Question 97 – Electrolytic processes - Questions

An electronics recycling facility uses industrial electrorefining to recover high-purity copper from scrap copper wiring containing silver ( $A g$ ), gold ( $A u$ ), and zinc ( $Z n$ ) impurities.

In this electrorefining cell:

The anode (+) is a block of the impure scrap copper.
The cathode (-) is a thin sheet of high-purity copper.
The electrolyte is an acidified solution of copper(II) sulfate ( $CuSO_4$ ).

The layout of the apparatus is shown below:

Diagram of a copper electrorefining cell showing the impure copper anode, pure copper cathode, acidified copper(II) sulfate electrolyte, anode sludge containing silver and gold, and zinc ions in solution.

During the continuous operation of the cell, three key observations are recorded:

The mass of the impure copper anode decreases, while the mass of the pure copper cathode increases.
A solid anode sludge containing silver and gold accumulates at the base of the cell directly underneath the anode, but zinc is found dissolved in the electrolyte as $Zn^{2+}(aq)$ ions.
The concentration of copper(II) ions in the electrolyte remains constant.

Electrolytic processes Questions

Practise Edexcel GCSE Chemistry Electrolytic processes with exam-style questions for Foundation and Higher tier. 100 questions, matched to the Edexcel GCSE Chemistry (1CH0) specification and written in Paper 1 and Paper 2 style. Every question includes a full worked solution and mark scheme, so you can see where marks are awarded rather than just whether you got the answer right.

An electronics recycling facility uses industrial electrorefining to recover high-purity copper from scrap copper wiring containing silver ( $A g$ ), gold ( $A u$ ), and zinc ( $Z n$ ) impurities.

In this electrorefining cell:

The anode (+) is a block of the impure scrap copper.
The cathode (-) is a thin sheet of high-purity copper.
The electrolyte is an acidified solution of copper(II) sulfate ( $CuSO_4$ ).

The layout of the apparatus is shown below:

During the continuous operation of the cell, three key observations are recorded:

The mass of the impure copper anode decreases, while the mass of the pure copper cathode increases.
A solid anode sludge containing silver and gold accumulates at the base of the cell directly underneath the anode, but zinc is found dissolved in the electrolyte as $Zn^{2+}(aq)$ ions.
The concentration of copper(II) ions in the electrolyte remains constant.