Chemistry Of Borax Bead Test

Chemistry Of Borax Bead Test

When borax is heated on loop, it is decomposed to give sodium metaborate and boric oxide and a glassy bead is produced.

                                Na₂B₄O₇            2NaBO₂ + B₂O₃

 When borax compound is heated on this bead, metallic oxides are produced which react with B₂O₃ to give coloured metaborates of metals. Thus metal cations can be identified.

Example           

 With Cu salt CuO is formed which react with B₂O₃ to give Cu(BO₂ )₂ . It shows blue colour in oxidizing flame in cold state and give green colour in hot state.

                                 CuO + B₂O₃                   Cu(BO₂)₂

Cu(BO₂ )₂ is colourless in reducing flame.

Uses

1.      It is used to prepare heat resistant borate glass ( Pyrex Glass ).

2.      It is used in softening of water

3.      It is used in borax bead test for detection of coloured metallic cations.

4.      It is used in metallurgy

5.      It is used as flux in welding and in metallurgy

6.      It is used in making washing powders

7.      It is used in leather industry for tanning and dyeing

8.      It is used in cosmetics, soaps, textiles, paints, medicine, match industry and as a preservative.