Presentation on theme: "III. Physical Properties Ch. 13 - Gases. A. Kinetic Molecular Theory b Particles in an ideal gas… have no volume have elastic collisions are in constant,"— Presentation transcript:
III. Physical Properties Ch Gases
A. Kinetic Molecular Theory b Particles in an ideal gas… have no volume have elastic collisions are in constant, random, straight- line motion dont attract or repel each other
B. Real Gases b Particles in a REAL gas… have their own volume attract each other b Gas behavior is most ideal… at low pressures at high temperatures in nonpolar atoms/molecules
C. Characteristics of Gases b Gases expand to fill any container random motion, no attraction b Gases are fluids (like liquids) no attraction b Gases have very low densities no volume = lots of empty space
C. Characteristics of Gases b Gases can be compressed no volume = lots of empty space b Gases undergo diffusion & effusion random motion State Changes
D. Describing Gases b Gases can be described by their: Temperature Pressure Volume Number of molecules/moles K atm L #
E. Temperature ºF ºC K K = ºC b Always use absolute temperature (Kelvin) when working with gases!
F. Pressure Which shoes create the most pressure?
F. Pressure b Barometer measures atmospheric pressure b exact height of the Hg depends on atmospheric pressure b usually measured in mm Hg
F. Pressure b Manometer measures contained gas pressure b Difference in height in two arms of U-tube is measure of pressure of gas sample b measured in various different units
F. Pressure b KEY EQUIVALENT UNITS kPa (kilopascal) 1 atm 760 mm Hg 760 torr 14.7 psi
G. STP Standard Temperature & Pressure 0°C 273 K 1 atm kPa -OR- STP
H. Pressure Problem 1 b The average pressure in Denver, Colorado, is atm. Express this in (a) mm Hg and (b) kPa. (a) atm 1 atm 760 mm Hg = 631 mm Hg (b) atm 1 atm kPa = 84.1 kPa
H. Pressure Problem 2 b Convert a pressure of 1.75 atm to kPa and mm Hg. (a) 1.75 atm 1 atm kPa = 177 kPa (b) 1.75 atm 1 atm 760 mm Hg = 1330 mm Hg
H. Pressure Problem 3 b Convert a pressure of 570. torr to atmospheres and kPa. (a) 570 torr 760 torr 1 atm =.750 atm (b) 570 torr 760 torr kPa = 76.0 kPa