The diagram below shows an electrolytic cell used to electrodeplate an iron rod with COPPER - NSC Physical Sciences - Question 9 - 2018 - Paper 2
Question 9
The diagram below shows an electrolytic cell used to electrodeplate an iron rod with COPPER. Solution X is made up of an unknown NITRATE.
9.1 Solutions, such as sol... show full transcript
Worked Solution & Example Answer:The diagram below shows an electrolytic cell used to electrodeplate an iron rod with COPPER - NSC Physical Sciences - Question 9 - 2018 - Paper 2
Step 1
9.1.1 Write down the general term used to describe these solutions.
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Answer
The general term used to describe these solutions is 'electrolyte'. Electrolytes are substances that, when dissolved in a solvent, increase the solution's ability to conduct electricity.
Step 2
9.1.2 What is the function of these solutions in electrochemical cells?
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The function of these solutions in electrochemical cells is to conduct electricity between the electrodes. They provide the ions necessary for the electrochemical reactions to take place, facilitating the transfer of charge.
Step 3
9.2 Write down the FORMULA of solution X.
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The formula of solution X is likely of the form Cu(NO3)2, as it contains copper ions and nitrate ions.
Step 4
9.3 Which electrode (A or IRON ROD) is the negative electrode? Give a reason for the answer.
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The IRON ROD is the negative electrode in the cell. This is because during the electroplating process, copper ions are reduced at the cathode (the negative electrode) to form copper metal on the iron rod.
Step 5
9.4 Write down the half-reaction that takes place at electrode A.
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The half-reaction that takes place at electrode A (the anode) is:
Cu2++2e−→Cu
This represents the reduction of copper ions to solid copper.
Step 6
9.5.1 Name the TWO metallic ions present in the solution.
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The two metallic ions present in the solution would be Cu²⁺ ions and Ag⁺ ions, from the copper and silver respectively.
Step 7
9.5.2 Refer to the relative strengths of oxidising agents to explain which ONE of the two ions will properly be involved in the plating process.
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In this reaction, the Ag⁺ ions will be more readily reduced compared to Cu²⁺ ions because silver is a stronger oxidizing agent than copper. Thus, Ag⁺ ions will be reduced first, leading to the deposition of silver instead of copper on the surface.
