Thursday, September 10, 2020

Borax Preparation

 Borax  [Na2B4O7.10H2O]              

          Borax is a sodium salt of tetraboric acid. Fine powdered colemanite ( Ca2B6O11 ).    Is boiled with sodium carbonate ( washing soda ) solution. The insoluble calcium carbonate is filtered off ( CaCO3 ).  Then it is concentrated and cooled to get the crystals of borax. The sodium metaborate is treated with           CO2  gas which converts into borax.

Ca2B6O11  +  2Na2CO3  ———>  Na2B4O7     +      2NaBO2         +        2CaCO3

Colemanite                                  Borax                 Sodium                     calcium

                                                                            metaborate                carbonate

2NaBO2  +  CO2  ———>  Na2B4O7  +  Na2CO3

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