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Electrochemistry question

2025 · Shift 1 · Q8
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Electrochemistry question

2025 · Shift 1 · Q8

JEE AdvancedChemistryElectrochemistryNumerical+4 / −1
In an electrochemical cell, dichromate ions in aqueous acidic medium are reduced to Cr3+Cr^{3+}Cr3+. The current (in amperes) that flows through the cell for 48.25 minutes to produce 1 mole of Cr3+Cr^{3+}Cr3+ is ‾\underline{\hspace{2cm}}​. Use: 1 Faraday = 96500 C mol−1
Numerical answer
View written solutionFree

Correct answer: 100

  1. Write the reduction half-reaction

In acidic medium, dichromate is reduced as:

Cr2O72−+14H++6e−→2Cr3++7H2OCr_2O_7^{2-} + 14H^+ + 6e^- \rightarrow 2Cr^{3+} + 7H_2OCr2​O72−​+14H++6e−→2Cr3++7H2​O

From this equation:

  • 666 moles of electrons produce 222 moles of Cr3+Cr^{3+}Cr3+
  • Therefore, 111 mole of Cr3+Cr^{3+}Cr3+ requires:

62=3 moles of electrons\frac{6}{2} = 3 \text{ moles of electrons}26​=3 moles of electrons

  1. Calculate total charge required

Since 111 mole of electrons corresponds to 111 Faraday = 96500 C96500\,C96500C,

Q=3×96500=289500 CQ = 3 \times 96500 = 289500\,CQ=3×96500=289500C

  1. Convert time into seconds

Given time = 48.2548.2548.25 minutes

t=48.25×60=2895 st = 48.25 \times 60 = 2895\,st=48.25×60=2895s

  1. Use the relation Q=ItQ = ItQ=It

I=Qt=2895002895I = \frac{Q}{t} = \frac{289500}{2895}I=tQ​=2895289500​

I=100 AI = 100\,AI=100A

  1. Final answer

The current flowing through the cell is:

100\boxed{100}100​

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