Temperature and Water Density Science Experiment

Science experiment fun is the best, fun way to learn. And a fun activity to do outside in the beautiful spring weather. The perfect thing to do this time of year is to spend time outside. This temperature and water density science experiment is the perfect experiment to take outside.

Temperature and Water Density Science Experiment

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When you are stuck home and bored, you do science experiments that you have always wanted to try but always figured would be a huge mess. But again, bored means just doing it no matter what.

This science experiment is easy to do, but does pose the risk for making a mess. Embrace it, or go outside where you won’t worry about the mess.

What you need:

• cold water
• hot water
• two Mason jars
• food color
• index card

What you need to do:

1. Fill one jar with cold water and add food color.
2. Fill the other jar with the hottest water you can while still being able to touch the jar. Add a different color of food coloring to the water.
3. Place the index card over the opening of the color water jar.
4. While holding the index card in place flip the jar over and on top of the jar of hot water.
5. Quickly remove the index card and watch what happens.
6. Redo the experiment but instead placing the jar of hot water on top.

Scroll down to find a printable version of the directions.

How to Do this Temperature and Water Density Experiment

I had a towel under the jars because I was prepared to make a huge mess. I was fully expecting the whole jar of cold green water to pour everywhere. BUT I was surprised with only a few drops of water being spilled.

Thanks to my school supply stash, I had everything for this science experiment including the index cards. I placed an index card on the top of the jar of cold water, holding it in place, I quickly flipped it over on to the top of the jar of warm water, and pulled the index card out from between two.

You will see the warm water on the bottom quickly rise and mix into the cold water. The cold water jar on the bottom, barely mixes with the warm water on top.

What’s Happening

The molecules in hot water move faster than those in cold water. Hot water molecules bounce around and leave gaps. This makes hot water slightly less dense than cold water.

Cold water on the bottom, the denser cold water stays there.

Cold water on the top, heat molecules rise. 

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