2.26. Charles’ Law http://www.ck12.org
2.26 Charles’ Law
- Describe how the volume of a gas is related to its temperature.
- Explain what happens to gas particles when they are heated.
In the 1700s and 1800s, hot air balloons were very popular. Why wouldn’t they be? Riding in a hot air balloon
allowed people to travel through the air and get a bird’s eye view of the landscape at a time when airplanes did not
yet exist. Do you know why hot air can inflate a balloon? Read on to find out.
Up, Up, and Away
The popularity of hot air balloons got scientists thinking about gases and what happens to them when they heat
up. In the early 1800s, two French scientists—Jacques Charles and Joseph Gay-Lussac—decided to investigate
how changes in the temperature of a gas affect the amount of space it takes up, or its volume. They heated air and
measured how its volume changed. The two scientists already knew that the pressure of a gas affects it volume.
This had been demonstrated back in the 1660s by the English scientist Robert Boyle. So Charles and Gay-Lussac
controlled the effects of pressure by keeping it constant in their experiments.
Based on the results of the research, Charles developed a scientific law about gases. It is one of three well-known
gas laws, the others being Boyle’s law and Amontons’ law. According toCharles’ law, when the pressure of a gas is
held constant, increasing its temperature increases its volume. The opposite is also true: decreasing the temperature
of a gas decreases it volume.
You Try It!
At the URL below, you can simulate Charles’ and Gay-Lussac’s work. The simulation lets you choose different
temperatures for a gas and see how it affects the volume of the gas. After you have recorded several sets of values in
the data table, use the graphing feature to plot the points.