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Science Rocks!

Saltwater Tester


your results

Sent in by:
The ZOOMers

Measuring salt never sounded so good.

Materials Needed

  • masking tape
  • 9-volt battery
  • buzzer
  • 2 Popsicle™ sticks
  • aluminum foil
  • water
  • saltwater



  1. Check with a grown-up before you begin.
  2. How can you tell if water is salty? You could taste it - or you could use a saltwater tester!
  3. A saltwater tester uses electricity to tell you if water is salty or not. Here's how to make your own.
  4. First, cover two Popsicle™ sticks with metal - the ZOOMers used aluminum foil.
  5. Then, get a buzzer - you can buy one at an electronics store - and tape the red wire of the buzzer to the positive end of the battery. The positive end will have a plus sign on it.
  6. Next, tape one foil-covered Popsicle™ stick to the black wire of the buzzer. Tape the other one to the negative end of the battery. The negative end will have a minus sign on it.
  7. You can see if your tester is working by touching the metal together. This will complete the circuit and make the buzzer buzz. If it doesn't buzz, check your connections to make sure everything is taped together in the right way.
  8. Now to use your saltwater tester, put just the tips of the metal in saltwater, about an inch apart. Make sure the two metal parts don't touch. The saltwater will act like a wire, connecting the metal sticks, completing the circuit, and making the buzzer buzz.

Here's the sci scoop on how this works. The buzzer buzzes in saltwater because the saltwater acts like an invisible wire to connect the circuit. That's because when you add salt to water, the salt molecules dissolve in the water and break into smaller parts called ions. The ions carry electricity through the water.
Fresh water doesn't have these ions. So it's harder for the electricity to move through the water. It doesn't complete the circuit, and the buzzer doesn't buzz.
What else besides saltwater will conduct electricity and make your buzzer buzz? Try sugar water, vinegar, or whatever else you can think of. Check it out, and be sure to send your results to ZOOM!

Some of your Results

Zuha, age 13 of Markham, ON wrote:
its was reallly koool! everyone got amazed im going to do it for my next years project as well!!! it is pretty good for a grade 8s projects!!

Tarun, age 11 of Chennai, Tamil Nadu, India wrote:
It was cool... my buzzer had really long wires, so it was easy

Marissa, age 13 of San Antonio wrote:
i tested is with vinigar and milk and the buzzer went crazy I am glad I did it for my science fair project

Makyla, age 7 of Newport News, VA wrote:
It buzz alot! I LOVE IT!

Nicole & Audrey of Moraga, CA wrote:
We are doing it for the school science project, alot of things have salt in it like chocolate milk.

Emma, age 14 of Harper, TX wrote:
Well I had a bit longer put together time than others would have because my buzzer had the wires cut off of them real short, that was no problem for me though. I just grabbed my soldering iron and solder and then soldered it together. When I got it together the first time I tried it the voltage of the battery was to high for my buzzer so it buzzed in everything I tried. Even in air when it got to close together. So then I tried a regular double A battery and it buzzed in the Salt Water and not the Fresh Water, like it was supposed to do. It was fun! Thanks for showing how to do this easy experiment on the show and the website!

Zuha, age 12 of Markham, ON wrote:
it was soooo amazing when I tried it. I used different liquids like saltwater freshwater and sugar water. my question was which type of water will complete the circuit (or make the buzzzer buzz) by the way it took me forever to find a buzzer but I went to home depot and got it!!!

Ms. L's Class of Rock Island, IL wrote:
We had 6 stations, each with a different liquid to be tested. We tested salt water, Cherry Coke, chocolate milk, vinegar, sugar water and bottled water. We predicted which have salt. The only one we guessed wrong was chocolate milk. Who would have known that chocolate milk has LOTS of salt in it! Yuck! This was a fun experiment.

Mr. W's Class of Rock Island, IL wrote:
Our class rocks when we do science! We thought it was fun building the testers. Some of us had to try to get the connections more than once. But we all did it and then we tested different liquids. We predicted chocolate milk would NOT have salt in it, but boy, does it have LOTS of salt in it. The buzzers went crazy! Vinegar and cherry coke and of course salt water have lots of salt too. This experiment rocks!!

Dalia, age 13 wrote:
Some of the required materials were available but the others I tried different materials instead of them. It was a nice experiment. When I did it I observed that the more salt I add the sound of the buzzer become loudly. Also, when I put the sticks closer it also rang loudly. In addition, I found that all of the salt particles were attracted toward the aluminum foil. So the conclusion is that from the properties of ionic compounds is the electrical conductivity.

Abdul, age 13 of Jeddah, Saudi Arabia wrote:
after I followed the instructions it really buzzed. after that I didn't believe my eyes or ears finally it was a good topic to do.

Nouran, age 13 wrote:
Only water with salt worked. Water didn't work alone.

Mariam, age 13 of Jeddah, Saudi Arabia wrote:
The buuzzer buzzed in saltwater, but it didn't in th pure water. That means it is an electric conductor when dissolved in water or melted and that is because it is an ionic compound.

Raneem, age 13 wrote:
It worked in salty water because the salt dissolved into ions, and ions can carry electricity. While in water nothing happened with it.

Shurug, age 14 of Jeddah, Saudi Arabia wrote:
First, I covered the straws (I used straw instead of a popsicle sticks) using the aluminum foil. Instead of buzzer, I used light bulb, and I have to provide wires to connect the bulb into the battery, the first wire for the positive end of the battery and to the bulb. Then the other wire for the bulb and to the negative end of the battery. After that, I put the tips of the aluminum foil into the saltwater, and the bulb lit. So that's it. It's very easy, and interesting. I tried it on the water without salt but the bulb did not lit.

Mrs. H's Class, age 9 of IL wrote:
Our class did this experiment in science lab. We tested vinegar, chocolate milk, sugar water, salt water, cherry Pepsi and bottled spring water. We used 6 different testers, 4 buzzers and 2 motors. Results: vinegar-yes, chocolate milk-yes, sugar water-no, salt water-yes, cherry Pepsi-yes, bottled water-no. This was awesome. Some of us got different results, that's why we tried different motors and buzzers. The salt water was our control. Science rocks!

Ms. L's Class, age 12 of IL wrote:
Our class divided into 6 teams and each team built a saltwater tester. We had 2 different kinds of buzzers and 2 motors. We got mostly the same results in each team except for vinegar and bottled water. We think the bottled water got contaminated by the cherry Pepsi. But vinegar, chocolate milk, salt water and cherry Pepsi were definite yes for salt and the others were no. Our hypothesis was that chocolate milk does not have salt, but we were wrong! We love science!!

Mrs. L's Class, age 9 of IL wrote:
We tested 6 different liquids for salt. We liked building the saltwater tester. We used the scientific method to do this experiment. We found that vinegar, chocolate milk, salt water and cherry Pepsi all have salt in them. Sugar water and bottled water do not. Our teams work great together in science lab. Go science!!

Mrs. M's Class, age 9 of IL wrote:
We worked with our team in science lab to build the saltwater tester. We used the scientific method and predicted that chocolate milk and bottled water most likely would not have salt in them. Our hypothesis about the chocolate milk was wrong. It has lots of salt in it! Cherry Pepsi and saltwater and vinegar do too! We love science! It's fun to do experiments and discover new things.

Mrs. A's Class, age 12 of IL wrote:
We thought it was cool to build the saltwater tester then use it in different liquids. Our hypothesis was wrong about bottled water. We thought it contained salt but it doesn't! Three teams thought chocolate milk didn't have salt in it and 3 teams thought it did. So half of the teams' predictions were correct. It's fun to learn science with experiments!

Mrs. J's Class, age 9 of IL wrote:
We love science! We love experiments! This experiment was fun to do in science lab. We built 6 different testers then tested 6 different liquids. Our hypothesis was that vinegar and chocolate milk wouldn't have salt but that was wrong. They have LOTS of salt! We predicted correctly about the other liquids, so our hypotheses were right on those. Science rocks!!

Mr. N's Class, age 12 of IL wrote:
We did this experiment in science lab and liked building the testers. Our hypotheses were almost all correct about all the different liquids we tested. Chocolate milk, vinegar and cherry Pepsi all have salt in them. Of course, so does salt water. That was our control liquid. Some of us are going to build the tester at home and try other liquids like orange juice and white milk. Science is fun!!

Yu, age 8 of New York, NY wrote:
The saltwater tester buzzed when I put it in the salt water, it also buzzed when I put it in vinegar, it didn't buzz in fresh water or cold sugar water. It also buzzed in sugar water.

Madelyn, age 4 of Chicago, IL wrote:
Plain water no. Salt water yes. Sugar water no. Oxy Clean water yes.

Jaeden, age 10 of Brush Prairie, WA wrote:
i tried it but I added something to it. I put sugar in the water and baking soda and it was awesome.

Motasem, age 12 of Paterson, NJ wrote:
i used a light bulb instead of a buzzer and it worked.

Carolina, age 12 of Mount Vernon, NY wrote:
it was so easy. i've done it so many times yet it is interesting.

Ekene, age 10 of Baltimore, MD wrote:
I didnt feel any buzz I checked it twice but anyway it was really cool thanks for saving my butt!!!

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