Your body is making use of Boyle s law, like so many chemical principles, right now. When you breathe, a muscle in your lower abdomen called the diaphragm, contracts and increases the volume of your chest cavity and lungs. The increased volume means the air in your lungs is at lower pressure, lower than atmospheric pressure, so air from outside your body rushes in. In the reverse process, the diaphragm relaxes, reducing the volume of your lungs and causing you to exhale. Another way to change the volume of a gas is to alter the temperature.
Gases expand when heated and contract when cooled.
Today, sitting with his dogs in the opposite corner of the room, another important property of gases occurs to Chem1A-man. In short, lighter molecules diffuse faster than heavier ones. Aside from explaining the migration of suspect gases through a room, Graham s law differs in another important way from Charles and Boyle s laws. Graham s Law requires we know something about the gas particles themselves. Charles and Boyle s Laws make no assumptions about the microscopic properties of the gas at all.