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How is potassium dichromate prepared from chromite are ?

Answer»

Solution :Step -1: Potassium dichromate is prepared by fusion of chromite ore `[FeOCr_(2)O_(3)]` with sodium carbonate with excess of air.
`4FeO.Cr_(2)O_(3)+8Na_(2)CO_(3)+7O_(2)rarr2Fe_(2)O_(3)+8Na_(2)CrO_(4)+8CO_(2)`
Step - 2: The yellow solution of sodium CHROMATE is filtered and acidified with sulphuric acid. Orange solution of sodium dichromate is obtained.
`2Na_(2)CrO_(4)+2H^(+)rarrNa_(2)Cr_(2)O_(7)+H_(2)O+2Na^(+)`
Step - 3: The sodium dichromate solution is treated with potassium chloride solution to GET potassium dichromate.
`Na_(2)Cr_(2)O_(7)+2KClrarrK_(2)Cr_(2)O_(7)+2NaCl`
Orange crystals of potassium dichromate crystalises out.


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