1. Kinetic Molecular Theory KMT
THEORY THAT DISCRIBES THE PROPERTIES OF AN
IDEAL GAS

2. Ideal Gases Particles move rapidly in constant random motion Far apart
All collisions perfectly elastic

3. X X IDEAL GASES NEVER Stick together Or interact. Therefore can not be
Solids or liquids X

4. Kinetic Molecular Theory KMT
K: Always in motion or kinetic.
The higher the temperature, the faster the particles move.
M : All matter is made of very tiny molecules. Space between the piece much large than the size of molecules.
T: Elastic collisions: Do NOT interact. No attractions or repulsions between.

6. 4 Variables to describe Pressure Temperature Volume Number / amount P
Atm, torr or
mmHg, Kpa
Celsius or
Kelvin
mL, L, cc, cm3
Molecules or
moles

7. P: Pressure Collisions or Hits
The more collisions, the greater the pressure

8. UNIT FOR PRESSURE Standard Pressure 101.3 kPa = 760 torr,
Atm, torr, mmHg, KPa
Standard Pressure
101.3 kPa = 760 torr,
= 760 mm Hg = 1 atm

9. Pressure Conversions 152 kPa 0.80 kPa How many kPa’s are in 1.50 atm?
1 atm = kPa
1.50 atm x 101.3kPa =
1 atm
How many kPa’s are in 6.0 mm Hg?
6.0 mm Hg x kPa =
760 mm Hg
152 kPa
0.80 kPa

10. Converting from Celsius
00 Celsius = 273 K
K = 0C or 0C = K – 273
Convert 191 K to Celsius
0C = 191 – 273 = -82 0C
Convert 191 C to Kelvin
K = = 464 K

11. Standard Temperature and Pressure
STP
Standard Temperature and Pressure
ST C or 273 K
SP kPa, 760 torr,
760 mm Hg, or 1 atm

12. IDEAL GASES How do we use A, B, C, & D laws to relate Pressure, Temperature, Volume and Amount (n)?

13. Gas Relationships: A, B, C, & D
Relationships between P, V, T, and n
Avogadro’s
Boyle’s
Charles’s
Dalton’s

14. A: Avogadro's Law
Amount (n) is directly proportional to the space occupied (V).
n1 = n V V2

15. n1 = n2 V1 V2 AVOGADRO’S LAW. V2 = 7.0 x 8.8 = 17.6 L 3.5
At room temperature 3.5 moles of gas occupy a volume of 8.8 liters. If the amount is doubled (7.0 moles), what volume is needed to keep the same pressure?
n1 = n V V2
3.5 moles
7.0 moles
8.8 liters
V2 = 7.0 x 8.8
3.5
= 17.6 L

16. BOYLE’S LAW
P1V1=P2V2
Pressure vs Volume

17. C. Charles Law T1 T2 Temperature vs Volume V1 = V2
At a constant pressure, the volume (V) of the gas varies directly with its Kelvin temperature (T).

18. Scuba d5 c9

19. 5.8 atm = 3.3 atm + 0.9 atm + PHe 5.8 - 3.3 - 0.9 = PHe= 1.6 atm
DALTON’S LAW. Solve the following problems. SHOW ALL WORK
A scuba tank contains oxygen, nitrogen and helium gas. If the oxygen pressure is 0.9 atm and the nitrogen pressure is 3.3 atm, what pressure is needed for the helium gas to get a total pressure of 5.8 atm?
5.8 atm = 3.3 atm atm + PHe
= PHe= 1.6 atm

20. PV = nRT Rap

21. PV = nRT Ideal Gas Law R = IDEAL GAS constant 0.08206 (L*atm)/(mol*K)
or 8.31 (L*kPa)/(mol*K)
n = number of moles

22. Mathematical relationship between P ,V, n, and T
IDEAL GAS LAW
Mathematical relationship between P ,V, n, and T
PV = constant value “R” nT

23. Practice Problem
A camping stove uses a propane tank that holds 300. g of C3H8. How larger a tank would be needed to hold the propane as a gas at 250C and a pressure of 3.0 atm?

24. Solution First solve for n 300. g of C3H8. x 1 mole = 6.82 moles
44 grams C3H8
6.82 moles
PV=nRT.
T=250C +273
P= 3.0 atm?
R=0.082 (L*atm)/(mol*K)

25. Solution V = nRT P 56 L T=298 K P= 3.0 atm n=6.82 moles
R=0.082 (L*atm)/(mol*K)
V = 6.82(0.082) 298 L =
3.0 atm
56 L

26. Practice Problem
2.0 moles of N2 is kept in a volume of 0.95 L and a temperature of 30.00C. What is the pressure of the gas under these conditions?

27. Solution P = nRT V 52 atm PV=nRT. n = 2.0 moles T=30. +273 = 303 K
V = .95 L
P= nRT / V
P = nRT V
52 atm
P = 2.0(0.082) 303 atm =
0.95
R=0.082 (L*atm)/(mol*K)

28. PV = nRT Ideal Gas Law R = IDEAL GAS constant 0.08206 (L*atm)/(mol*K)
or 8.31 (L*kPa)/(mol*K)
n = number of moles