1. Behavior of Gases
Gas Laws

2. Gas Variables Temperature (T) = avg Kinetic Energy
Kelvin = C + 273
Always use Kelvin (K)
Volume (V) = length x width x height
Pressure (P) = force/Volume
Amount of Matter (n) = number of moles

3. Kinetic Theory of Matter
All Matter is made of tiny particles (Atoms or Molecules)
The Particles are in constant Motion
The Particles undergo elastic collisions
No Energy is gained or lost

4. Ideal Gas Particles have no volume Particles are in:
Constant, rapid, random motion
Always move in straight lines
No attractive or repulsive forces
Temperature (K) proportional to Kinetic Energy

5. Standard Temp and Press (STP)
273 K and 1 atm
273 K and kPa
273 K and 760 mm Hg (or torr)

6. Gas Laws Boyle’s Law Charles’ Law Gay-Lussac Law Avagadros Law
Dalton’s Law
Combined Law
Ideal Law
PiVi = PfVf
Vi/Ti = Vf/Tf
Pi/Ti = Pf/Tf
Vi/ni = Vf/nf
Pt = P1 + P2 + ….
niTi nfTf
PV = nRT

7. Pressure Versus Volume P1V1 = P2V2
Pressure Increases-Volume Decreases
Pressure Decreases-Volume Increases

8. Pressure and Volume
As a general rule, as Pressure goes up, Volume must go down.
If the same amount of material (moles) are placed in two different containers, the smaller container will have a greater pressure.

9. Volume Versus Temperature V1/T1 = V2/T2
Volume Increases-Temperature Increases
Volume Decreases-Temperature Decreases
Temp in Kelvin

10. Pressure Vs Temperature P1/T1 = P2/T2
Pressure Increases-Temperature Increases
Pressure Decreases-Temperature Decreases
Temp in Kelvin
Kelvin = C + 273

11. Avogadro’s Principle
Equal volumes of gases under the same conditions have:
Equal number of moles

12. Avagadro’s Law
As the VOLUME of a container increases, the amount of MATTER (moles) must increase proportionally, If Pressure and Temperature are constant
As the PRESSURE of a container increases, the amount of MATTER (moles) must increase proportionally, If Volume and Temperature are constant

13. Pressure versus Material
If different amounts of material are placed in the same size containers, at the same temperature, the more material the greater the pressure.

14. What is the Paradox? In looking at these Gas Laws a Paradox emerges:
As Pressure goes UP, Volume Goes DOWN
As Volume goes DOWN, Temperature goes DOWN
As Temperature goes DOWN, Pressure goes DOWN
How is that possible? Pressure went UP to start with?

15. Combined Gas Law P1V1/n1T1 = P2V2/n2T2
Real World: You change one variable - ALL Change
Temp must be in Kelvin

16. Partial Pressures Pt = P1 + P2 + …..
Total Pressure = Adding up the Parts
Dalton’s Law

17. Ideal Gas Law PV = nRT P = Pressure V = Volume n = Number of Moles
T = Temperature (K)
R = Universal Gas Constant
If P in atm, then R =
If P in kPa, then R = 8.314
If P in mmHg, then R = 62.4

18. Boyle’s Law Example
The volume of the lungs is measured by the volume of air inhaled or exhaled.  If the volume of the lungs is L during exhalation and the pressure is KPa, and the pressure during inhalation is KPa, what is the volume of the lungs during inhalation? 

19. Charles Law Example
A gas system has initial volume and temperature of 3390mL and 159oC If the volume changes to 6.79L, what will the resultant temperature be in oC?

20. Gay-Lassac Example
Determine the pressure change when a constant volume of gas at 1.00 atm is heated from 20.0 °C to 30.0 °C.

21. Avagadro’s Law Example
If a 500 mL glass beaker were determined to contain 0.25 moles of He gas, at STP, how many moles of the He gas would have to be in a 1500 mL glass beaker?

22. Combined Gas Law
A closed gas system initially has pressure and temperature of 1.57atm and 568K with the volume unknown. If the same closed system has values of 2.00 atm, 6240mL and 1165 oC, what was the initial volume in mL?

23. Dalton’s Law Example
A 1.5 Liter container of gas was determined to consist of Nitrogen Gas, Oxygen Gas and Carbon Dioxide Gas. The pressure of Nitrogen gas was determined to be 95.0 kPa, and Oxygen gas was determined to be 32.0 kPa, if the Total Pressure was kPa, what is the Pressure of Carbon Dioxide?

24. Ideal Gas Law
How many moles of an ideal gas are in a volume of 5530mL with a temperature of 34C and a pressure of 1.41atm ?

25. The Gas Laws

26. Phase Diagrams
A Diagram that predicts the Phase

27. Terms for Phase Diagrams
Solid Phase – Normally at Low Temps and High Pressure
Liquid Phase – Normally at either Low Temps or High Pressure
Gas Phase – Normally at High Temps and Low Pressure
Triple Point – A highly precise point in which a substance exists in all three phases
Critical Point – The Point at which the compound falls apart.

28. Carbon Dioxide Phase diagram

29. Water Phase Diagram