Jul 07 , 2014
Understanding Water Conductivity for Kids
When we think of electricity, we usually imagine wires in our houses or the huge electrical cable lines outdoors. But did you know that water can also be used to conduct electricity? In fact, its a very powerful conductor! The temperature of the water plays a large role in how well it conducts electricity. Hot water conducts better in general. One reason that we might want to estimate the conductivity of some water is to find the amount of solids that are dissolved in it, such as salt. When you stir salt into warm water, it dissolves. A chemical reaction takes place, so the solid salt grains turn into positive and negative ions. These ions help to carry electricity in the water. Keep in mind that adding salt to water will only work until a point, and after that adding more salt will not have much effect any more.
A Salt Water Electricity Experiment
Scientists use very special tools when they work with water and electricity. However, you can make your very own kit at home with just a few simple items and directions below. Be very careful when you experiment with electricity and ask a parent or teacher to supervise you. Through this activity, you will see first-hand how water can conduct electricity.
Materials
Collect all of the following items before starting your experiment.
- Packing or masking tape
- One 9 volt battery
- An electronic buzzer (you can find this at the local electronics store)
- Two wood popsicle sticks
- Aluminum foil
- Salt
- A large bowl of cold clean water
- A large bowl of warm clean water
Method
- To get started, wrap the aluminum foil snuggly around the two wooden sticks so they are fully covered.
- Next, get the buzzer and identify the red and black wires on it.
- Use some tape to attach the red wire to the positive part of the battery (where it shows a + sign), and the black wire to the negative part (- sign).
- Add a few spoons of salt to the bowl of warm water and stir until all the salt dissolves.
- Now its time to test whether the buzzer works. Make the two wooden sticks touch each other. If the buzzer makes a noise, that means it works. If there is no noise, check that the wires are taped tightly and that the foil covers the entire sticks.
- This is the exciting part! Place only the ends of the sticks into your bowl of salt water. They should not be touching each other. Does the buzzer make a sound?
- Remove the sticks from the water and wipe them dry. Now place them in the bowl of clean water. Is there any sound this time?
Results
If you performed the experiment correctly, you will have found that the buzzer makes a noise with the salt water, but not with the clean water. Why is this? The salt in the water dissolved and broke down into ions. An ion is an extremely small particle; in fact, its an atom that has a positive or negative charge. This means that it helps the water to behave as though it were a wire that connected the buzzers red and black wires.
As you can see now, it was the salt that made the difference in the water. The bowl of clean water did not have any salt or ions, so it was unable to conduct electricity. The link that you created with the battery, buzzer, sticks and water is called a circuit. Since water is such a good conductor, we must be extremely careful whenever there are any plugged electronics near a source of water. Since our bodies contain a lot of water, it means that humans are actually good conductors of electricity too! However, it is very dangerous if we conduct electricity and it could hurt us very badly or even kill us. For this reason, you should never touch any machines, wires or plug points with wet hands.
Now that you know all about water and conducting electricity, can you think of any ways in which we could use it in the real world? Do you think it could be used to help save resources or reduce pollution?
Additional Resources
Check out these fascinating resources below to learn more about how water conducts electricity!
