Laboratory Activity 1G (Electroplating of Metals by Electrolysis) :
Aim: To study the electroplating of an iron spoon with copper.
Materials: 1.0 mol dm−3 of copper(II) sulphate, CuSO4 solution, iron spoon, copper plate and sandpaper.
Apparatus: Beaker, battery, connecting wires with crocodile clips, ammeter, switch and rheostat.
Procedure:
1. Clean the copper plate and iron spoon with sandpaper.
2. Pour 1.0 mol dm−3 of copper(II) sulphate, CuSO4 solution into a beaker until half full.
3. Connect the iron spoon to the negative terminal of the battery and the copper plate to the positive terminal of the battery using the connecting wires.
4. Dip the iron spoon and copper plate into the 1.0 mol dm−3 of copper(II) sulphate, CuSO4 solution as shown in Figure 1.33.
5. Turn on the switch and adjust the current flow to 0.2 A using the rheostat.
6. Turn off the switch after 30 minutes.
7. Take out the iron spoon from the electrolyte and leave to dry.
8. Record your observation and complete the table below.
Results:
Record all observations in the following table.
Discussion:
1. Based on the half equations that you wrote for the reactions at the anode and cathode:
(a) is electroplating a redox reaction?
(b) explain your answer in 1(a) in terms of electron transfer.
2. Is there any colour change to the copper(II) sulphate, CuSO4 solution?
Explain your answer.
3. A good electroplating occurs if the layer of the plating on the metal is uniform and long lasting. Suggest two ways to achieve good electroplating.
4. Draw a labelled diagram of the set-up of apparatus for an experiment to electroplate an iron ring with nickel metal.
Answer:
1. (a) Yes.
1. (b) Oxidation reaction occurs when copper atoms lose electrons to form Cu2+ ions at the anode (copper) and reduction reaction occurs at the cathode (iron spoon) when Cu2+ ions gain electrons to form copper atoms.
2. The blue colour of copper(II) sulphate solution remains unchanged because the concentration of Cu2+ ions remains unchanged.
The discharge rate of Cu2+ ions at the cathode is the same as the ionisation rate of copper atoms at the anode.
3.
– Rotate the iron spoon during the electroplating process to get a uniformed layer of plating.
– Use a low current during the electroplating process to get a strong layer of coating on the iron spoon.
4.
Aim: To study the electroplating of an iron spoon with copper.
Materials: 1.0 mol dm−3 of copper(II) sulphate, CuSO4 solution, iron spoon, copper plate and sandpaper.
Apparatus: Beaker, battery, connecting wires with crocodile clips, ammeter, switch and rheostat.
Procedure:
1. Clean the copper plate and iron spoon with sandpaper.
2. Pour 1.0 mol dm−3 of copper(II) sulphate, CuSO4 solution into a beaker until half full.
3. Connect the iron spoon to the negative terminal of the battery and the copper plate to the positive terminal of the battery using the connecting wires.
4. Dip the iron spoon and copper plate into the 1.0 mol dm−3 of copper(II) sulphate, CuSO4 solution as shown in Figure 1.33.
5. Turn on the switch and adjust the current flow to 0.2 A using the rheostat.
6. Turn off the switch after 30 minutes.
7. Take out the iron spoon from the electrolyte and leave to dry.
8. Record your observation and complete the table below.
Results:
Record all observations in the following table.
Discussion:
1. Based on the half equations that you wrote for the reactions at the anode and cathode:
(a) is electroplating a redox reaction?
(b) explain your answer in 1(a) in terms of electron transfer.
2. Is there any colour change to the copper(II) sulphate, CuSO4 solution?
Explain your answer.
3. A good electroplating occurs if the layer of the plating on the metal is uniform and long lasting. Suggest two ways to achieve good electroplating.
4. Draw a labelled diagram of the set-up of apparatus for an experiment to electroplate an iron ring with nickel metal.
Answer:
1. (a) Yes.
1. (b) Oxidation reaction occurs when copper atoms lose electrons to form Cu2+ ions at the anode (copper) and reduction reaction occurs at the cathode (iron spoon) when Cu2+ ions gain electrons to form copper atoms.
2. The blue colour of copper(II) sulphate solution remains unchanged because the concentration of Cu2+ ions remains unchanged.
The discharge rate of Cu2+ ions at the cathode is the same as the ionisation rate of copper atoms at the anode.
3.
– Rotate the iron spoon during the electroplating process to get a uniformed layer of plating.
– Use a low current during the electroplating process to get a strong layer of coating on the iron spoon.
4.