How to Test Salt Water for Electrical Conductivity

My son just completed his 5th Grade Science Fair Project. He decided to test saltwater and other various liquids to see if they will conduct electricity.

His teacher told me his project was a huge hit with all the boys. Nothing they love better than creating a loud noise while playing with electricity.

Difficulty: Moderate

Instructions

Things You'll Need:

• a buzzer (purchased for about $5 at Radio Shack)
• two popsicle or craft sticks
• tin foil
• a V9 battery
• masking tape
• cups
• salt water (we used two tablespoons salt in our water)
• any other liquids you would like to test

1. Take your craft sticks (or popsicle sticks) and cover them with tin foil.

2. Take the red wire of your buzzer and attach it with masking tape to the positive end of your battery (you'll see a plus sign)

3. Take the black wire of the buzzer and attach it with masking tape to one of the foil-covered craft sticks. Really tape it down. If the wire pulls away from the stick, the experiment will not work.

4. Take the remaining craft stick and tape it to the negative electrode on the battery. Again, really use that masking tape to be certain the tin foil stays in contact with the negative end of the battery.

5. Test your Tester
   
   Gently touch the two craft sticks together. If you've made your tester properly, you'll hear a buzz. Be prepared, the first buzz may make you jump a little.

6. Test your Salt Water
   
   Dip the two ends of your tester into the salt water. Leave a small gap between the sticks of one to two inches. If the buzzer buzzes, you are conducting electricity.

7. Test other Liquids
   
   Once you've tested salt water, you may find yourself wanting to test every other liquid in the house. We tested tap water, salt water, V-8, soda and even ice cubes.

Tips & Warnings

• Remember the salt in the water dissolves into ions which, in turn, conduct electricity. The more salt in your water, the louder your buzzer will buzz.
• Although the ice cube did not buzz, it did click faintly and the sodium-free water did give off a very faint buzz.
• Soda and many drinks contain sodium and will therefore buzz.
• Although nobody got shocked with the tester, you still want to handle your creation with care. My son wrapped the top ends of the foil-covered sticks with masking tape because he said the foil would get hot.

[starlet67]

on 6/11/2009 Now I know how to do this!

[edieness]

on 6/11/2009 Well written article on How to Test Salt Water for Electrical Conductivity.5*

[Mitestarossa]

on 6/11/2009 Thank you for letting me know, I did not know this was possible.

[GreenMomma]

on 6/10/2009 What a cool idea!

[Jolocol]

on 6/9/2009 How fun! I'm putting this one in favorites for the next school year. Sounds like your son had a great experience. Too cool!