Question

Describe a simple experiment to illustrate that molecules are not at rest but they constantly move

Answer 1

What you need

Two glasses, about the same size2 dark colors of food coloringWarm and cold water

What to do

Put the two glasses next to each other. Pour cold water into one glass until it is about ¾ of the way full. Then pour warm water in the other glass up to the same level.Take a dropper of food coloring in each hand and add two drops of food coloring to each glass at the same time.Watch how the food coloring spreads through the glasses. Which glass does it spread through faster?

What's going on

You should notice the food coloring in the warm water spreading out faster than the food coloring in the cold water. If you didn’t observe this, try making your cold water a little colder and your warm water a little warmer. Also make sure you add the food coloring to each glass at the same time.
Warm water has more energy than cold water, which means that molecules in warm water move faster than molecules in cold water. The food coloring you add to the water is pushed around by the water molecules. Since the molecules in warm water move around faster, the food coloring spreads out quicker in the warm water than in the cold water.