- Age:5+
- Time:10 min + 24–48h soak
- Difficulty:Easy
- Mess level:Low
- Supervision:No
If you are looking for a fun and easy kitchen science experiment, the naked egg experiment is the right one for you. It has great teaching power, and your children will learn a lot about how cells in all living organisms work. All we need is some common kitchen supplies, and we will be able to look inside an egg, see what hides behind that thick shell, and play some fun games afterward.
Anatomy of an Egg
The main parts of an egg are the shell, membrane, albumen (egg white), and yolk.
The eggshell is made primarily out of calcium carbonate crystals (95–97%) which are held together by a protein matrix. That protein matrix gives the shell its strength; without it, the shell would crumble apart. The eggshell protects the egg from mechanical damage, but also from bacteria and dust.
Anatomy of an egg: shell, membranes, egg white and yolk.
An egg is more complex and sturdy than it seems at first glance.
The membrane is made out of proteins and it protects the inner part of the egg from bacterial infection. There are actually two membranes - an outer and an inner one - and they are surprisingly strong.
Albumen, or egg white, consists of around 40 different proteins in addition to water (90%). Its main purpose is to provide extra nutrition to the embryo, as well as protecting it.
The yolk is the main source of nutrition for the embryo. It consists of proteins, vitamins, minerals, fat, and some water.
The science behind the naked egg experiment
If we soak an egg in vinegar, we start an acid–base reaction. The acetic acid from the vinegar reacts with the calcium carbonate (a base) in the eggshell. The products of that reaction are calcium acetate, water, and carbon dioxide.
You can notice bubbles forming on the surface of the eggshell, that's the sign of the newly created carbon dioxide. After some time, the shell dissolves completely and all that holds the egg together are its membranes.
💡 Did you know?
This is the same kind of reaction that damages your teeth. Tooth enamel is rich in calcium, so acidic, sugary drinks slowly dissolve it just like vinegar dissolves an eggshell. Watching it happen to an egg is a memorable reminder to brush after sweets!
Once the hard, outer shell is dissolved, the egg becomes translucent (hence the name "naked egg"). When we hold the egg up to a light source, it looks like it's glowing and we can see the yolk inside. All that is keeping the egg together is a thin semipermeable membrane.
This leads to the next side effect of putting the egg in vinegar. You will notice that the egg becomes a little bigger. That is because some of the water in the vinegar solution (even the strongest household vinegar is more than 90% water) travels through the egg's semipermeable membrane to equalize the concentration of water inside and outside the egg. The process of water traveling through a semipermeable membrane is called osmosis, and it is characteristic of all living beings.
On the other hand, if we put our naked egg into corn syrup, the egg will shrink. That is because corn syrup has a lower concentration of water, so water moves out of the egg to equalize the water concentration on both sides.
You leave a naked egg overnight in a glass of corn syrup. What happens to it?
Make your prediction, then tap an answer to check!
If you'd like to watch how we did it, check the video for making the bouncy egg at the start of the article. Or if you prefer reading, continue with the step-by-step instructions below.
Materials needed for the naked egg experiment
The whole experiment takes just an egg, vinegar and a glass.
All we need for the naked egg experiment is some vinegar, a glass, and an egg.
- Egg
- Vinegar
- Glass
- Source of light (flashlight, mobile phone)
Instructions for a bouncy, glowing egg
Bubbles of carbon dioxide form as the vinegar dissolves the eggshell.
You will see bubbles forming when the vinegar starts to react with the eggshell.
- Carefully place an egg into a glass.
- Pour vinegar over it until the egg is completely covered. Instead of vinegar, you can use cola, rubbing alcohol, or orange juice, since they are acidic enough to produce the same effect. Leave it for at least 24 hours, depending on the strength of the vinegar (9% vinegar takes about 24 hours). If the egg is fresh it will probably float up, so gently rotate it now and then with a spoon so the shell dissolves evenly on all sides.
- After 24–48 hours, remove the egg from the solution and rinse it gently under running water.
Congratulations! You now have a rubbery, transparent egg, also commonly called a naked egg. Experiment with it! How high can it bounce? Can it survive a drop from 10 cm? Work your way up little by little - and do your bounce tests over a tray, a sink, or outside.
⚠️ Not for eating
The naked egg is still raw and has been sitting out for a day or two, so it is for playing and observing - not for eating. Use a fresh egg, and wash your hands after handling it and any spills.
Place the naked egg on a light source and it glows.
Holding the egg up to a light source makes it glow, and you can see the yolk inside.
If you hold your naked egg up to a light source, you'll see a cool glowing egg! You can also investigate the anatomy of the egg, since you can see its parts very clearly through the transparent membrane.
What will you develop and learn
- Anatomy of an egg
- Chemical reactions
- Osmosis and semipermeable membranes
- The scientific method
Don't forget to experiment! Discover new things you can do with your egg and keep notes on all your findings - that's the best way to learn. We'd love to hear all about your experiments, so share them in a comment.
Key takeaways
- Vinegar's acetic acid reacts with the calcium carbonate in the shell, dissolving it and releasing carbon dioxide bubbles.
- Once the shell is gone, only the thin semipermeable membrane holds the egg together - that's the "naked egg."
- Hold it up to a light and it glows, letting you see the yolk inside.
- Water moves into the egg by osmosis, so it swells; put it in corn syrup and it shrinks.
- The naked egg is raw - it's for playing and observing, not eating.
Frequently Asked Questions
What happens to an egg in vinegar?
The vinegar's acetic acid reacts with the calcium carbonate in the shell. Bubbles of carbon dioxide form, and over about 24–48 hours the hard shell dissolves completely, leaving a translucent, rubbery "naked egg" held together only by its membrane.
How long does it take to make a naked egg?
Usually 24 to 48 hours. Standard 9% household vinegar dissolves the shell in about a day; weaker vinegar takes longer. If any shell remains after 24 hours, gently rinse the egg and give it fresh vinegar for another day.
Why does the naked egg bounce?
With the rigid shell gone, the egg is held together by its flexible, rubbery membrane. That membrane can stretch and absorb the impact of a small drop, so the egg bounces instead of shattering. Start with tiny drops - it will still break if you drop it from too high.
Why does the naked egg glow?
Without the opaque shell, the egg becomes translucent. When you hold it up to a flashlight or phone light, the light passes through the membrane and egg white and lights it up from the inside, so it appears to glow - and you can see the yolk.
Why does the egg get bigger in vinegar?
Household vinegar is more than 90% water, and the inside of the egg has a lower water concentration. Through osmosis, water moves across the semipermeable membrane into the egg to balance the two sides, so the egg swells and gets bigger.
Can you eat the naked egg?
No. It is still a raw egg that has been sitting out at room temperature for a day or two in vinegar, so it is not safe to eat. Keep it for playing and observing, and use a separate fresh egg if you want to cook.
Can I use something other than vinegar?
Yes. Any mild acid works - cola, orange juice, or rubbing alcohol will also dissolve the shell, though they may take longer or leave a color. Vinegar is cheapest and fastest, which is why it's the classic choice.
And if you're interested in more similar STEM activities, check out the simple but great orange density experiment. Be sure to see how to demonstrate osmosis with gummy bears and how to learn about pressure with the can crush experiment.
