PressureSection 16.3

The Atmosphere Gases in the atmosphere-oxygen, argon,

carbon dioxide, nitrogen, hydrogen, water vapor, some other elements

Gravity holds particles in. Particles have mass

Earth’s Atmosphere Troposphere- from 0 to 10 km-

the layer that we live in every day

Stratosphere- from 10 to 50 km-contains the ozone layer

Mesosphere- from 50 to 85 km- the coldest layer

Thermosphere- from 85-500 km-auroras form here

Exosphere- beyond 500 km- very hot- region where the Hubble Space Telescope orbits

Pressure Pressure = F/A

Units: F = newtons (N) A = m2 P = kPa

Air causes expansion because: air particles collide with the walls of their container, forcing the walls outward

More air added to container without flexible walls = more pressure

Pressure of gas- # of times the particles strike the walls of the container

Pressure When containers expand- pressure

decreases because particles don’t collide with walls of the container more often

Boyle’s Law-If volume decreases, pressure of the gas will increase

Helium balloon-as it rises, pressure decreases, allowing the volume to expand until the balloon ruptures

Pressure, Volume, and Temperature Boyle’s Law-P1V1= P2V2

Temperature & amount of gas must be constant

Aerosol cans-when heated, gas hits walls more often, pressure increases, can explodes

Charles’s Law-volume of a gas increases with increasing temperature provided the pressure does not change Reason-hotter = particles move faster = hit walls more

often, forcing walls outward

Charles’s Law V1/T1=V2/T2