Faraday’s Second Law of electrolysis states that:
“The mass of an element deposited by one Faraday of electricity is equal to the atomic mass in grams of the element divided by the number of electrons required to discharge one ion of the element.”
When the copper plating on the cathode side increases in mass, it is covered with a bright new coating of copper. We say that it has been electroplated with copper.
Apparatus:
- 75 ml Copper Sulphate solution (0.5m)
Fair test:
To make this a fair test, I will need to:
- Keep the current constant
- Use the same amount of Copper Sulphate
Method:
Experiment 1: Mass and Time
For this experiment:
- Firstly the apparatus is collected and set up
-
Then, pour 75cm3 of the Copper Sulphate solution into a small beaker
- Weigh the two Copper Electrodes, record their masses and place into the beaker containing the Copper Sulphate solution
- The electrodes are then connected to the power pack and ammeter. A steady current should flow (0.5 Amps) and the experiment should be stopped every 5 minutes
- At these times the current should be switched off and both electrodes should be removed from the solution
- The electrodes should then be wiped dry and then weighed
- The electrodes should then be carefully weighed and their masses should be recorded
- This experiment should be done three times
Experiment 2: Mass and Current
For this experiment:
- Firstly the apparatus is collected and set up
-
Then, pour 75cm3 of the Copper Sulphate solution into a small beaker
- Weigh the two Copper Electrodes, record their masses and place into the beaker containing the Copper Sulphate solution
- The electrodes are then connected to the power pack and ammeter. Changing the voltage then chooses the current.
- The and the experiment is stopped every 15 minutes
- At these times the current should be switched off and both electrodes should be removed from the solution
- The electrodes should then be wiped dry and then weighed
- The electrodes should then be carefully weighed and their masses should be recorded
- The experiment should be repeated one more time but with different currents.
Diagram:
Results:
Experiment 1: Result 1
Experiment 1: Result 2
Experiment 1: Result 3
Experiment 2: Result 1
Experiment 2: Result 2
Conclusion:
In this experiment, I found that my prediction was correct because the mass the cathode electrode that the longer the current is left to flow, the more Copper metal is deposited on the cathode. This gives the indication that the longer the experiment lasts, the higher the charge and therefore, the higher the amount of Copper produced.
I am therefore correct in saying that, through this experiment, both of Faraday’s Laws Of electrolysis are correct.
Evaluation:
I feel that this experiment has been very successful. However my results show that it could have been better. The experiment could have been improved if the electrodes had been checked properly. To make the results better, new electrodes should have been used for each experiment.
I also think that the same equipment should have been used throughout.