Science Experiments

Which Mixes Colors Faster, Hot or Cold Water?

By: Highlights Editorial
A glass of water with coloring beginning to swirl in it.
minute activity
Ages 3+
Critical Thinking
Fine Motor Skills

It’s interesting to watch a few drops of food coloring spread in liquid. But does the liquid’s temperature change what happens? Which mixes colors faster, hot or cold water? Let’s find out. Like any good scientist, though, make a guess about what will happen before you start the experiment.

Which mixes colors faster, hot or cold water?

What You'll Need

What to Do

  1. Set the two glasses on a countertop.

  2. Place an ice cube in one of the glasses.

  3. Put a drop of red food coloring in each glass.

  4. Watch how the color moves through the water in both glasses.

How It Works

Did you notice that the color moves faster throughout the water with the ice cube? That’s because cold water from the melting cube is denser than the warm water around it. As the cold water sinks, it creates a downward current. That forces warm water to flow upward from the bottom, and the two kinds of water begin to mix. Those currents quickly mix the color into the water.

Extend the Fun

Younger kids: Play with the number of ice cubes in the cup. Add another ice cube when the first cube has nearly melted. Then try two. Experiment with putting the drops in at different times. See what happens when you use different colors at different times in the process. Can you make two colors mix themselves together?

Older kids: Make colored ice cubes, and then repeat the experiment. Take pictures of what’s happening at each step. How is the experiment the same and how is it different compared to the first version? What do you notice about the way the color from the ice cube infuses the water?

Whether to the pool, the playground, Grandma’s house or on vacation, you’ll find plenty of summer fun for kids. From hands-on summer activities for kids to their new favorite summer shirts and fun travel games to take along … let’s go summer!

Author Photo
By: Highlights Editorial