Thermal expansion occurs when the volume of matter changes as result of an increase or decrease in temperature. Normally, matter exposed to heat expands, since the matter's participles move rapidly and separate. Conversely, matter exposed to colder temperatures normally contracts. Different science projects demonstrate and test thermal expansion.
Observe thermal expansion by creating a heat detector from normal household items. For the experiment, use a block of wood, a push pin, a rubber band and a piece of cardboard. First, stretch the rubber band around the block of wood. Cut an arrow from the piece of cardboard and attach the arrow to wood by pushing the push pin through the cardboard, the rubber band and the piece of wood. Light a match and hold the match near the rubber band on the right side of the arrow. Observe the cardboard arrow spin counterclockwise. Move the match to the other side of the arrow and hold near the rubber band. Observe the arrow spin clockwise. This experiment demonstrates that rubber contracts under heat and expands under cooler temperatures.
Compare the varying degrees of thermal expansion in different gases. Fill rubber balloons with different gases, including helium, nitrogen, carbon dioxide, oxygen and argon. Immerse each balloon into a tank of water and measure with a graduated cylinder the amount of water that is displaced by expansion of the balloon as it expands when water is drained. Keep the type of balloon, the amount of water in the tank and the size of the balloon constant. Perform the experiment using different water temperatures.
Gas Versus Liquid
Observe how hot thermal expansion affects liquids differently than gases. Inflate a rubber balloon and tie a knot to close it. Light a match and hold the match a few inches below the balloon. Within a few seconds, the balloon will expand since the gas inside expands under heat. Next, inflate a balloon partially and then add water to the balloon. Tie the balloon shut with a knot and hold over a lit match. The balloon will not pop, since the water absorbs the heat and does not expand the gas.
Observe thermal expansion in a jumping coin. Fill a large container with cold water, approximately 40 degrees Fahrenheit. Dip a glass soda bottle into the water so the bottle is almost submerged, with the opening above the surface of the water. Avoid allowing any water into the bottle. Place a coin that is slightly larger than the bottle opening on the mouth of the glass bottle. With both hands, hold the body of the bottle and observe the action of the coin. The coin will bounce and jump as a result of thermal expansion. The heat of your hands changes the volume of particles inside the bottle.
- Photo Credit Photos.com/Photos.com/Getty Images