Question

moles of Fe2+ oxidised by one mole of dichromate in acidic medium​

Answer 1

Answer:

2 moles

Answer. Fe2+ in ferrous oxalate is oxidised to Fe3+ by acidified K2Cr2O7. That is, each mole of K2Cr2O7 oxidises 2 moles of ferrous sulphate. Hence, to oxidize 2 moles of FeSO4, only 1 mole of K2Cr2O7 is required.

Explanation:

Answer 2

6 moles of Fe⁺² are oxidised by one mole of dichromate in acidic medium

• Each mole of dichromate ion(Cr₄O₇⁻² ) gives 6 electrons

        Cr₄O₇⁻² + 14H⁺ + 6e⁻ ———— > 2Cr⁺³ + 7H₂O

• One mole of Fe⁺² requires 1 electron for oxidation

        Fe⁺² ———— > Fe⁺³ + e⁻

• Therefore each mole of dichromate ion will oxidize 6 moles of Fe⁺²

The reaction taking place in the process is:

   Cr₄O₇⁻² + 14H⁺ + 6e⁻ ———— > 2Cr⁺³ + 7H₂O

   6Fe⁺² ———— > 6Fe⁺³ + 6e⁻

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   Cr₄O₇⁻² + 6Fe⁺² + 14H⁺ ——— > 2Cr⁺³ + 6Fe⁺³ + 7H₂O