### Changing the volume available for "molecules" has an effect on how often the molecules hit the walls of their container.

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Teachable Topics:Boyle's Law

• molecular motion
• gases

Theory:

Boyle's Law says that the product of the pressure (P) and the volume (V) of a gas is a constant at a given temperature (T). In symbols...

PV = constant (for a given T)

Practically speaking, this means that if the volume of the gas decreases, the pressure must increase, and vice versa.

If the MMD is partitioned and several "molecules" are placed on one side of the partition, the molecules will move around randomly and collide with the walls of the container at some average rate. If the partition is moved to decrease the amount of space available to the molecules, the molecules will collide with the walls more frequently. Because the molecules are colliding more frequently with the walls, they exert more force (and therefore more pressure) on the walls. To summarize, a gas will have a higher pressure if it occupies a small space than if it occupies a large space.

Figure 1: Boyle's Law in action

Apparatus: