1. Gas Laws
Chapter 5

2. Units of Pressure Kilopascals (SI unit)
Millimeters of mercury is the same as a torricelli
Atmospheres
Pounds per square inch
101.3 kPa = 760 mm Hg (torr) = 1 atm = 14.7 psi

3. Barometers

4. Open Manometers

5. Closed Manometer

6. Manometer problems

7. Answers:
mm Hg
mm Hg
mm Hg

8. Manometer Problems continued

9. STP Standard Temperature and Pressure
Standard Temperature is 0 ˚C or 273 K
Standard Pressure is kPa
Kelvin = ˚Celcius + 273

10. Boyle’s Law
If the temperature remains constant, Pressure and Volume have an inverse relationship
P1 x V1 = P2 x V2
Watch for unit agreement!

11. Charles’ Law
If pressure remains constant, then volume and Kelvin temperature will have a direct relationship.
V1 = V2
T T2
Temperature MUST be in Kelvin…volume needs unit agreement

12. Gay-Lussac’s Law
If the volume of a gas is held constant, then there is a direct relationship between pressure and Kelvin temperature.
P1 = P2
T T2
Temperature MUST be in Kelvin and unit agreement for pressure

13. Combined Gas Law
P1V1 = P2V2 T1 T2 Make sure you have unit agreement and temperature must be in Kelvin!

14. PV= nRT Ideal Gas Law P= Pressure V = Volume (in Liters) n = moles
R = Gas Constant (8.314 L·kPa/mol·K)
T = Temperature in Kelvin

15. Avogadro’s Law
V1 = V2
n n2
V = volume
n= moles

16. Dalton’s Law of Partial Pressures
For a mixture of gases in a container, the total pressure exerted is the sum of the pressures that each gas would exert if it were alone.
Ptotal = P1 + P2 + P3 + …

17. Kinetic Molecular Theory
The particles are so small compared to the distances between them that the volume of the individual particles can be assumed to be negligible (zero).
The particles are in constant random motion. The collisions of the particles with the walls of the container are the cause of the pressure exerted by the gas.
The particles are assumed to exert no forces on each other; they are assumed to neither attract nor repel each other.
The average Kinetic energy of a collection of gas particles is assumed to be directly proportional to the Kelvin temperature of the gas.

18. Real Gases Have finite volumes Do exert forces on each other
Van der Waals equations correct for this reality
Gases only behave ideally at:
High Temperatures and Low Pressures

19. Meaning of Temperature
Kelvin Temperature indicates the average Kinetic energy of the gas particles.
(KE) avg = 3/2 RT

20. Root Mean Square Velocity
Average Velocity of the gas particles
U rms = √3RT/M

21. Effusion Effusion is diffusion of a gas through a small opening
Rate of Effusion of Gas 1 = urms for gas 1
Rate of Effusion of Gas 2 urms for gas 2