1 Hardboiled Egg
Clear, Wide-Mouth Glass or Jar
1. Place your egg gently in your glass or jar.
2. Cover with vinegar. At this point, you will see bubbles begin to form on the outside of the egg as air escapes through the eggshell’s pores.
Bubbles Forming as Air Escapes
3. Let your egg sit for about 24 hours.
4. Remove the egg from the jar and hold it under slow running water as you gently run your finger over the surface of the egg.
Gently Rub Off Shell
5. Continue rubbing your fingers over the egg to gently remove as much of the shell as you can. It will appear as a white, chalky residue on your fingers.
6. Dump out the old vinegar and replace it with new vinegar. Let the egg sit for another 24 hours and try to gently wipe off the shell under water again.
7. Repeat step 6 as needed until you remove the entire eggshell.
An eggshell contains calcium carbonate. As an acid, vinegar dissolves the shell, forming carbon dioxide, which can be observed by the “foam” you may have seen after the first 24 hours. You’ll notice that after gently removing the shell, the egg membrane is still intact. You can see it best by finding the little pocket of air created at the tip of your hardboiled egg.
This experiment will also work with a raw egg, so give it a try if you’re brave! Just make sure you don’t put too much pressure on the egg. Be sure to hold it over the sink as you remove the shell… just in case!
Fit an Egg in a Jar
1 peeled hardboiled egg
Jar with a mouth large enough to allow your egg to sit on top (we used an old milk jar)
Warning: This experiment requires an adult helper.
1. Moisten the mouth of the jar.
2. Have an adult strike a match and light a piece of paper on fire.
3. Place the lit paper in your jar.
4. Place the egg on the jar’s mouth.
5. Watch as the fire is extinguished.
6. Watch as the egg gets sucked into the jar!
Watch this experiment in action!
The fire in the jar heats the air, making it expand. When the egg is placed on top of the jar, it prevents oxygen from entering the jar. Since fire needs oxygen to burn, the fire is extinguished. As the fire goes out, the air molecules begin to cool, moving closer together. This creates a vacuum inside the jar and the egg is sucked inside!
2 Clear Jars or Glasses
About 5tbsp. Salt (preferably Kosher salt, but table salt will work)
1. Fill one glass with about 2 cups of tap water.
2. Fill the other glass with about 2 cups of warm water and stir in salt until dissolved.
3. Gently place an egg in each glass.
4. Observe the difference!
Floating Egg Experiment Results
The answer is all in density. An egg is denser than fresh water and sinks. But salt water is denser than fresh water – when salt is added and dissolves, it breaks down into ions that are then attracted to the water molecules. This attraction causes them to bind tightly and now there are more particles in the water compared to fresh. The egg is now pushing on a denser liquid and does not sink.
Think about this the next time you are at the beach – it is much easier to float in the open salt water of the ocean than a lake or swimming pool!