1. 13.1: Nature of Gases

2. Kinetic Theory States: 1. all matter is composed of small particles
2. the particles are constantly moving

3. Gases & Kinetic Theory
Particles are small, hard spheres with an insignificant volume
a. Particles are far apart
b. No attractive or repulsive forces between
them
c. Particles move independently of each other

4. Particles in the gas are constantly in rapid and random motion
a. spread out and fill their container
b. travel in straight-line paths
c. Particles will collide with each other & the walls of the container.
d. When a collision occurs, the particles bounce off in the opposite direction.

5. Collisions b/w particles are perfectly elastic.
1. Kinetic energy (KE) is transferred from one particle to another with no loss.
2. Total KE of the system stays constant.

6. Gas Pressure
Measures the force of collisions per unit of area for the particles hitting the walls of the container
Temperature
1. measures the avg. KE of the matter
2. KE = ½ X mass X velocity2
3. As temp. increases, KE inc. and speed inc.
When particles move fast, they collide with the walls of the container with more force. Therefore, the pressure (P) increases.

7. Atmospheric Pressure
Def’n: the pressure exerted on us by all the particles in our atmosphere
Occurs b/c gravity holds the particles close to the surface of Earth
At the top of a mountain, atmospheric pressure is smaller b/c there are fewer particles.
Measure with a barometer
SI unit of pressure & its relationship to atmospheric pressure and mm Hg

8. Units of Pressure SI unit: Pascal We use kiloPascal (1kPa = 1000 Pa)
1 atm = Pa = 760 mm Hg = 760 torr
Convert 450 kPa to atmospheres and mm Hg.

9. Convert 763 kPa to mm Hg.
Convert 769 kPa to torr.