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When copper sulfate solution is electrolysed using copper electrodes, the mass of each electrode changes - Edexcel - GCSE Chemistry Combined Science - Question 3 - 2022 - Paper 1
Question 3
When copper sulfate solution is electrolysed using copper electrodes, the mass of each electrode changes. (a) Draw a labelled diagram to show the apparatus that can... show full transcript
Worked Solution & Example Answer:When copper sulfate solution is electrolysed using copper electrodes, the mass of each electrode changes - Edexcel - GCSE Chemistry Combined Science - Question 3 - 2022 - Paper 1
Step 1
Draw a labelled diagram to show the apparatus that can be used to electrolyse copper sulfate solution using copper electrodes.
Answer
To draw the apparatus, follow these steps:
- Beaker: Draw a beaker as the container for the copper sulfate solution.
- Electrodes: Show two copper electrodes, one for the anode and one for the cathode, submerged in the solution.
- Power Supply: Indicate a power supply connected to the electrodes to provide a current.
- Label: Clearly label all components including the beaker, electrodes, and power supply for clarity.
Step 2
Explain what should be done to the copper electrodes before their masses are determined.
Answer
Before measuring the mass of the copper electrodes, they should be cleaned thoroughly to ensure accurate readings. This can be done by:
- Cleaning: Scrub the electrodes using a suitable solvent (like ethanol or distilled water) to remove any surface oxides or impurities that might affect the mass.
- Drying: Allow the electrodes to dry completely before weighing to ensure that no excess moisture affects the mass readings.
Step 3
Figure 2 shows the results obtained from an electrolysis experiment when copper sulfate solution was electrolysed for 10 minutes.
Answer
To analyze the results shown in Figure 2:
- Initial Mass: Note the mass of the anode (6.43 g) and cathode (6.17 g) before electrolysis.
- Final Mass: After electrolysis, the anode had a mass of 5.62 g and the cathode 6.95 g.
- Change in Mass: The mass at the anode decreased due to oxidation (loss of copper), while the cathode's mass increased due to reduction (gain of copper). This confirms the transfer of copper ions from anode to cathode during the process.