1. Ch Gases
I. Physical Properties

2. 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.

3. 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

4. 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

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

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

7. E. Pressure
Which shoes create the most pressure?

8. Standard Temperature & Pressure
F. STP
STP
Standard Temperature & Pressure
0°C K
1 atm kPa
-OR-

9. II. The Gas Laws BOYLES CHARLES GAY-LUSSAC
Ch Gases
II. The Gas Laws BOYLES CHARLES GAY-LUSSAC P V T

10. A. Boyle’s Law P V
PV = k

11. A. Boyle’s Law
The pressure and volume of a gas are inversely related
at constant mass & temp P V
PV = k

12. A. Boyle’s Law
Boyle's Law Video

13. B. Charles’ Law V T

14. B. Charles’ Law
The volume and absolute temperature (K) of a gas are directly related
at constant mass & pressure V T

15. B. Charles’ Law
Charles’ Law

16. C. Gay-Lussac’s Law P T

17. C. Gay-Lussac’s Law
The pressure and absolute temperature (K) of a gas are directly related
at constant mass & volume P T

18. C. Gay-Lussac’s Law
Gay-Lussac’s Law

19. Equations for the three Gas Laws
Charles’s Law
Boyle’s Law
Gay-Lussac’s Law
V1/T1 = V2/T2
P1V1 = P2V2
P1/T1 = P2/T2

20. D. Combined Gas Law
P1V1 T1 =
P2V2 T2

21. V1/T1 = V2/T2 E. Gas Law Problems
A gas occupies 473 L at 36°C. Find its volume at 94°C.
CHARLES’ LAW
GIVEN:
V1 = 473 L
T1 = 36°C = 309K
V2 = ?
T2 = 94°C = 367K T V
WORK:
V1/T1 = V2/T2
(473 L)(367 K)=V2(309 K)
V2 = 562 L

22. P1V1 = P2V2 E. Gas Law Problems
A gas occupies 100. mL at 1.5 atm. Find its volume at 2 atm.
BOYLE’S LAW
GIVEN:
V1 = 100. mL
P1 = 1.5 atm
V2 = ?
P2 = 2 atm P V
WORK:
P1V1 = P2V2
(1.5 atm)(100.mL)=(2 atm)V2
V2 = 75.0 mL

23. E. Gas Law Problems COMBINED GAS LAW P T V V1 = 7.84 mL
A gas occupies 7.84 mL at 0.71 atm & 25°C. Find its volume at STP.
COMBINED GAS LAW
GIVEN:
V1 = 7.84 mL
P1 = 0.71 atm
T1 = 25°C = 298 K
V2 = ?
P2 = 1 atm
T2 = 273 K
P T V
WORK:
P1V1T2 = P2V2T1
(0.71 atm)(7.84 mL)(273 K)
=(1 atm) V2 (298 K)
V2 = 5.09 mL

24. P1/T1 = P2/T2 E. Gas Law Problems
A gas’ pressure is 1 atm at 23°C. At what temperature will the pressure be atm?
GAY-LUSSAC’S LAW
GIVEN:
P1 = 1 atm
T1 = 23°C = 296K
P2 = atm
T2 = ? P T
WORK:
P1/T1 = P2/T2
(1atm)T2 = (0.737 atm)(296K)
T2 = 218 K = -55°C

25. Ch Gases
III. Ideal Gas Law

26. A. Avogadro’s Principle

27. A. Avogadro’s Principle
Equal volumes of gases contain equal numbers of moles
at constant temp & pressure
true for any gas V n

28. UNIVERSAL GAS CONSTANT
B. Ideal Gas Law PV nT V n PV T
= k
= R
UNIVERSAL GAS CONSTANT
R= Latm/molK
R=8.315 dm3kPa/molK

29. UNIVERSAL GAS CONSTANT
B. Ideal Gas Law
PV=nRT
UNIVERSAL GAS CONSTANT
R= Latm/molK
R=8.315 dm3kPa/molK

30. B. Ideal Gas Law IDEAL GAS LAW P = ? atm n = 0.412 mol
Calculate the pressure in atmospheres of mol of He at 16°C & occupying 3.25 L.
IDEAL GAS LAW
GIVEN:
P = ? atm
n = mol
T = 16°C = 289 K
V = 3.25 L
R = Latm/molK
WORK:
PV = nRT
P(3.25)=(0.412)(0.0821)(289)
L mol Latm/molK K
P = 3.01 atm

31. B. Ideal Gas Law IDEAL GAS LAW V = ? n = T = 25°C = 298 K P = 1 atm
Find the volume of 2.7 mol of O2 at 25°C and 1 atm.
IDEAL GAS LAW
GIVEN:
V = ?
n =
T = 25°C = 298 K
P = 1 atm
R = Latm/molK
WORK:
85 g 1 mol = 2.7 mol
32.00 g
2.7 mol
PV = nRT
(1)V=(2.7mol) (8.315) (298)
V = 64 L