Electrolysis (2023 VCE)

1. Purified copper contains at least 99.8% copper. Purified copper is used in electronic devices because it is a good electrical conductor and resists corrosion.
Purified copper is produced from impure copper by electrolysis. The electrolysis cell is shown in the diagram below. The impure copper contains 99% copper. The remainder of the impure copper consists of
• zinc, Zn
• lead, Pb
• gold, Au.

Use your understanding of electrochemistry to discuss how electrolysis is used to purify copper using the cell above. In your response
• provide a definition of electrolysis
• explain what happens to the Au, Zn and Pb with reference to the electrochemical series. 5 marks
Solution

Faraday’s First Law of Electrolysis
It states, "During electrolysis, the amount of chemical reaction which occurs at any electrode under the influence of electrical energy is proportional to the quantity of electricity passed through the electrolyte."

b. Explain how the Faraday constant, F, together with Faraday’s first law of electrolysis, can be used to find the amount of bromine, Br2 , produced when molten potassium bromide, KBr(l), is electrolysed. 3 marks

Solution