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Electrochemistry question

2015 · Shift 0 · Q7
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Electrochemistry question

2015 · Shift 0 · Q7

JEE MainChemistryElectrochemistryMCQ+4 / −1
Two Faraday of electricity is passed through a solution of CuSO4CuSO_4CuSO4​. The mass of copper deposited at the cathode is: (at. mass of Cu = 63.5 amu)
  1. A
    63.5 g
  2. B
    2 g
  3. C
    127 g
  4. D
    0 g
View written solutionFree

Correct answer: A

  1. Write the cathode reaction

    In aqueous CuSO4CuSO_4CuSO4​, copper ions are reduced at the cathode: Cu2++2e−→CuCu^{2+} + 2e^- \rightarrow CuCu2++2e−→Cu

  2. Use Faraday's law of electrolysis

    • 111 mole of CuCuCu requires 222 moles of electrons.
    • 111 Faraday =1= 1=1 mole of electrons.

    Therefore:

    • 222 Faraday =2= 2=2 moles of electrons
    • This will deposit: 2 mol e−2 mol e−/1 mol Cu=1 mol Cu\frac{2\text{ mol } e^-}{2\text{ mol } e^- / 1\text{ mol Cu}} = 1\text{ mol Cu}2 mol e−/1 mol Cu2 mol e−​=1 mol Cu
  3. Convert moles of copper to mass

    Atomic mass of copper =63.5 g/mol= 63.5\,g/mol=63.5g/mol

    So deposited mass: 1×63.5=63.5 g1 \times 63.5 = 63.5\,g1×63.5=63.5g

  4. Match with the options

    The correct option is: A: 63.5 g\boxed{A:\ 63.5\,g}A: 63.5g​

  5. Compare with stored correct answer

    Stored correct answer: AAA

    My derived answer is also AAA, so they agree.

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