Saturday, 1 March 2014

Naked Egg Science Experiment

naked egg title image

If someone asked me have I seen a "naked-egg"?, I would have thought this maybe material of an adult nature. But I'd be wrong. This is nothing triple-X, it's more triple-eggs and what's further is I'm going to show you how you can get your eggs-naked too.

Materials Needed:

  • A clear glass container 
  • Some clear vinegar/white spirit vinegar(best for seeing results)
  • Some raw eggs


raw egg in a clear glass

pouring vinegar over an egg

1. Carefully place your raw egg at the bottom of your clear glass container and fill it with enough vinegar to cover the egg. Minimise the risk of the egg cracking by not putting too much vinegar in with the egg, when the reaction starts the egg will float and sometimes descend. The less vinegar you put in, the less the distance the egg can travel up and down.

vinegar dissolving an eggs shell

2. Now observe the early results - it's going to take anywhere from 12-24hrs for the bulk of the shell to be removed. Luckily the reaction starts straight away and you can see bubbles produced which is fun to watch for awhile. A good sign of progress is the white frothy scum that appears to collect on the surface of the vinegar after awhile.

egg shell being removed by vinegar

3. After a day has passed check on the progress of our naked egg. At this point you may have noticed the outside of the egg shell looks a bit powdery, mine must have rubbed against the glass overnight as a small piece of the shell was rubbed off. Pour the vinegar away being very careful to catch the egg as it comes out - you don't want to break that membrane. 

naked egg

4. You will see the egg shell starts to rub off in your hands, I carefully rinsed mine off under a slow running cold tap to speed the process up a little. Then I poured some fresh vinegar back into the glass and carefully placed the egg back in. Leave it to stand for another 24hrs. Again checking when this second layer can be washed off (it just really speeds things up).

naked egg

After 2 days of soaking your raw egg in vinegar you should have your "nakedegg"! You should notice that your egg is larger than when you started. This is because the eggs membrane is semi-permeable and has actually allowed some of the vinegar in - this is called osmosis.

How Does It Work?

The shell of the egg is made up of calcium carbonate. When you soak your egg in vinegar (which is a 5% acetic acid solution) the acetic acid in the vinegar starts to break the egg shell down. The chemical reaction of the vinegar and egg breaks its shell into its two parts - the calcium and its carbonates. The calcium is floating free in the water, while the carbonate becomes the carbon dioxide bubbles that you can see on the egg shell.

CaCO3 (s) + 2 HC2H3O2 (aq)   →   Ca(C2H3O2)2 (aq) + H2O (l) + CO2 (g)
(Egg shell)          (vinegar)                        (frothy scum)        (water)    (bubbles on egg)

Things To Do With A Naked Egg

  • Shine a light through it to see the yolk floating around inside.
  • Explore osmosis further by sitting your naked egg in some water that you've mixed food colouring in. You will see your naked egg has took on a new colour, but it's not just stained the outside. This colouring is inside the egg and can be viewed sloshing around inside the egg when you move it.
  • Your new naked egg has a rubber like texture and can bounce. Just let it dry a bit so the membrane isn't too weak and remember not to let it bounce from too high unless you want egg everywhere. I'd advise you do this somewhere you don't mind the egg contents spilling out.
For more fun with eggs check out our Easy Way To Separate Eggs article.

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