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A battery is constructed of Cr and Na ₂ Cr ₂ O ₇ . The unbalanced chemical equation when such a battery discharges is following: Na ₂ Cr ₂ O ₇+ Cr + H ⁺ Cr ³⁺+ H ₂ O + Na ⁺ If one Faraday of electricity is passed through the battery during the charging, the number of moles of Cr ³⁺ removed from the solution is

Options

  1. A4 3
  2. B1 3
  3. C3 3
  4. D2 3

Correct answer

C. 3 3

Step-by-step solution

Reduction half reaction : Cr ₂ O ₇²⁻+6 e⁻+14 H ⁺ 2 Cr ³⁺+7 H ₂ O Oxidation half reaction : Cr Cr ³⁺+3 e⁻ Overall reaction : aligned & Cr ₂ O ₇²⁻+ Cr +14 H ⁺+3 e⁻ & 3 Cr ³⁺+7 H ₂ O aligned 3 ~F of electricity =3 moles of Cr ³⁺1 ~F of electricity = 3 3 moles of Cr ³⁺

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