What you'll need:
- A clear glass filled with hot water
- A clear glass filled with cold water
- Food coloring
- An eye dropper
Instructions:
- Fill the glasses with the same amount of water, one cold and one hot.
- Put one drop of food coloring into both glasses as quickly as possible.
- Watch what happens to the food colouring.
What's happening?
If you watch closely you will notice that the food coloring spreads faster throughout the hot water than in the cold. The molecules in the hot water move at a faster rate, spreading the food coloring faster than the cold water molecules which mover slower.
