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JAMB Chemistry 1987 Question 21

Question 21

Electrolysis

A quantity of electricity liberates 3.6 g of silver from its salt. What mass of aluminium will be liberated from its salt by the same quantity of electricity? [Al = 27, Ag = 108]

  1. A.2.7 g
  2. B.1.2 g
  3. C.0.9 g
  4. D.0.3 g
Show the answer and explanation

Answer: D (0.3 g)

Explanation

3.6 g Ag is 3.6/108 = 1/30 mol, needing 1/30 F. Al3+ needs 3 F per mole, so 1/90 mol Al forms: 27/90 = 0.3 g.