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प्रश्न
State the reason for the addition of caustic alkali to bauxite ore during the purification of bauxite.
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उत्तर
Naturally, Bauxite is not soluble in normal solvents. Therefore the addition of caustic alkali to bauxite plays an important role while the extraction of aluminum. Caustic alkali dissolves bauxite forming soluble sodium meta aluminate while impurities remain insoluble and precipitate as red mud.
\[\ce{\underset{\text{(Bauxite)}}{Al2O3}.2H2O + 2NaOH -> \underset{\text{(Sodium meta aluminate)}}{2NaAlO2 + 3H2O}}\]
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