14.1. Gas Properties http://www.ck12.org
FIGURE 14.3
When gas is pumped into a closed rigid
container, the pressure increases. If the
number of gas particles is doubled, the
pressure doubles.amount of gas in the canister. Since the canister cannot expand, the increased number of air molecules will strike the
inside walls of the canister twice as frequently as they did before. The result is that the pressure inside the canister
doubles. As you might imagine, if more and more air is continually added to a rigid container, it may eventually
burst. Reducing the number of molecules in a rigid container has the opposite effect, and the pressure decreases.
The air in a fully inflated car tire is at a higher pressure than the air outside the tire. What happens if you press on
the tiny valve stem of the tire (Figure14.4)? You hear the distinctive hissing noise as the air rushes out of the tire.
A gas will move from an area of higher pressure to an area of lower pressure until the pressures are equal. If you
continue to press on that valve stem, the tire will eventually go flat.
FIGURE 14.4
Don’t press on the valve stem of a tire
unless you want the air in the tire to
escape!