Electroplating a spoon
Hang a steel spoon in a solution of a metal salt and pass a current. Change the coating metal, the current and the time, and see how much metal is deposited and how thick the coat on the spoon grows.
Core concept
In electroplating the object is the cathode (−) and the coating metal the anode (+); the metal deposited is proportional to the charge passed, current × time
Topic: Chemical effects of electric current
Some liquids, such as a solution: A mixture where one substance has dissolved completely in a liquid, like salt water. All key words of copper sulphate, conduct electricity. When a current passes, the liquid changes chemically: this is a chemical effect of the current. In electroplating, the object to be coated, a spoon, is joined to the negative terminal (the cathode) and a piece of the coating metal to the positive terminal (the anode). Metal from the solution settles on the spoon, and the anode slowly dissolve: To mix into a liquid so completely that you can no longer see the pieces. All key words to replace it. The charge passed is Q = current × time, in coulombs, and the metal deposited is proportional to it: twice the current, or twice the time, gives twice the metal. Taps are chrome-plated, ornaments are silver- or gold-plated, and iron is coated with zinc (galvanised) so it does not rust.
What you will learn
- Explain that electroplating is a chemical effect of electric current.
- Identify the cathode and the anode in an electroplating cell.
- Relate the metal deposited to the current and the time.
- Give everyday uses of electroplating.
Before you start
- Know that some liquids conduct electricity.
Materials
- A steel spoon, a strip of copper, copper sulphate solution and connecting wires
Equipment
- A low-voltage battery or power supply and an ammeter
Procedure
- Record copper at 1 A for 30 minutes.
- Double the current to 2 A and record.
- Double the time to 60 minutes and record.
- Change the metal to silver and record.
How this simulation is simplified
- All the current goes into depositing metal, the coat spreads evenly over a spoon of 20 cm², and the solution holds the same metal as the anode.