What happens to the volume of gas if the pressure decreases at constant temperature?

When the pressure of a gas decreases at constant temperature, the volume of the gas increases. This relationship is described by Boyle's Law, which states that for a given mass of gas at constant temperature, the product of pressure and volume is a constant (P1V1 = P2V2).

When the pressure is lowered, to maintain this constant relationship, the volume must increase. This can be explained conceptually: as the pressure decreases, gas molecules experience less force per unit area on the walls of the container, allowing them to spread out more, thus increasing the volume they occupy.

In a real-world scenario, consider a syringe. When you pull back on the plunger, you reduce the pressure within the syringe, which allows the gas inside to expand and occupy a larger volume. This behavior aligns with Boyle's Law and clarifies the direct relationship between pressure and volume of a gas at constant temperature.