Egg in vinegar
This experiment is so easy to do, but the kids love it and it’s great science too. Simply take an egg (raw) and place it into a glass. Completely cover the egg in vinegar. Observe that the egg shell gets a lot of bubbles on it when it is placed in the vinegar. This is because the egg shell is made of calcium carbonate and this reacts with the acetic acid in the vinegar to form carbon dioxide. Now leave the egg in the glass of vinegar for 48 hours.
After 48 hours, take it out and wash it in some tap water. Get your child to feel the egg – it should feel very soft rubbery because the shell has now dissolved. It should also look bigger (compare to another egg if needs be). This is because with the shell dissolved, water is able to move through the semi-permeable membrane of the egg via osmosis.
Next comes the fun part. Testing out how bouncy your new rubbery egg is! Encourage your child to start with the egg just a little way above the work surface and then keep testing out greater heights. Eventually the egg will break as the membrane is quite thin. My preschooler would quite happily do this every day – he loves it!