Can you make an egg float?
Keep the egg the same and change the water. Find out whether salt can help it rise. For a fair comparison, move one egg between two cups.
What should happen
The egg rests at the bottom in plain water and rises in sufficiently salty water. An egg that already floats in plain water is unsuitable for this comparison.
Let’s do it step by step
4 stepsStart with equal amounts
Pour the same amount of water into each cup. Leave enough space so adding the egg will not cause a spill.
Test plain water
Lower the egg carefully into the first cup with a spoon. Let it settle and note its position.
Change only the water
Add three tablespoons of salt to the second cup. Stir well until dissolved. Keep the egg in the first cup for now.
Compare with salty water
Move the same egg to the second cup. If it still sinks, remove it, dissolve another spoonful and try again. Record the amount.
Now we know why
Ages 5–6, with an adult
Salt dissolves in the water. This water supports the egg more strongly from below. The egg did not become lighter; we changed the water around it.
Ages 7–10
Density tells us how much mass a certain volume contains. Salt water is denser than plain water. When the solution becomes dense enough, the egg can float.
Ages 11–14
Buoyant force equals the weight of displaced liquid. At the same submerged volume, denser liquid provides a greater force. The egg rises until the displaced liquid’s weight balances its own. The salt required varies with the egg and water volume.
Salt does not reduce the egg’s mass or form a cushion beneath it. It raises the solution’s density.
If it turns out differently
The egg sinks in both cups
Remove it, dissolve another spoonful of salt in the second cup and retry.
The egg floats immediately
Use another egg that sinks in plain water for the comparison.
Lots of salt remains on the bottom
Wait and stir. Do not keep adding salt to a saturated solution; restart with measured fresh water.
A question for the explorer
Why do we move the same egg instead of comparing two different eggs?
What if…
Record the salt amount when the egg rises. Then add small amounts of plain water to the salty cup and observe the reverse change. Do not overfill it.
After the experiment
An adult removes the egg. Empty the solutions, wash dishes and surfaces, and wash your hands.
Continue on screen
Change conditions in the interactive model and explore the science.
Open the model ↗Sources and images
Text and illustrations prepared for Veda. AI-created illustrations show the intended setup; real results may vary.