1. Gases
Hydrogen and Oxygen – Renewable Resource

2. Kinetic-Molecular Theory
All particles are in constant motion.
Explains properties
of matter.

3. Ideal Gas = follows K-M theory
5 Assumptions
Lots of tiny particles that are far apart
Elastic collisions = no loss of energy
Have kinetic energy (KE) – constant motion
No forces of attr. or rep. between particles
Avg. KE depends on temp.

4. KE = ½ mv2 Speed changes with temp.
Gases at the same temp have the same KE – lighter particles (H2) have higher speeds than heavier particles (O2)

5. Expansion No definite shape or volume Expand to fit any ‘container’
Making fire with steam (2 min)

6. Fluidity Density Gas particles easily flow past each other. Very low
Particles are very far apart.

7. Compressibility
Particles pushed together
Decreases volume

8. Diffusion Effusion Mixing of particles caused by random motion
Gas particles pass through tiny openings

9. Real Gases Do not behave according to K-M theory Real Gases
Occupy space
Exert forces on each other

10. Pressure (P) Force per unit area Mount Everest Hawaii Beach
Badlands in Death Valley
Cloud in a bottle Vacuum Pack (3 min)

11. Measuring Pressure Barometer Manometer Measures atmospheric pressure
Height of mercury depends on atmospheric pressure
Manometer
Measures pressure of enclosed gas

12. Barometer

13. Common Barometer

14. Manometer

15. Units of Pressure Millimeters of Mercury (mm of Hg) Atmospheres (atm)
kiloPascals (kPa)

16. Converting Units of P 760 mm Hg (torr) = 1 atm = 101.325 kPa
At sea level, P = 760 mm Hg
Ultimate Can Crusher (2 min)

17. Temperature Measure of the energy of the particles
Units of Temperature
Degrees Celsius (C)
Kelvin (K)
ºCelsius = Kelvin
Use a thermometer
Fire Tornado (1 min), Fire Tornado,
Double Tornado (water)
Fire Tornado explanation (1.5 min)
Lord Kelvin

19. STP
1 atm and 0C (273 K)

20. Boyle’s Law V varies inversely with P (constant T) PV = k P1V1 = P2V2
Peeps (2 min)

21. Charles’s Law V varies directly with Kelvin T V1 = V2 T1 T2
V = k’T
V1 = V2
T T2
Absolute Zero = 0K or –273C

23. Gay-Lussac’s Law
P varies directly
with Kelvin T
P = k”T
P1 = P2
T1 T2

24. Units must correspond to cancel!!
Combining Boyle’s, Charles’ and Gay-Lussac’s laws produces the Combined Gas Law
P1V1 = P2V2
T T2
Units must correspond to cancel!!
Review Gas Laws Tornado
Hot air balloon

25. Mount Everest Video 7 minutes

26. Scuba Diving Video 9 minutes

27. Dalton’s Law of Partial Pressure
Total Pressure, PT, of a mixture of gases equals the sum of the partial pressures of each component gas
PT = P1 + P2 + P3 + etc… where P1, P2, P3, etc. are the partial pressures of each component gas.
P1 = X1PT etc. where X1 is the mole fraction of gas 1 in the mixture.

28. Gases collected by water displacement
Patm(total) = Pgas + PH2O(g)
Read from a barometer
Found on a table – must be given

29. Gay-Lussac’s Law of Combining Gases
At constant T and P, the volumes of gaseous reactants and products can be expressed as ratios of small whole numbers
EX: 2 H O2  2 H2O
2 Liters of hydrogen react with 1 L of oxygen to make 2 liters of water

30. Avogadro’s Law
Equal volumes of gases at the same T and P contain equal numbers of molecules
EX: 2 H O2  2 H2O
2 molecules of hydrogen and 1 molecule of oxygen combine to form 2 molecules

31. Ideal Gas Law
Volume
Constant
PV = nRT
Moles
Temperature
Pressure

32. R – The constant R = 62.4 mm Hg  L molK R = 0.0821 atm  L
R = kPa  L

33. The Ideal Gas Law can also be related to the Molar Mass of a gas
The Ideal Gas Law can also be related to the Molar Mass of a gas. Since n = m/Mm substituting in for n yields PVMm = mRT and rearranging produces -
Mass
Molar Mass
Mm = mRT PV

34. The Ideal Gas Law can also be used to determine the density of a gas
The Ideal Gas Law can also be used to determine the density of a gas. Substituting d = m/V into the previous equation Mm = mRT VP we have
PMm = dRT
Rearranging yields: d = PMm RT