HEL In one or two sentences, describe a scenario using the combined gas law in which changes occur in the pressure and temperature of an enclosed gas but the volume does not change.

The combined gas law combines the three gas laws: Boyle's Law, Charles' Law, and Gay-Lussac's Law. It states that the ratio of the product of pressure and volume and the absolute temperature of a gas is equal to a constant. When Avogadro's law is added to the combined gas law, the ideal gas law results. Unlike the named gas laws, the combined gas law doesn't have an official discoverer. It is simply a combination of the other gas laws that works when everything except temperature, pressure, and volume are held constant.

As volume decreases, the pressure increases. In this case, squeezing the bottle reduces the volume. However, the volume in which the particles bounce around in is decreasing, therefore the number of collisions between the particles and the inner surface of the water bottle increases. The pressure the gas exerts on the inside of the bottle is greater than the pressure exerted on the bottle by the outside air. When the hot air is cooled, the gas particles slow down and the volume of the gas decreases.