Can you get water to walk from a filled cup to an empty cup? Try out this fun STEAM experiment and find out. You will need the following items:
- Printout of the Walking Water Experiment Handout
- Small cups or glasses (three identical ones)
- Food colouring (two colours)
- Crayons or markers
- Paper towels
- Water
Experiment
Are you ready to get started? Follow the steps below.
- Grab three identical clear glasses or cups. Fill two of them with water (about halfway) and leave the third cup empty.
- Add a few drops of your favourite food colouring to each water-filled cup (pick a different colour for each cup!).
- Place the three cups about two inches apart. The empty cup should be placed in the middle.
- Take two paper towel strips and fold them until they are two inches wide.
- Place one end of the paper strip into the first water-filled cup and the other end into the empty glass. Repeat this step with the second water-filled cup.
- Monitor your experiment for about an hour. Use the handout provided to record your predictions, observations and results.
Predictions and Observations
What do you think will happen to the water? Will it stay in the cups or will it move? Record your predictions in the handout using crayons or markers.
Monitor your experiment every 10-15 minutes and record your observations. Has anything changed? What has happened to the water? Record your observations in the handout.
After about an hour, record your final results. What actually happened? Did the water move? Is the middle cup still empty? Do your results match your prediction?
The Science Behind It
How does the water get into the empty cup? Is it magic? No – it’s science! Water moves from the filled cup to the empty cup through a process called capillary action. This involves cohesive forces and adhesive forces. Cohesion is the ability of ‘like’ molecules to stick together while adhesion is the ability of dissimilar molecules to stick together.
Water molecules have strong cohesive forces and can form hydrogen bonds with one another. Under some circumstances though, water molecules prefer to stick to other types of molecules. In our experiment, the adhesive force between the water and the paper towel is stronger than the cohesive force inside the water itself. This means that water molecules are more strongly attracted to the paper towel than to each other. Because of this, the paper towel will ‘pull’ the water up against gravity, allowing it to ‘walk’ to the empty cup.
Share
Did you have fun with this experiment? Share your results with us @sci_rendezvous on Facebook, Instagram and/or Twitter. You can also use the hashtag #SciRen!
