Preliminary Tests

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Borax bead test is used to detect:

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The **Borax Bead Test** is a preliminary dry test used to identify certain metal cations based on the color of the bead formed.
1. **Bead Formation**: When Borax ($Na_2B_4O_7 \cdot 10H_2O$) is heated on a platinum wire loop, it swells and then shrinks into a transparent, glassy bead of **Sodium metaborate ($NaBO_2$)** and **Boric anhydride ($B_2O_3$)**.
2. **Reaction**: The bead is touched to the salt and heated again. The metal oxide reacts with $B_2O_3$ to form colored **Metal Metaborates**.
- Examples: **Copper** (blue-green), **Cobalt** (deep blue), **Chromium** (green), **Manganese** (violet/pink).

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Preliminary Tests

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