temperature+and+pressure

The kinetic molecular theory defines temperature and pressure in terms of gas behaviors.

//Temperature// is defined as the average kinetic energy of a sample of gas molecules.
 * The higher the temperature, the larger the gases' kinetic energy (the faster they will move).
 * Try some of these [|demonstrations] to see how temperature affects the speed of a sample of gas molecules.

//Pressure// is defined as the force exerted on a surface by collisions with gas molecules.
 * What happens when you put your hand out the window while in a moving car? The gas molecules in the air are colliding with your hand and will exert a force, pushing on your hand. The more surface area you provide, the greater the force on your hand.
 * Try these [|demonstrations] to explore some gas pressure concepts.



Gas pressure units come in a wide variety. The metric base unit is the //atmosphere// (atm) and is the average pressure exerted by the Earth's atmosphere at sea level, designated 1.00 atm.

All other units can be related to the atmosphere.

1.00 atm is equal to:
 * 14.7 psi (pounds per square inch, used in the English system. Car and bike tires use psi.)
 * 760 mm Hg (millimeters of mercury, used in old barometers.)
 * 29.92 inches Hg (inches of mercury)
 * 760 torr
 * 1.01325 bar (used for metric atmospheric pressure units)
 * 101,325 pascals
 * 101.325 kilopascals

Here is a worksheet for practicing gas pressure unit conversions:

Atmospheric pressure is measured using a [|barometer]. Old barometers consisted of an evacuated tube, closed on one end, with the open end immersed in mercury. As pressure changed, the mercury level changed (high pressure caused it to rise, for example).