Question

A mixed oxide of iron and chromium FeOCr2O3 is fused with sodium carbonate in the presence of air to form a
yellow coloured compound (A). On acidification the compound (A) forms an orange coloured compound (B),which is a strong oxidising agent. Identify(i) the compounds (A) and (B)(ii) write balanced chemical equation for each step

Answer 1

Hey !!

A : Na₂CrO₄   B : Na₂Cr₂O₇

4FeCr₂O₄ + 8Na₂CO₃ + 7O₂  -----> 8Na₂CrO₄ + 2Fe₂O₃ + 8CO₂

2Na₂CrO₄ + 2H⁺ -----> Na₂Cr₂O₇ + 2Na⁺ + H₂O

GOOD LUCK !!

Answer 2

Hey dear,

● Answer -
Compound A => Sodium chromate
Compound B => Sodium dichromate

● Explanation -
Iron chromate reacts with sodium carbonate in presence of air to form sodium chromate (A) which is a yellow coloured compound.

4FeO.Cr2O3 + 8Na2CO3 + 7O2 → 8Na2CrO4

Sodium chromate (A) on acidification by conc. sulphuric acid gives sodium dichromate (B) which is a strong oxidizing agent.

2Na2CrO4 + H2SO4 → Na2Cr2O7 + Na2SO4 + H2O

Hope this helped you...