Giant Green Eggs!

Using your Store Cupboard Science knowledge you can turn a normal egg into a giant green egg!

How we did it – follow these instructions with Morgan and Tilly

We checked our egg. It’s a normal egg!

We placed the egg into a jar and covered it with white vinegar.  We turned the egg a few times so that the vinegar made contact with all the surfaces of the eggshell. If the egg floats in the vinegar then place a spoon over the top .  We left the egg in the vinegar for 24 hours.

When we took the egg out of the vinegar the shell had completely dissolved! We patted the egg dry with kitchen paper.   If you drop the egg from a height of no more than 5 cm will bounce – remember our rubber egg Store Cupboard Science experiment about milk, eggs and a minty geyser! –

We took a bigger glass jar and put sugar at the bottom, then we placed the egg onto the sugar and put more sugar over the egg until it was fully covered.  You need to leave the egg in the sugar for at least 36 hours.

We removed the egg and placed it on a saucer.  We pressed on the egg gently with the back of a teaspoon and it dented but didn’t break the surface

We filled another clean glass jar with just enough water to cover the egg and with a bit more on the top.  We then added green food colouring to make the water turn a strong green colour.

We washed the egg gently to make sure no more sugar remained on it and then added the egg to the green water.  It was then left for 24 hours.

We took the egg out with a spoon to see how the egg had changed.  We compared the egg with a normal egg – look at the difference in size!

The Science Bit:

This experiment  uses science in two ways: showing how materials change by using the processes of dissolving and by osmosis.

Vinegar is acidic and the shell of an egg is chalk (calcium carbonate).  The acid in the vinegar dissolves the calcium carbonate.  After 24 hours the eggshell has dissolved which leaves the rubbery inner of the egg behind, so when you gently drop the egg it bounces!

As we have seen in other experiments, some chemical reactions can be reversed but some cannot. Dissolving calcium carbonate can’t be reversed as we cannot recreate the eggshell around the egg so once we have dissolved the eggshell in the vinegar we can’t get it back.

By placing the egg in the sugar, the egg feels saggy and can be dented. We made a dent in the egg with the back of a spoon.  Eggshells protect the egg from losing water, but now we have dissolved the shell, the egg loses water by osmosis, leaving it a saggy egg!

The water that comes out of the egg turns the sugar in the jar into syrup.

The sugar has drawn out most of the water from the egg (by osmosis). By placing the egg into the green-coloured water, the water soaks into the egg by osmosis and the egg now swells to become a giant egg!  The food colouring molecules also pass into the egg, making it turn green.