Make an egg
What you need:
- Hard-boiled egg (ask an adult to hard-boil an egg for you)
- Clear container - a jar or glass
- Tap water
- Lots of salt
Fill your container nearly to the top with tap water.
Put your hard-boiled egg gently in the water. What happens? Does
the egg sink or float?
It should sink! How will you get your egg to
float? Have a think and then watch this video:
To get your egg to float, you need to put lots of salt in the
water. Stir the water to mix the salt in and watch your egg float
to the top!
To try a cool trick, pour the water out of your jar. Rinse the
jar out and half fill with tap water. Mix in lots of salt. Then,
gently add fresh tap water into the jar to fill it to nearly the
top. If you add the water gently, the layers of water won't mix.
You can drop your hard-boiled egg in and it will sink to the bottom
of the first layer, but float on top of the salt water!
The egg is denser than tap water, so it sinks. Adding salt water
to the water makes the water denser than the egg. This causes the
egg to float!