Making naked eggs (where you remove the outer shell of an egg without breaking the egg) is a simple and fun science experiment you can easily do, using just three things you can find in the kitchen. An egg, lemon juice or vinegar and a pot or cup.
Egg are made up of several parts, there is the shell which is porous and lets air and moisture in, inner and outer membranes which protect the egg from bacteria, an air pocket and the egg white which provides cushioning and shock absorbance and the egg yolk which contains all the nutrients a little chick needs to grow.
The shell of the egg is made from calcium carbonate crystals. And the inner and outer membranes are made up of keratin which is a substance that gives makes your hair and nails so strong. If you touch and feel an empty egg shell you can see the outside of the shell is rough and the inside where the membrane is, is smooth.
The calcium of the shell will dissolve easily in acid over a short period of time where as the keratin of the membrane won’t. This means you can dissolve the outer shell of the egg and leave the inner membrane and contents of the egg whole and unbroken.
All you need to dissolve your egg shell is a pot or cup to place your egg in and enough lemon juice or vinegar (as the acid) to cover and surround the egg with. Then simply leave it all on the side for a day or two to give the acid time to dissolve the shell.
You can try experimenting with both lemon juice and vinegar. We found the lemon juice was more effective in removing the egg shell and also smelt much nicer. As the egg shell dissolves ask the children observe what’s happening (older children can take notes). Can see the shell coming away from the egg? Are there any bubbles?
When you think the egg is ready remove it from the pot and carefully and very gently scrape away any remaining shell. (You can always put it back in the pot if it needs longer). Then rinse off the remaining acid with water. Voila you have a naked egg.
It should be slightly translucent so if you hold it up to the light you can see the yolk in the centre. Did you know the yolk is anchored to the shell by strings of egg white called the chalaze? You can see them sometimes when you crack an egg open.
The outer membrane of the naked egg is quite strong and supple, it makes the squishy and bouncy. You can gently squeeze it and experiment with dropping it from short heights to see how much it bounces. Just beware the membrane can break if when you drop it or handle it too roughly, and its very messy, so it’s best to play with it over a container or outside.
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