I. Physical Properties Gases Gases
A. Kinetic Molecular Theory b Particles in an ideal gas… have no (very small) volume. have elastic collisions. are in constant, random, straight- line motion. don’t attract or repel each other. have an avg. KE directly related to Kelvin temperature.
C. Characteristics of Gases b Gases expand to fill any container. random motion b Gases are fluids (like liquids). b Gases have very low densities. lots of empty space
C. Characteristics of Gases b Gases can be compressed. lots of empty space b Gases undergo diffusion & effusion. random motion
D. Temperature b Always use absolute temperature (Kelvin) when working with gases. ºF ºC K K = ºC + 273
E. Pressure Which shoes create the most pressure?
7 Atmospheric Pressure b Atmospheric pressure b is the pressure exerted by a column of air from the top of the atmosphere to the surface of the Earth. b Copyright © 2009 by Pearson Education, Inc.
E. Pressure b Barometer measures atmospheric pressure Mercury Barometer Aneroid Barometer
E. Pressure b Manometer measures contained gas pressure U-tube ManometerBourdon-tube gauge
E. Pressure b KEY UNITS AT SEA LEVEL kPa (kilopascal) 1 atm 760 mm Hg 760 torr 14.7 psi
F. STP Standard Temperature & Pressure 0°C 273 K 1 atm kPa -OR- STP
G. Volume b Volume- The space occupied by the gas. They have an indefinite volume, they will fill any container. b Units of measure: L liter or ml milliliter b At STP, one mole of gas occupies 22.4 L of volume