preserve, with high cost and high toxicity. Therefore, disinfection with chlorine gas can make the dissolution, decomposition and synthesis of hypochlorous acid in water reach a balance, with appropriate concentration and less residual toxicity in water.

(2) Make hydrochloric acid

(3) Industrial use for making bleaching powder or bleaching powder.

(4) Produce a variety of pesticides (such as hexachlorocyclohexane, commonly known as 666).

(5) Make chloroform, carbon tetrachloride and other organic solvents

(6) Plastic (such as polyvinyl chloride plastic) and other Cl₂ can be used to prepare a variety of disinfectants, including Cl disinfectant ClO₂,NaClO,Ca(ClO)₂.

(7)  Often used to oxidize FeCl₂ to FeCl₃

(8)  Industrial use for seawater bromine extraction (Cl₂+2NaBr==Br₂+2NaCl)

Bleaching and bleaching

There are many bleaching substances made of Cl2, and two kinds are involved in general life, NaClO and Ca(ClO)₂

Generally speaking, the disinfectant is NaClO, which is liquid because it is stable. It is generally prepared by injecting chlorine gas into sodium hydroxide. But its price is higher, industrial bleaching is not used, common in 84.

Disinfection powder is Ca(ClO)₂, because it is not stable enough is generally solid, is chlorine gas into the lime milk, low price, used for industrial bleaching, the use method is to add water to dissolve the effective ingredient is calcium hypochlorite, thus bleaching.

When storing the above bleach, pay attention to seal dry and avoid direct sunlight. Because hypochlorite in the air will react with carbon dioxide, water, to produce hypochlorous acid, hypochlorous acid in the light of decomposition, resulting in the failure of bleach.

Safe storage and transportation

Liquid chlorine is prone to the following problems in production, storage and transportation:

(1) The mixture of chlorine, hydrogen and air in the liquefied exhaust gas explodes;

(2) The residual organic impurities in the packaging container react with chlorine gas and explode;

(3) Ammonium salt in water and salt aqueous solution into the liquefication system, will make the accumulation of nitrogen trichloride in liquid chlorine and cause explosion.