The materials required for the science fair project:
- 3 beakers
- 3 salt bridge
- 300ml zinc sulfide
- 300ml copper sulfide
- 300ml lead sulfide
- Zinc plate 25mm x 100mm
- Copper plate 25mm x 100mm
- Lead plate 25mm x 100mm
- 2 jumper wire with crocodile clip at both ends
- A digital voltmeter
- A marker pen
1. For this science fair project, the independent variable is the type of metal electrodes and electrolyte solutions used. The dependent variable is the voltage produced by the Galvanic cell. This is measured using the digital voltmeter. The constants (control variables) are the amount of electrolyte solution, the size of the electrodes, the room temperature and the size of the salt bridge.
2. The zinc, copper and lead plates are first cleaned.
3. The 3 beakers are each filled with 300ml of zinc sulfide, copper sulfide and lead sulfide. The beakers are also labeled accordingly on the outside using the marker pen.
4. The metal electrodes are placed in the beakers according to the electrolyte solutions. For example the copper plate is placed in the beaker containing the copper sulfide.
5. The experiment is started using the beakers containing lead and copper. The two beakers are placed side by side and the salt bridge is placed in the beakers as shown in figure 1 above. The digital voltmeter is connected across the 2 electrodes and the voltage measurement is taken. The measured voltage is recorded in the table given below.
6. The procedure 5 is again repeated using the copper - zinc combination and zinc – lead combinations. The measured voltages are all recorded in the table given below.
Always handle chemicals with care. Safety gear (goggles, lab coats and gloves) should be worn when handling chemicals.