Charles’s law is one of three gas laws that explain approximately how the pressure, temperature, volume, and the number of particles in a container of gas are related. The other two laws are Boyles’s law and Avogadro’s law.
Charles’s law states that, each time the temperature of a gas rises by a given amount, the gas expands by the same fraction of its original volume. More precisely, the ratio between the volume (V) of a gas and its absolute temperature (T) remains constant if the pressure does not change. An absolute temperature is measured from absolute zero, the lowest possible temperature. Scientists measure absolute temperatures in metric units known as kelvins. The symbol for kelvin is K, and a temperature difference of 1 K is exactly the same as a temperature difference of 1 degree Celsius.
The following equation expresses Charles’s law: V</i> = constant. This equation contains no symbol for the pressure of the gas, but the equation is true only if that pressure remains constant. The equation shows, for example, that when a gas is heated from 300 K (near room temperature) to 600 K, its volume doubles. Charles’s law was discovered in 1787 by the French chemist Jacques Alexandre Cesar Charles. He found that carbon dioxide, hydrogen, oxygen, and nitrogen all expand at constant rates as their temperatures rise. The French chemist Joseph Gay-Lussac performed similar experiments and published his results in 1802. As a result, Charles’s law is sometimes called Gay-Lussac’s law.
