Science Magic: How to Make Floating Eggs!
There are two ways to create floating eggs. One method is to use rotten eggs. However, if you've ever smelt a rotten egg you'll know why we don't recomment this method. Rotten eggs truly smell rotten. They absolutely stink!!!
The other more 'magic' method for making floating eggs is to use fresh eggs and salt. Yes, that's right ... salt!
Here's what you need to do ...
Floating Eggs: Step 1
Fill a glass with fresh water and then place a fresh, uncooked egg in it. Watch what happens.
The egg will sink. If it doesn't, don't break the egg!!! There's a good chance it's rotten! (We'll tell you more about that in a minute).
Floating Eggs: Step 2
After confirming that your egg sinks in fresh water, remove the egg and stir in 3 heaped teaspoons of salt. Carefuly place the egg back into the salty water while muttering a few magic words (e.g., abracadabra - this is, after all, a magic trick, right?). Watch what happens!
Instead of sinking, the egg will now float to the top of the glass just like magic ... even if you didn't dramatise the experiment with a few magic words! :o
Congratulations, you've done it! You've made an egg float!
Try Another Floating Egg Challenge
Repeat the experiment, starting with a new glass of fresh water. See if you can add just enough salt to make the egg float half-way up the glass - i.e., neither sinking nor floating ... just suspended in the middle of the glassful of water. Do you think it's possible? Can YOU do it?
Why Do The Floating Eggs Float?
The answer lies in the word 'density'. The egg sinks in fresh water because the water is less dense than the egg. The egg contains more matter than the same amount of water.
However, as you add salt to the water, the density of the water increases so that in the end, the density of the water becomes greater than the density of the egg. The density of the water, being greater than the density of the egg, causes the egg to float.
Why Do Rotten Eggs Float?
Before we finish, do you want to know why rotten eggs float and fresh eggs don't?
As an egg ages, air seeps through the eggshell and into the egg. The air cell that is naturally formed inside an egg becomes larger which makes the rotten egg buoyant.
This is handy information because the next time you want to check whether the egg you are about to cook is fresh or not, you'll know that all you have to do is to put the egg in a bowl of water. If the egg sinks, it's fresh. If the large end of the egg tilts upwards, the egg is a bit older than a fresh egg. If it floats, don't even think about cooking the egg unless, of course, you like eating rotten eggs! :o
By the way, if you're looking for a humourous story full of eggs, then check out Farmer Blake and Sneaky Snake.
Return to the Articles List for other children's learning activities or children's book reviews.