This is a set of experiments that can be done with just a few eggs and some basic kitchen ingredients, like vinegar and salt. They are fun to do, but there is some interesting science behind them, too.
The first two experiments take a few days, so you may consider starting them both off together so that you can observe and compare the results.
You will need a few items that are not in the Starter Kit:
Place the egg in the jar and pour in enough vinegar to cover it completely.
Leave it in a safe place, uncovered. The process takes a few days. Examine the egg each day and record what you see:
You will also need to refresh the vinegar in the jar every second day. Just pour out the vinegar carefully without damaging the egg and pour in some fresh vinegar.
If all goes well, in a few days, you will see that the egg has changed colour. The shell has disappeared leaving the slightly transparent inner membrane intact! You should be able to see the yolk inside it too.
The Egg reacting with the Vinegar
The shell of the egg is made of a substance called Calcium Carbonate. It reacts with the vinegar which contains an acid (Acetic acid) and forms Calcium Acetate, Water and Carbon Dioxide.
The bubbles you may have noted are Carbon Dioxide. They float up and escape into the air. The water remains in the jar and the acid in the vinegar gets used up. That is why you need to refresh the vinegar until the egg shell is fully dissolved.
You may also have noticed that the egg seems to have got bigger. That is because some of the liquid in the jar has got into the egg through the membrane. This is a process called Osmosis that we may investigate in other experiments.
For those of you who may be interested in the chemical reaction and the symbols, this is the reaction:
Acetic acid (Vinegar) + Calcium Carbonate (Egg shell) → Calcium Acetate + Water + Carbon dioxide
2CH3COOH + CaCO3 → Ca(CH3COO)2 + H2O + CO2
This experiment is similar to the first one, but you need a boiled egg rather than an uncooked one.
You will need:
Now place the egg in the jar and pour the vinegar over it as before.
Keep the jar in a safe place and observe daily, changing the vinegar every second day.
Note down what you see. The process will take about one week to complete.
At the end of a week, you should see that the shell has dissolved and that the egg seems to have grown bigger. Take the egg out of the jar and carefully dry it with a paper towel.
You will notice that it feels different to a normal boiled egg. It should have a more flexible "bouncy" feel.
Try dropping it on a hard surface, like a dinner plate, from a height of about 20-30 Cm (not more, or it will split - it is not that strong!). Note down what you see.
Now try comparing it with a freshly boiled egg that has been shelled. You can even try dropping both from the same height to compare how they behave.
In this experiment you will be able to identify which egg is hard boil compered to raw egg without cracking them.
A raw egg
A hard-boiled egg
A smooth table top
1. Label the hard-boiled egg with a H. Label the raw egg with a R.
2. Spin raw egg on the table top.
3. Spin hard-boiled egg on the table top.
4. Observe which egg spins fastest and longest and record.
5. Spin both eggs again on the table top.
6. Try to stop them by putting your finger on them lightly.
7. Observe which egg stops easily and record.
The hard-boiled egg should spin longer and easy to start spinning and easy to stop spinning as hard-boiled eggs are solid inside. When you try to stop the raw egg, it keeps spinning as the liquid inside the raw egg, still slides because it is liquid. When you try to stop raw egg it only stopped the shell, but the liquid inside which causes the shell to keep spinning.
A hardboiled egg is solid inside whereas a raw egg is liquid. When you spin the raw egg, its centre of gravity changes as the liquid inside the egg moves around, resulting in the vibrant motion in the raw egg. When raw egg starts spinning, you can stop it briefly with your finger however when you take your finger away quickly, the egg will continue to spin for a second. This is due to the continuous motions of the liquid inside the egg are still moving. When the hardboiled egg is spun, the solid centre immediately moves with the shell together and when you stop it with your finger shell and hard material inside the egg stopped together.
Just like the first experiment, the Calcium Carbonate in the egg shell dissolved in the vinegar, leaving the membrane and the boiled egg inside.
But the liquids also got into the egg and changed the consistency of the egg inside. That is why it looks bigger and feels different. It can actually bounce!
This is a simple experiment that can help you distinguish a raw egg from a boiled one, without cracking them!
You need a boiled egg and a raw egg.
(Please get an adult to help you boil the egg)
A boiled egg is solid inside. It has a stable shape and weight distribution. So it should start spinning easier and continue to spin a little longer.
The raw egg is liquid inside. The liquid tends to move around and won't let the egg spin evenly. It is therefore likely to stop earlier as well.
But when you try to stop them, it's a bit different. You will find the raw egg will stop under the pressure of your finger, but if you let it off, it will try to spin a little more! This is because the liquid inside is still spinning even when the egg seems to be stationary.