Grade Level: 7th - 9th; Type: Chemistry
This science project will explore the components of a battery, specifically how the conductivity of the solution in the battery affects how much electricity it generates.
- How can you make electricity from simple objects around the house?
- How does the amount of salt in a solution affect the solution’s ability to conduct energy?
We use batteries in everything – from IPods to cars. But how does a battery work? In this science project, you will build a battery and see how one of its components contributes to its ability to generate electricity.
- Small glass jar
- Measuring spoons
- Zinc-coated nail
- Copper-coated wire
- 2 insulated wires with alligator clips on both ends.
- Voltmeter (borrowed)
- Graph paper, optional
- Make a saltwater solution by mixing a small jar of water with a teaspoon of salt.
- Place a zinc-coated nail into the solution, and tape it to one side of the cup securely. This will be the negative electrode.
- Place a copper-coated wire into the solution, and tape it to the other side of the cup securely. This will be the positive electrode.
- Open the alligator clip on one wire by squeezing it, and attach it to the end of the zinc-coated wire sticking out of the solution.
- Open the alligator clip on the other end of the wire, and attach it to the negative pole of the voltmeter.
- Repeat Steps 4 and 5 to connect the copper-coated nail to the positive pole of the voltmeter.
- Look at the dial on the voltmeter. How much current does it show flowing between the two electrodes?
- Add another teaspoon of salt to the water. How much current does the voltmeter show now? Continue adding teaspoons of salt and recording the reading on the voltmeter in a chart, such as the one below.
If you’d like, you can make a line graph showing the relationship between the amount of salt in the water and the current that flows between the two electrodes. Is there a point at which the current stops increasing?
Terms/Concepts:Voltage; How does a voltmeter work?; What are the parts of a battery (e.g., electrodes)?
- Easy Genius Science Projects with Chemistry, by Robert Gardener. Pp 55-57.