Teacher had a jug of hot water and a jug of cold water. We know that if you mix hot and cold water, you will get warm water. But did you ever wonder how exactly the water will mix.
Will the warm water want to go to the top or the bottom of the cold water?
Will the cold water want to go to the top or the bottom of the hot water?
Will both parts of the water just want to stay where they are?
Well, we tried this out. To make it easier to see which water is which, teacher added red food dye to the hot (well quite warm) water, and blue food dye to the cold water. Of course we got to make our predictions each time, and we got to try and explain our findings too.
Guess what happened to the red hot water in a little bottle in the large glass of cold water?…….It came gushing out of the little bottle and trying to get to the top of the glass. When the hot water cooled a little it began to sink to the bottom of the glass. It looked like a little volcano in the glass of cold water.
Now guess what happened to the blue cold water in a little bottle in the large glass of hot water?…We never expected this, but the cold water stayed where it was and didn’t budge!
Can you guess what would happen if you had two jam jars filled with water, one cold, one warm, and then you let the water mix?
Do you think it would matter if the warm water was on top or on the bottom?
What would happen to the colour of the water? Would it stay exactly as it is or would it mix to give purple water? Why/why not?
If the hot water is on top, the colours don’t mix (that really surprised us until we thought about it for a bit)
but if the cold water is on top the colours will mix because cold water wants to get to the bottom, and warm water wants to rise to the top so the colours mix and you can see the water turning purple.
Be sure to get an adult to try and help you with this at home because it’s a bit messy and warm water can be dangerous to play with.
Now we know why the water in the sea is often warmer near the surface and cooler underneath!
We love science!!!
