122 NON-METALS AND THEIE COMBINATIONS. 



explosion, for which reason care must be taken in the preparation 

 and handling of these compounds. 



Chlorine acids. 



Hydrochloric acid, HC1. 



Hypochlorous acid, HC1O. 



Chlorous acid, HC1O 2 . 



Chloric acid, HC1O 3 . 



Perchloric acid, HC1O 4 . 



With the exception of hydrochloric acid, which has been considered, 

 none of the five acids is of practical interest as such, but many of 

 the salts of hypochlorous and chloric acids, known as hypochlorites 

 and chlorates respectively, are of great and general importance. 



Hypochlorous acid, HC1O, may be obtained by the action of 

 chlorine water on mercuric oxide, insoluble mercuric oxychloride 

 being formed also : 



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



Hypochlorous acid is a colorless, monobasic acid possessing strong 

 bleaching properties. 



Hypochlorites are formed by the action of chlorine on the hydrox- 

 ides of potassium, sodium, calcium, etc., at the ordinary temperature : 



2NaOH + 2C1 = NaCl + NaCIO + H 2 0. 



Chloric acid, HC1O 3 , may be obtained from potassium chlorate by 

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

 stance which will decompose, frequently with a violent explosion. 

 Chlorates are generally obtained by the action of chlorine on alkali 

 hydroxides at a temperature of about 100 C. (212 F.) 

 6KOH + 6C1 = 5KC1 + KC1O 3 + 3H 2 O. 



Mixtures of hypochlorites and chlorides are converted into chlo- 

 rates by boiling their solution : 



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







Tests for chlorates and hypochlorites. 



(Potass- chlorate, KC1O 3 , and bleaching powder, Ca2ClO.CaCl 2 , may be used.) 



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. 



