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JAMB Chemistry 2007 Question 19

Question 19

Electrolysis

How long would it take to deposit 0.08g of copper from CuCl2 solution by passing a current of 0.5A? [Cu = 64, F = 96500 C mol−1]

  1. A.6 mins.
  2. B.8 mins.
  3. C.24 mins.
  4. D.48 mins.
Show the answer and explanation

Answer: B (8 mins.)

Explanation

Cu2+ + 2e− → Cu, so 64 g needs 2 × 96500 C. 0.08 g needs 0.08 × 193000/64 = 241.25 C. Time = 241.25 ÷ 0.5 = 482.5 s ≈ 8 minutes.