Toy Boat Experiment

Procedure

Fill a sink or any container with fresh, clean water.
Now, cut out some cardboard or heavy paper in the shape of a boat.
Make your boat small, about the size of a postage stamp.
Once your boat is cut out, make a small notch in the back.
Put a small dab of soap in the notch.
Set your boat in the water and watch it speed around!

Scientific Principle at Work
Your cardboard boat with a dab of soap will demonstrate how molecules interact in solution, reducing surface tension and propelling your boat across the water. This is an important principle of chemistry. Surface tension represents the way liquids, like water and vegetable oil, act when they are mixed together. Surface tension is measured by scientists in a unit called “dynes” per centimeter. Tension is created by the attraction of molecules toward the interior.

Soap has molecules that are designed by chemists to dissolve in water. The action of dissolving reduces surface tension mixing soap molecules among the water molecules on the surface of the water. As the soap dissolves in the water, it creates a force that moves the boat forward.

In order to view some information, you will need to download Adobe Reader.

Water-based paint, soaps and other cleaners, and even makeup are made possible by the principle of reducing surface tension you’ve seen in this experiment.