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Science Projects > Physics & Engineering Projects > Saltwater Density Science Project
Saltwater Density Science Project
If you have the advantage of visiting the ocean or the Great Salt Lake in Utah this summer, you may find your swimming experience in these bodies of water to be slightly different than swimming in a freshwater lake or river. If you accidentally get water in your mouth or eyes from the ocean or the Great Salt Lake, you will certainly notice the saltiness of the water. But what about floating? Is it easier to float in the ocean or Great Salt Lake than in freshwater? And if there is a difference in your ability to float, do you think that water from one body of water is denser than water from another body of water? Which do you think is the most dense? Freshwater from a lake, saltwater from the ocean, or saltwater from the Great Salt Lake? Do this saltwater density experiment to find out!
What You Need:
- 3 test tubes (or use 3 jars instead)
- Jar, drinking glass, or beaker (for making the salt solutions)
- Salt (you can use just regular table salt)
- Medicine dropper
- Red, blue, and yellow food coloring
- Graduated cylinder
- Measuring cup or beaker that measures in 10’s of ml
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What You Do:
2. Fill the dropper with water from the “Great Salt Lake” test tube, and add it to the graduated cylinder. You may need to add two or three droppers full of water to the cylinder.
3. Rinse the dropper out really well with faucet water to avoid cross contamination of salt and food coloring.
4. Fill the dropper with water from the “ocean” test tube. This time, very gently and carefully add it to the graduated cylinder so that the force of the water being squeezed out of the dropper doesn’t mix the two waters. Add about the same amount of “ocean water” to the graduated cylinder as there is “Great Salt Lake water.” Rinse out the dropper with faucet water.
5. Fill the dropper with water from the “freshwater” test tube. Again, add the water very gently to the water already in the graduated cylinder to avoid mixing the water, and add about the same amount of freshwater as “ocean water.”
What Happened:
Density is the measure of how much matter (mass) is packed into an item or material compared to the amount of space (volume) it takes up. A material that is more dense (e.g. lead) will weigh more than a material that is less dense (e.g. cork) even though they both take up the same amount of space. Or, to think of density another way, 10 pounds of cork takes up a lot more space than 10 pounds of lead.
To really prove that the “Great Salt Lake water” is the most dense, the freshwater is the least dense, and the “ocean water” has a density somewhere in between these two types of water, try this experiment again except this time reverse the order that the solutions were placed in the graduated cylinder. Do they sit on top of each other as they did before or do they mix up?
More Water Projects:
- Surface Tension
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Exploring the Density of Liquids with Salt
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This modified version of a lava lamp is definitely one of our favorite cool science experiments ! It’s a super fun way for kids to explore the density of liquids using materials you have right in your kitchen.
Follow our Science for Kids Pinterest board!
We have a lot of cool science experiments for kids on Buggy and Buddy like this Baggie Burst experiment and exploring Colorful Chemical Reactions ! I think this exploration of liquid density ranks right up there with our favorites!
With just a few household materials, children can explore the density of liquids and even practice mixing colors in a super fun way! (This post contains affiliate links.)
See it in action here!
Cool Science Experiments: Density of Liquids
Materials for science experiment.
- Clear glass
- Vegetable oil
- Food coloring
Science Experiment Procedure
1. Fill your clear glass about 2/3 of the way with water.
2. Pour vegetable oil into your cup. (You want to create a layer that’s about 3/4-1 inch high.) What happens to the oil after you pour it in your cup? Why do you think this happens?
3. Add one drop of food coloring to the cup. What happens to the drop of food coloring? Why do you think this happens?
4. Sprinkle salt into your cup and watch what happens!
5. Continue adding more salt and observe. (The kids started by doing small sprinkles of salt, then progressed to adding big pinches of salt, and then spoonfuls of salt.)
6. Allow time for your child to explore the setup on their own. Lucy (6 years old) wanted to add different colors of food coloring to her cup to see what would happen.
This science activity was a great sensory experiment for Theo, my 3 year old. He loved watching all the movement in the cup and would even stick his finger in the liquids to see what would happen!
What’s Going On?
In the beginning of the experiment, the oil settles above the water because it is less dense. When you add salt to the to the cup, the salt sinks to the bottom of the cup since it is heavier than the other two liquids. The salt carries a blob of oil with it. As the salt begins to dissolve in the water, it releases the oil which floats back up to the top.
Be sure to try this similar density experiment – comes with a free printable too!
Want to go even further?
Even more activities to inspire creativity and critical thinking for various ages.
1. Try this Dancing Raisins experiment. How is it similar to the one you just did? How is it different?
2. Explore the density of objects in this simple sink and float experiment .
3. Try this Seven Layer Density Column experiment.
Chelsey was previously an elementary teacher for 12 years and is now creating, playing, and learning at home with her two children. You can follow Buggy and Buddy on Twitter or Facebook by clicking on the icons below.
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Salt Water Density Experiment: Here's a brightly colored science experiment that not only looks cool, but allows students to develop their own understanding of density! I used this experiment for a freshman Physical Science class, but it could be adapted for many age….
Try Salt Water Density Experiment examines the question, "How does food coloring react to salt & fresh water? Free Observation Sheets!
1. Add one drop of blue food coloring to the test tube of freshwater, one drop of yellow food coloring to the test tube of “ocean water”, and one drop of red food coloring to the test tube of “Great Salt Lake water.”.
The Salt Water Density Straw is the epitome of kitchen science. You'll use materials are right in your house, and with just a bit of salt, you'll create a colorful experience that will have young …
Lucy (6 years old) wanted to add different colors of food coloring to her cup to see what would happen. This science activity was a great sensory experiment for Theo, my 3 year old. He loved watching all the movement in …
1. Fill both of your cups with tap water. 2. Add 2 tablespoons of salt to one of your cups. Stir the water with the spoon until the salt is all dissolved, then add a couple drops of food colouring …