1. Ideal gases: Gas particles do not attract one another Gas particles do not occupy volume There are no ideal gases in real life

2. Real Gases: Do attract one another Do have volume

3. Question: Which gases are almost “ideal”? ANSWER: ones that are non polar (van der waals forces, so little attraction for each other) And ones that are smallest molecules (little volume)

4. Almost ideal gases: Which gas is closer to being ideal, hydrogen gas or water vapor? H 2 H 2 O

5. Almost ideal gases: Which gas is closer to being ideal, hydrogen gas or water vapor? H 2 H 2 O small BIG

6. Almost ideal gases: Which gas is closer to being ideal, hydrogen gas or water vapor? H 2 H 2 O small BIG Non polar Polar

7. What are the best conditions for gases to behave as much like ideal gases as possible? ANSWER: When the attraction between molecules is the least When the volume of the particles is smallest as compared to the size of the container

8. When is the attraction between molecules the least? When they are moving fast When they are far apart Moving fast = high average kinetic energy = high temperature Far apart = big volume, = low pressure

9. So gases behave most like ideal gases under conditions of: High Temperature (least attraction) Low pressure (fraction of the particle volume as compared to the total volume of is smallest)

10. So gases behave LEAST like ideal gases under conditions of: LOW Temperature (slow moving) HIGH pressure (close together in small container)

11. Which is most ideal gas? NH 3 or He: explain why

12. Which is most ideal gas? Water vapor at 300K and.5 atm or Water vapor at 100 K and 9 atm Explain why!

13. Avogadro’s Hypothesis: One mole of ANY gas Contains 6.02 x 10 23 gas molecules ALWAYS has a volume of 22.4 LITERS at STP

14. Each container has one mole of a gas The masses are different (GFM’s are different) The volumes are the same (22.4 L) The number of molecules in each is the same (6.02 x 10 23 )