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a) Impure copper is purified by electrolysis using the apparatus shown - Edexcel - GCSE Chemistry - Question 6 - 2015 - Paper 1
Question 6
a) Impure copper is purified by electrolysis using the apparatus shown. 6 V d.c. supply impure copper electrode copper sulfate solution pure copper electrode i)... show full transcript
Worked Solution & Example Answer:a) Impure copper is purified by electrolysis using the apparatus shown - Edexcel - GCSE Chemistry - Question 6 - 2015 - Paper 1
Step 1
Step 2
ii) Describe how each electrode will have changed at the end of the electrolysis process.
Answer
At the anode (impure copper electrode), it will lose mass as copper ions are oxidized and enter the solution. It will become smaller as the copper atoms lose mass.
At the cathode (pure copper electrode), it will gain mass. Copper ions from the solution are reduced and deposited, forming a red-brown layer on the electrode.
Step 3
Step 4
iv) Explain how copper sulfate solution conducts electricity.
Answer
Copper sulfate solution conducts electricity due to the presence of free ions. When an electric current is applied, the copper ions (Cu²⁺) and sulfate ions (SO₄²⁻) move towards the electrodes, allowing the solution to conduct electricity.
Step 5
Explain how these products are formed from the ions in the electrolysis process, indicating how you would identify the products.
Answer
During the electrolysis of sodium sulfate solution, the hydrogen ions (H⁺) move to the cathode where they gain electrons and form hydrogen gas:
At the anode, the hydroxide ions (OH⁻) lose electrons, forming oxygen gas and water:
The hydrogen gas can be identified by its effervescence and characteristic 'popping' sound when ignited, while oxygen can be identified by relighting a glowing splint.