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In an acidic medium, 20 mL of a 0.1 M potassium dichromate ( K ₂ Cr ₂ O ₇ ) solution is used to completely oxidize a 0.5 M ferrous sulphate ( FeSO ₄ ) solution. The volume of the FeSO ₄ solution required for this reaction is mL.

Correct answer

24

Step-by-step solution

In an acidic medium, the reduction of potassium dichromate is given by: Cr ₂ O ₇²⁻ + 14 H ^+ + 6 e ^- 2 Cr ³⁺ + 7 H ₂ O Thus, the n-factor of K ₂ Cr ₂ O ₇ is 6 . The oxidation of ferrous sulphate is: Fe ²⁺ Fe ³⁺ + e ^- Thus, the n-factor of FeSO ₄ is 1 . According to the law of equivalence: Equivalents of K ₂ Cr ₂ O ₇ = Equivalents of FeSO ₄ M₁ V₁ n₁ = M₂ V₂ n₂ 0.1 20 6 = 0.5 V₂ 1 12 = 0.5 V₂ V₂ = 24 mL Answer: 24

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