passwella.
Menu

JAMB Chemistry 1992 Question 23

Question 23

Electrolysis

Calculate the mass, in kilograms, of magnesium produced by the electrolysis of magnesium (II) chloride in a cell operating for 24 hours at 500 amperes. [1 Faraday = 96,500 C mol−1, Mg = 24].

  1. A.2.7
  2. B.5.4
  3. C.10.8
  4. D.21.7
Show the answer and explanation

Answer: B (5.4)

Explanation

Charge = 500 × 24 × 3600 = 43 200 000 C. Mg2+ needs 2 × 96 500 C per 24 g, so mass = 43 200 000 × 24 ÷ 193 000 ≈ 5372 g ≈ 5.4 kg.