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Shelless Eggs

Make a bizzare, shelless, raw egg in this easy experiment.

What you need

An Egg

An egg

Vinegar

What to Do

Fill a small glass or jar with vinegar - any will work, but it might be best to use white vinegar as it is easier to see the egg.

Put an egg in, and make sure that the egg is covered with the vinegar.

Leave the egg for 24 hours.

Then have a look at the egg. Is it at all different?

What may Happen

You should find that the shell bubbles slowly in the vinegar. After about 24 hours, there will be no shell left, and the egg will become flexible and soft.

What is going on?

The eggshell is made of calcium carbonate (CaCO₃) - the same mineral as limestone. If you react a carbonate with an acid, you are left with a soluble salt, carbon-dioxide, and water. The shell slowly dissolves, producing bubbles of carbon-dioxide.

Calcium Carbonate + Acetic Acid -> Calcium Acetate + Carbon-dioxide + Water

CaCO3 + 2CH₃COOH -> Ca(CH₃COO)₂ + CO₂ + H₂O

So the only thing left holding the shell together is the membrane which keeps the liquid in the egg, which is flexible and stretchy, so the egg is flexible and squashy.

Written by Dave Ansell

Your Comments

- daveshorts - 25th Nov 09

I think you are right, the membrane is an osmotic filter, so water flows into the more concentrated solution in the egg. Many organic membranes are partially permiable to water and not salts. It is quite thick, so I have no idea how well it would work in a fuel cell though, I am also not sure if it is exactly what you want.

In a fuel cell you want charged species to be able to pass through but not uncharged ones. where as in osmosis, it is the other way around... H+ might well be small enough to get through anyway, but it isn't obvious to me.

- daveshorts - 25th Nov 09

Once the egg shell is dissolved and the egg is full of vinegar, try submersing it in corn syrup. The skin of the egg is poruous, and initially the vinegar flows in due to the concentration gradient. The pores are too small to allow the larger sugar molecules in, so the vinegar flows out due to the concentration gradient. The vinegar also changes the shape of the proteins in the egg, therefore the consistency of the egg's contents changes.

- CC - 23rd Jan 10

I am doing this for my science fair project and i also have to do a writen report on this.. on my report it asks me: what do you hope to accomplish by doing this projec and how might this project help you, your family, community, world, etc.. i need help because im not really sure how this might help me!

- Tatiana - 6th Feb 11

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Listen to this as part of the show: 8th Nov 2009 - Investigating Infertility
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