 Welcome to the Boyle's Law video presentation. During the 17th and 18th century, scientists established a variety of laws that pertained to the interactions of pressure, volume, and the temperature of gas. One of these laws is called Boyle's Law, and it states, The absolute pressure of a confined gas is inversely proportional to its volume. This law only applies if the temperature to which the gas is exposed remains constant. This means that if the gas's pressure or volume changes, the other variables will also change. There are two variations of Boyle's Law that we'll be covering in this presentation. A change in pressure exerted on a given quantity of gas causes an inverse effect on its volume. A closed container is shown. It has no external pressure pushing down at the piston other than the atmospheric pressure of 14.7 psi or one atmosphere. The volume of the entrapped air is one liter. The pressure of the entrapped air measured by the gauge as 14.7 psi is always equal to the pressure exerted on the piston. If the external pressure on the piston is doubled to two atmospheres or 29.4 psi, 2 times 14.7 psi equals 29.4 psi. The entrapped air inside the container will compress to 0.5 liters or half the original volume. The pressure reading for the entrapped air has increased to 29.4 psi. This animation illustrates why the pressure varies as the volume changes. If the gas is compressed, the molecules crowd closer together, which causes more molecular collisions with the container walls, resulting in an increase of pressure. Observe how changes in volume affect pressure. Now, we'll be covering the second variation of Boyle's law. A change in the volume of air will cause an inverse effect on the pressure it exerts. A one liter tank, which holds compressed air at 2 atm of pressure, is shown. When the air is released by opening the valve, it escapes into the balloon until the pressure equalizes at 14.7 psi. The volume of air increases from 1 to 2 liters, 1 liter inside the tank, and 1 liter inside the balloon, as the pressure reduces to half. Congratulations! You have completed the Boyle's law video presentation.