JAMB Chemistry 2019 Objective — Question 1
Question 1 of 40 from the Joint Admissions and Matriculation Board (JAMB) Chemistry 2019 Objective paper, with the correct answer and a full explanation.
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A current was passed into an electrolyte containing copper (II) ions for 11 minutes, 22 seconds, and 60g of copper was deposited. How many grams of gold would be deposited by the same quantity of electricity, if passed through a solution containing gold ions? (Cu=64, Au=197)
- A. 123gCorrect
- B. 100g
- C. 55g
- D. 56.56g
Explanation
n(Cu)=60/64=0.9375mol. Since Cu²⁺ requires 2F and Au³⁺ requires 3F: 0.9375×2 = n(Au)×3 ⇒ n(Au)=0.625mol. Mass of Au = 0.625×197 = 123.1g.
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