3.1 Borax

1.1 Physical Properties
1.2 Chemical Properties

3.1 Borax
3.2 Orthoboric acid ($H_3BO_3$)
3.3 Diborane ($B_2H_6$)
3.4 Boron Halides $(BX_3)$

5.1 Physical Properties
5.2 Chemical Properties

6.1 Diamond
6.2 Graphite
6.3 Fullerene

7.1 Carbon Monoxide $(CO)$
7.2 Carbon Dioxide $(CO_2)$

8.1 Compounds of Silicon

9.1 Important compounds of Nitrogen

10.1 Nitrogen Oxide $N_2O$ or Laughing gas (Neutral)
10.2 Nitric Oxide $NO$ (Neutral)
10.3 Nitrogen trioxide $N_2O_3$
10.4 Nitrogen dioxide or Di-nitrogen tetroxide $NO_2$ or $N_2O$
10.5 Nitrogen pentaoxide $N_2O_5$

11.1 Nitric acid $HNO_3$
11.2 Oxidation of Metalloid and Inorganic compounds by Nitric acid
11.3 Action of Metals & Proteins

13.1 Ozone

14.1 Oxides of Sulphur
14.2 Oxyacids of Sulphur

It is a white crystalline solid of formula $Na_2B_4O_7.10H_2O$. It contains the tetranuclear units $[B_4O_5(OH)_4]^{2-}$ and correct formula is $Na_2[B_4O_5(OH)_4].8H_2O$.

1. Borax dissolves in water to give an alkaline solution. $$N{a_2}{B_4}{O_7} + 7{H_2}O \to 2NaOH + 4{H_3}B{O_3}\left( {{\text{Orthoboric acid}}} \right)$$

2. Borax Bead Test: On heating, borax first loses water molecules and swells up. On further heating it turns into a transparent liquid, which solidifies into glass like material known as borax bead.

$$N{a_2}{B_4}{O_7}.10{H_2}O\mathop \to \limits^\Delta N{a_2}{B_4}{O_7}\left( {{\text{Sodium metaborate}}} \right)\mathop \to \limits^{740^\circ C} 2NaB{O_2} + {B_2}{O_3}\left( {{\text{Boric anhydride}}} \right)$$

When hot glassy mass is brought in contact with coloured salt and heated again in the flame, $B_2O_3$ displaces. The volatile oxides combines with basic oxides to form metaborates. Metaborates of basic radicals have characteristic colours in hot oxidizing/reducing and cold oxidizing/reducing flames.

$$CuS{O_4} + {B_2}{O_3} \to CuO.{B_2}{O_3}\left( {{\text{Blue}}} \right) + S{O_3}$$