Heat, Volume, and Density

In 1717, a man named Gabriel Daniel Fahrenheit invented the thermometer. He discovered that he could use mercury, a fluid that would expand and contract based on temperature, inside a very thin glass tube to measure temperature. When the liquid in the tube is heated, the molecules get excited and the liquid goes up. When the liquid is cooled, the molecules aren't as active and the liquid goes down.

We made a home-made thermometer out of clear tubing, a glass bottle, blue water, some wire, and hot glue. Here is the video we made:



After we used the thermometer, we put it in a paper bag and froze it to see what would happen. The next day, when we opened the freezer, the bottle was cracked, and the ice was jutting out of the bottle!

Here's what it looked like:





So water expands when it's heated and when it's cold. How can this be? When the water in our bottle thermometer was heated, the water molecules became more energetic spread out, moving the water up the tube. When water cools, the molecules lose energy and move closer together. The water in the tube goes back down. When we put the bottle in the freezer, the water kept contracting until it reached 4 degrees celsius. Between 4 and zero degrees celsius, the water becomes solid, and the molecules expand into a more solid pattern. The ice expanded enough to break the glass bottle!