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JAMB Chemistry 1987 Question 23

Question 23

Electrolysis

What mass of magnesium would be obtained by passing a current of 2 amperes for 2 hrs. 30 mins through molten magnesium chloride? [1 Faraday = 96500 coulombs, Mg = 24]

  1. A.1.12 g
  2. B.2.00 g
  3. C.2.24 g
  4. D.4.48 g
Show the answer and explanation

Answer: C (2.24 g)

Explanation

Q = 2 × 9000 s = 18000 C. Mg2+ needs 2 × 96500 C per 24 g, so mass = 24 × 18000/193000 = 2.24 g.