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JAMB Chemistry 1991 Question 23

Question 23

Electrolysis

If a current of 1.5 A is passed for 4.00 hours through a molten tin salt and 13.3 g of tin is deposited, what is the oxidation state of the metal in the salt? [Sn = 118.7, F = 96500 C mol−1].

  1. A.1
  2. B.2
  3. C.3
  4. D.4
Show the answer and explanation

Answer: B (2)

Explanation

Charge = 1.5 × 4 × 3600 = 21 600 C = 0.224 F. Moles of tin = 13.3 ÷ 118.7 = 0.112. Faradays per mole = 0.224 ÷ 0.112 = 2, so the tin is +2.