Bouncy egg experiment
It’s fair to say the girls loved the bouncy egg experiment. You can see in our video below. There are few greater pleasures in life than discovering that the everyday can be magical.
Aside from the egg and the vinegar this experiment is completely free. Just ingredients you will find in your kitchen. We tend to do this when we have eggs that have gone past their ‘use by’ date and so would be unusable otherwise.
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- Take a raw uncooked egg and completely submerge it in vinegar
- Leave it for at least 24 hours. You can come back and check on it with the kids to see how it changes. The skin bubbles and turns an opaque white. Very fascinating to watch!
- Don’t leave it for more than 3 days. We made this mistake with this experiment before. The egg expanded so much and when we tried to bounce it we very quickly got a messy messy mess.
- You’ll know the egg is ready when it looks almost transparent.
- After the time is up take the egg out of the vinegar and drop it gently on the table top. Watch it bounce. It’s almost rubbery.
- As you can see from our video below there were moments of enthusiasm which resulted in some very illuminating realisations that the egg was indeed still raw and not boiled haha!
The Science behind the bouncy egg experiment?
Why does the egg become bouncy when left in vinegar?
Vinegar is an acid. The vinegar that you can consume typically contains between 4% and 7% acetic acid.
The shell of an egg is made of calcium carbonate.
When the egg and the vinegar came into contact, this started a chemical reaction that broke down the calcium carbonate and released carbon dioxide. That’s what we could see when we saw the bubbles on the surface of the egg.
So when we leave the egg for at least 24hrs it allows this process to continue until we can rub off the shell of the egg easily.
But won’t the egg under the shell break even more easily?
Under the shell of the egg we find the membrane.
The membrane is remarkably tough. It contains keratin, which you also find in human hair.
So even though the membrane is semi-permeable it is also pretty tough. Which is why it is so rubbery and it bounces.
Remember our super inflated egg?
We also had some failed experiments. Where eggs became really huge after we forgot them in vinegar for a week (*happens very easily trust me*)
This is due to osmosis. This is where molecules of a solvent pass through a semi-permeable membrane from a less concentrated solution to a more concentrated one.
The egg membrane is semi-permeable.
The egg has a high concentration of proteins and fats inside it.
The vinegar has a lower concentrated solution than the egg. As a result while the acid from the vinegar is breaking down the shell of the egg, water continues to pass through the semi-permeable membrane of the egg.
It does this until the concentration levels of the egg and the vinegar are pretty much equal.
One very round egg.
But as we discovered after a week, also one very weak membrane.
This experiment is a firm favourite with Ano and Vongai. So even though right now they don’t know the science behind it, it’s still a fun one to do together.
Each time mommy says a bit more about the science stuff, but to be honest this is just such a fantastic little magic trick that it will stick in their minds for a while anyway!
If you do this at home with your little ones do let us know how it went. Enjoy.
This post and other free STEM activities can be found on this page.