104 NON-METALS AND THEIR COMBINATIONS. 



Chlorine acids. 



Hydrochloric acid, HC1. 



Hypochlorous acid, HC1O. 



Chlorous acid, HC1O 2 . 



Chloric acid, HC10 3 . 



Perchloric acid, HC10 4 . 



With the exception of hydrochloric acid, which has been con- 

 sidered, none of these five acids is of practical interest as such, 

 but many of the salts of hypochlorous and chloric acid, known 

 as hypochlorites and chlorates respectively, are of great arid 

 general importance. 



Hypochlorous acid, HC10, may be obtained by the action of 

 chlorine water on mercuric oxide, insoluble mercuric oxychloride 

 being also formed : 



2HgO + 4C1 + H 2 O = Hg 2 OCl 2 + 2HC1O. 



Hypochlorous acid is a colorless, monobasic acid possessing 

 strong bleaching properties. 



Hypochlorites are formed by the action of chlorine on the 

 hydrates of potassium, sodium, calcium, etc., at the ordinary 

 temperature : 



2NaHO + 2C1 = NaCl + NaCIO -f H 2 0. 



Chloric acid, HC10 3 , may be obtained from potassium chlorate 

 by the action of hydrofluosilicic acid; it is, however, an unstable 

 substance which decomposes frequently with a violent explosion. 



Chlorates are generally obtained by the action of chlorine on 

 alkaline hydrates at a temperature of about 100: 



6KHO + 6C1 = 5KC1 + KC1O 3 -j- 3H 2 O. 



Mixtures of hypochlorites and chlorides are converted into 

 chlorates by boiling their solution : 



3KC1 + 3KC10 = 5KC1 + KC1O 3 . 



Tests for chlorates and hypochlorites. 



1. Chlorates liberate oxygen when heated by themselves. 



2. Chlorates liberate chlorous tetroxide, C1 2 O 4 , a deep yellow 

 explosive gas, on the addition of strong sulphuric acid. 



