1.

When chromite ore `FeCr_(2)O_(4)` is fused with NaOH in presence of air, a yellow coloured compound ( A) is obtained which on acidification with dilute sulphuric acid gives a compound ( B). Compound (B) on reaction with KCl forms an orange coloured crystalline compound (C ) (i) Write the formulae of the compounds (A) , (B) and (C ) (ii) Write one use of compound (C ) .

Answer» (i) `4FeCr_(2)O_(4) + 16 NaOH + 7O_(2) rarr underset("(A)(Sodium chromate")(8 Na_(2)CrO_(4))+ 2Fe_(2)O_(3)+ 8 H_(2)O`
`2Na_(2)CrO_(4) + H_(2)SO_(4) rarr underset("(B) Sodium dichromate")(Na_(2) Cr_(2)O_(7)) + Na_(2)SO_(4)+ H_(2)O`
`Na_(2)Cr_(2)O_(7) + 2KCl rarr underset("(C ) Potassium dichromate")( K_(2)Cr_(2) O_(7)) + 2NaCl`
(ii) Potassium dichromate is used as a powerful oxidizing agent in industries and in the tanning of leather.


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