Borax - Preparation, Properties, Uses of Borax | Study Material, Lecturing Notes, Assignment, Reference, Wiki description explanation, brief detail |

Chapter: 12th Chemistry : p-Block Elements-I

Borax

Chemistry : p-Block Elements-I: Borax: Preparation of Borax, Properties of Borax, Uses of Borax

Borax [Na2B4O7.10H2O]:


Preparation:

Borax is a sodium salt of tetraboric acid. It is obtained from colemanite ore by boiling its solution with sodium carbonate.


Borax is normally formulated as Na2B4O7.10H2O. But it contains, tetranuclear units [B4O5. (OH)4]2-. This form is known as prismatic form. Borax also exists two other forms namely, jeweller or octahderal borax (Na2B4O7.5H2O) and borax glass (Na2B4O7).


Properties

Borax is basic in nature and its solution in hot-water is alkaline as it dissociates into boric acid and sodium hydroxide.

Na2B4O7 + 7H2O → 4H3BO3 + 2NaOH

On heating it forms a transparent borax beads.


Borax reacts with acids to form sparingly soluble boric acid.

Na2B4O7 + 2HCl + 7H2O → 4H3BO3 + 2NaCl

Na2B4O7 + H2SO4 + 5H2O  → 4H3BO3 + 2Na2SO4

When treated with ammonium chloride it forms boron nitride.

Na2B4O7 + 2NH4Cl  → 2NaCl + 2BN + B2O3 + 4H2O


Uses of Borax:

·           Borax is used for the identification of coloured metal ions

·           In the manufacture optical and borosilicate glass, enamels and glazes for pottery

·           It is also used as a flux in metallurgy and also acts as a preservative

 

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Study Material, Lecturing Notes, Assignment, Reference, Wiki description explanation, brief detail


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