Explain borax bead test with a suitable example.

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> [!TLDR]
> Fused borax forms a glassy bead of sodium metaborate + boric anhydride which, when heated with a metal salt, forms a coloured metal metaborate — the bead's colour identifies the metal (e.g., blue for Cu2+).
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> **Principle:** Borax, $Na_2B_4O_7\cdot10H_2O$, on strong heating loses its water of crystallisation and then decomposes to give a transparent glassy bead of sodium metaborate and boric anhydride:
> $$Na_2B_4O_7 \xrightarrow{\Delta} 2NaBO_2 + B_2O_3$$
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> **Procedure:** A small amount of the fused borax bead (formed on a platinum/nichrome wire loop) is touched to a little of the coloured metal salt and reheated in the Bunsen flame. $B_2O_3$ reacts with the metal salt to form a **metal metaborate**, which is often distinctly coloured, e.g.:
> $$B_2O_3 + CuSO_4 \longrightarrow Cu(BO_2)_2\ (	ext{blue bead}) + SO_3$$
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> **Example — Copper(II) sulphate:** In the **oxidising flame**, the bead turns **blue** (cupric metaborate, $Cu(BO_2)_2$); in the **reducing flame**, it turns **red/colourless** due to reduction to cuprous metaborate.
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Q.Explain borax bead test with a suitable example.

Concept understanding — Boron — Borax and Boric Acid

Q.Explain borax bead test with a suitable example.

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