ATLANTA — As the weather warms up this spring, this is an easy way for kids to visualize how measuring temperature works.
What is temperature?
Temperature is the average kinetic energy of a gas, in this case, air. The warmer the temperature, the greater the energy of air molecules - or their "speed," if you will.
So that number on the thermometer that tells you the temperature is actually the average "speed" of molecules moving around in the air based on the Fahrenheit scale.
Generally, the more kinetic energy a liquid or air substance has, the more it will expand or take up more space.
The experiment: Make your own thermometer
In this experiment, we will use a water and alcohol mixture to measure the temperature. The warmer the temperature, the greater the kinetic energy, causing the solution mixture to expand as molecules bounce around freely.
- Empty bottle (using a 2-liter here)
- Clay or playdough
- Index card
- Food coloring
- Medium to long straw
- Rubbing alcohol
- In your clear bottle, mix equal parts alcohol and water.
- Put a few drops of food coloring so that the solution is visible through the straw
- Using the putty/playdough, seal the straw to the bottle opening. The straw should not be able to move around.
- Make a few lines on the index card (see picture) and tape to top part of straw just above the seal.
As the temperature around the bottle changes, the water inside the bottle will change too!
A quick way to watch this happen would be to place the bottle in warm water and watch the liquid in the straw rise! You could also place the bottle outside in the sun and watch it rise and fall slowly with time
To make your homemade thermometer accurate, you can take a meat thermometer and place it inside the straw with water and mark the water level with the corresponding temperature.
If you leave the thermometer outside this weekend, you should be able to watch the temperature change from Saturday to Sunday!
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