1. I. Physical Properties (p. 403 - 412)
Ch. 12 & 13 – Gases
I. Physical Properties (p )

2. A. Kinetic Molecular Theory
The kinetic molecular theory describes the behavior of matter in terms of particles in motion.
Objects in motion have energy called kinetic energy

3. A. Kinetic Molecular Theory
Particles in an ideal gas…
have no 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

4. B. Real Gases 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

5. C. 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
C. Johannesson

6. C. Characteristics of Gases
Gases can be compressed.
no volume = lots of empty space
Gases undergo diffusion & effusion.
random motion

7. D. Describing Gases Gases can be described by their: Temperature K
Pressure
Volume
Number of molecules/moles K
atm L #

8. E. Temperature
Always use absolute temperature (Kelvin) when working with gases. ºF ºC K
-459 32
212
-273
100
273
373
K = ºC + 273
C. Johannesson

9. Which shoes create the most pressure?
F. Pressure
Which shoes create the most pressure?
Why?

10. F. Pressure exact height of the Hg depends on atmospheric pressure
Barometer
measures atmospheric pressure = result of mass of air pulled toward Earth by force of gravity
exact height of the Hg depends on atmospheric pressure
usually measured in mm Hg

11. F. Pressure Manometer measures contained gas pressure
Difference in height in two arms of U-tube is measure of pressure of gas sample
measured in various different units

12. Measuring Pressure
Vacuum
Gas Pressure

13. Measuring Pressure
Vacuum
Gas Pressure

14. Measuring Pressure
Vacuum
Gas Pressure
Manometer

15. F. Pressure KEY EQUIVALENT UNITS 101.325 kPa (kilopascal) 1 atm
760 mm Hg
760 torr
14.7 psi

16. Standard Temperature & Pressure
G. STP
STP
Standard Temperature & Pressure
0°C K
1 atm kPa
-OR-

17. H. Pressure Problem 1
The average pressure in Denver, Colorado, is atm. Express this in (a) mm Hg and (b) kPa.
760 mm Hg
(a) atm
= 631 mm Hg
1 atm
kPa
(b) atm
= 84.1 kPa
1 atm

18. H. Pressure Problem 2 Convert a pressure of 1.75 atm to kPa and mm Hg.
(a) 1.75 atm
= 177 kPa
1 atm
760 mm Hg
(b) 1.75 atm
= 1330 mm Hg
1 atm

19. H. Pressure Problem 3
Convert a pressure of 570. torr to atmospheres and kPa.
1 atm
(a) 570 torr
= .750 atm
760 torr
kPa
(b) 570 torr
= 76.0 kPa
760 torr