1. Gas Laws

2. Part 1: Kinetic Theory (most of this should be review)

3. Kinetic Theory of Matter  All matter is moving.  Kinetic Energy is the energy of motion.  Temperature is a measure of Kinetic Energy.  Higher temperature indicates more motion.  Motion stops at 0 K (-273˚C)

4. Kinetics of Phases  Solids the particles have strong Inter- molecular forces (IMF) with each other but vibrate in place.  Liquids have some IMF but can change position relative to each other.  Gases have very low IMF and have very little interaction with one another.

5. So...  Solids have a definite shape and volume.  Liquids have definite volume but not definite shape (take the shape of their container)  Gases have no definite shape or volume (expand to fill size and shape of container).

7. Temperature  Measure of the average kinetic energy.  Some particles can be moving very fast.  Some will move very slowly.  Most are average.

8. Vapor Liquid Equilibrium  Stoppered flask, particles cannot escape.  Open beaker they can – eventually will evaporate.

9. Part II: Properties of Gases

10. Air Pressure is Due to Gravity  Remember STP?  Standard Air Pressure is measured at Sea Level: 101.3KPa

11. Compressibility  Gas molecules are very small  The spaces between them are very large  The molecules can be forced closer together  They can absorb a lot of energy  E.g. car air bags

12. Intermolecular Forces  The molecules are randomly moving very fast  They move in straight-line paths  Only change direction when they bump into something  The molecules are SO far apart that the IMF are considered to be zero

14. Variables in the Gas Formulas  P = pressure in kilopascals (kPa)  V = volume of the gas in litres (L)  T = temperature in kelvins (K)  n = number of moles

15. Δ Moles, Δ Pressure  Volume remains constant  Temperature remains constant  Doubling the number of gas particles (moles) doubles the pressure

16. Δ Volume, Δ Pressure  Temperature remains constant  Number of particles (moles) remains constant  Decreasing the volume by half will double the pressure

17. Δ Temperature, Δ Pressure  Volume remains constant.  Number of moles remains constant  Doubling the temperature will double the pressure

18. Part III: Gas Laws

19. Boyle’s Law  Temperature remains constant  Pressure goes up, volume goes down  Pressure goes down volume goes up

20. Inverse relationship creates a curve, not a line…

21. Charles’s Law  Pressure is constant  Temperature goes up, volume goes up  Temperature goes down, volume goes down.

22. The Mylar Balloon on a cold day…  Demo

23. Gay-Lussac’s Law  Volume is constant  Temperature increases, pressure increases  Temperature decreases, pressure decreases.

24. Ideal Gas Law  PV=nRT where R is the gas law constant 8.31 L kPa Ideal Gases  Follow the law precisely  The particles must have no volume  Must have no IMF  No ideal gases exist

25. Guess where we find this…

26. The most ideal gases are H 2 and He