how will you prepare borax from colemanite and boric acid
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Borax contains the tetranuclear unit i.e. [B4O5(OH)4]2– . The correct formula is Na2[B4O5(OH)4].8H2O
2) From Colemanite
The mineral colemanite is finely powdered and is boiled with sodium carbonate solution.
Ca2B6O11 + 2 Na2CO3 ——–> Na2B4O7 + 2 NaBO2 + 2 CaCO3 ↓
The precipitate of calcium carbonate thus formed is removed by filtration. The filtrate is concentrated and cooled when crystals of borax separate out. Sodium metaborate present in the mother liquor can be converted into borax by passing a current of carbon dioxide through it.
3) From boric acid
Borax can also be prepared in small amounts by neutralising boric acid with sodium carbonate.
On cooling crystal of borax i.e. Na2B4O7.10H2O separate out.
2) From Colemanite
The mineral colemanite is finely powdered and is boiled with sodium carbonate solution.
Ca2B6O11 + 2 Na2CO3 ——–> Na2B4O7 + 2 NaBO2 + 2 CaCO3 ↓
The precipitate of calcium carbonate thus formed is removed by filtration. The filtrate is concentrated and cooled when crystals of borax separate out. Sodium metaborate present in the mother liquor can be converted into borax by passing a current of carbon dioxide through it.
3) From boric acid
Borax can also be prepared in small amounts by neutralising boric acid with sodium carbonate.
On cooling crystal of borax i.e. Na2B4O7.10H2O separate out.
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