Kinetic Theory Gases are composed of SMALL, SEPARATE particles called MOLECULES. Gas molecules are in CONSTANT MOTION All COLLISIONS between particles are PERFECTLY ELEASTIC The MOLECULES of a gas display no ATTRACTION or REPULSION for one another.
Kinetic Theory The AVERAGE KINETIC ENERGY of the molecules is DIRECTLY PROPORTIONAL to the KELVIN temperature of the gas.
Ideal Gas • Gas whose BEHAVIOR conforms to the KINETIC THEORY -it is THEORETICAL. Real Gas • Particles in a real gas… • Have their own volume • Attract each other • Gas behavior is most ideal… • At low pressures • At high temperatures • In nonpolar atoms/molecules
Characteristics of Gases • Gases expand to fill any container • Random motion, no attraction • Gases are fluids (like liquids) • No attraction • Gases have very low densities • No volume = lots of empty space • Gases can be compressed • No volume = lots of space • Gases undergo diffusion & effusion • Random motion
Factors Affecting Behavior of Gases • Pressure • Volume • Temperature • Number of moles
Gas Pressure: Pressure = FORCE ÷ AREA = ____ atm Atmospheric Pressure - the PRESSURE the earth’s ATMOSPHERE exerts due to its WEIGHT. Barometer: Instrument used to measure ATMOSPHERIC PRESSURE Invented by TORRICALLI
Key Units 101.325 kPa (kilopascal) 1 atm 760 mm Hg 760 torr 14.7 psi 101.3 kPa = 1 atm = 760 torr = 760 mm Hg
Standard Temperature & Pressure 0°C273 K 1 atm101.325 kPa -OR- STP
K = ºC + 273 ºF -459 32 212 ºC -273 0 100 K 0 273 373 Temperature • Always use absolute temperature (Kelvin) when working with gases.