MAKE YOUR OWN THERMOMETER

Building your own thermometer is really simple. This experiment will show you how a simple thermometer works.

Materials:

Access to tap water
Rubbing Alcohol (Do Not Drink!!)
1 - Clear plastic bottle with a narrow neck
1 - Bottle Food Coloring (Any Color)
1 - Clear Plastic Drinking Straw
Some Modeling Clay

Procedure:

1) Carefully pour equal portions of tap water and rubbing alcohol into the bottle, filling about
    one quarter of the bottle.

2) Add a couple drops of food coloring and gently stir the mix.

3) Put the straw in the bottle, but don't let the straw touch the bottom of the bottle.

4) Use the modeling clay to seal the neck of the bottle and hold the straw in place.

5) Hold your hands on the bottle and watch what happens to the liquid in the bottle.

6) Put the bottle on a table and remove your hands. What what happens to the liquid now.

What's Going On?

    Just like any thermometer, the mixture inside the bottle expanded when it was warmed and compressed while it was cooled. This change made the liquid no longer fit in the bottom of the bottle. As the alcohol expanded the colored mixture moved up through the straw. If the bottle were to get very hot, the liquid would rise to the top of the straw and eventually overflow. The opposite is true for cooling.
    If you leave the thermometer on a desk or counter for a day or two, you will notice how the liquid changes as the temperature changes throughout the day.  
    This thermometer will not be able to tell you what the temperature is, but you'll get the idea of how a thermometer works during this experiment.

HOME