Bouncy Rainbow Eggs

Rachel / February 13, 2019

A while ago we decided to do the naked egg experiment! After browsing through some ideas, I came across this awesome resource.

Included in the resource are labels for jars
6 versions of experiment journals
Observation drawing page
Experiment writing pages

For this experiment you will need…

This experiment is super simple, but really effective. We had a lot of fun with it. I found that when we added colour the eggs looked fantastic. We did use a highlighter for one of them to see if we could get a glow in the dark egg, but unfortunately the egg was dropped and it splattered everywhere – so no result pictures for that one. 🙁

Depending on how many eggs you want to do, pop one in each jar, carefully, and then cover with vinegar. (Add a few drops of liquid watercolour should you wish to make them colourful and vibrant)
The one on the left was our highlighter egg that didn’t work, 🙁 (must try that one again at some point)
Love to see my little scientists at work!
On day two the egg started to get bubbles all over it –
These are bubbles of carbon dioxide gas from the reaction.
By day three we had a layer of scum at the top of the jar – this is the shell starting to dissolve.
On day four there was more scum on the surface – our eggs were coming on nicely
By day five our shells had completely dissolved and were ready to CAREFULLY rinse off. (At this point, the eggs are so delicate that they are easy to break)
These were our results! You will notice that the eggs are a bit bigger than when you first started. This is because some of the vinegar has moved through the membranes to the inside of the egg. The membranes are semi-permeable and allow liquid to move through them. This is called OSMOSIS. It is also the reason that the colour has transferred, our eggs were way more vibrant than we expected.
We took our eggs down into the cellar so that we could light them up with a torch – this was really effective and because the shell had dissolved, we could see the yolk moving around in the egg white.

We decided that we wanted to see how bouncy these eggs could be so we took them back outside and had some fun with them.
This is the semi-permeable membrane that was holding it altogether! 🙂

I’m going to let Steve Spangler explain how this all works – he is one of my favourites…

Starting with the bubbles you saw forming on the shell – these are carbon dioxide (CO2). Vinegar is an acid called acetic acid (CH3COOH), and white vinegar from the store is usually about 4% acetic acid and 96% water. Eggshells are made up of calcium carbonate (CaCO3). The acetic acid in the vinegar reacts with the calcium carbonate in the eggshell to make calcium acetate plus water and carbon dioxide that you see as bubbles on the surface of the shell.

The chemical reaction looks like this . . .

2 CH3COOH + CaCO3 = Ca(CH3COO)2 + H2O + CO2
Acetic acid + Calcium carbonate = Calcium acetate + Water + Carbon dioxide

And there you have it…. RAINBOW BOUNCY EGGS! Have fun with this one, I know that my mini scientists did!

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