1. GASES

2. Aim 1: To review properties of the states of matter and to assign them levels of entropy.

3. Entropy Entropy = disorder, randomness
Nature loves to increase entropy!
… increases when…
- temperature increases
-something dissolves
(becomes aqueous)
- highest in gases

4. States of Matter--Solids
Particle arrangement: Close, ordered, vibrate in place
Intermolecular forces of attraction: strong, high forces are hard to separate
Shape: definite
Volume: definite
Entropy: low

5. Liquids Particle arrangement: less ordered, flow around each other
Intermolecualar forces of attraction: medium
Shape: takes the shape of the container
Volume: definite
Entropy: medium, can be increased by dissolving matter into the liquid

6. Gases Particle arrangement: Far apart, random movement
Intermolecular forces of attraction: low, molecules are not close together to feel an attraction
Shape: takes the shape of the container
Volume: Uniformly fills the container, COMPRESSIBLE**
Entropy: high

7. More on Solids—Two Categories
Amorphous solids are “solids without form” AKA Glass

8. Crystalline solids have the crystal lattice structure and are considered “true” solids

9. More on Liquids– Two Properties
Volatile Liquids are those that easily evaporate and therefore have weak intermolecular forces

11. Liquids
Viscous liquids: liquids that resist motion whenever they move past each other– Think molasses
Stronger attractive forces= higher viscosity
Increasing temperature causes molecules to move faster so they have less resistance!

12. STP Standard Temperature and Pressure TABLE A 273K =_________DC
1 atm and 101.3kPa

13. Aim 2: To predict the behavior of gases according to their properties.

14. Gases Gases can be elements, compounds, or mixtures
All gases behave in similar ways.
Not all gases are colorless.

15. Gases
Gases collide into the walls of the container which exerts pressure.
Gases have low density and mass.

16. Volume The volume of a gas is equal to its container.
Usually measured in L or mL

17. Temperature KELVIN ONLY!!!!!! K=C+273 this is on table T
Standard temperature=273K

18. 78DC= _____________K
900 K=________________DC
Which is colder, 65 DC or 354 K?

19. Pressure
Gas particles exert pressure by colliding into the walls of the container. More collisions=higher pressure
Standard pressure= 1atm=101.3kPa

20. Aim 3: To predict the behavior of gases using different gas laws.

21. Boyle’s Law P1V1=P2V2 ONLY compares P and V
Amount of gas and T remain constant
States: volume and pressure are inversely related.

23. Boyle
As P___________ V_____________ and as P____________ V _____________

24. What happens to the volume that the gas occupies when the piston is pushed down?
What happens to the volume that the gas occupies when the piston is raised?

25. When volume is increased, particles will have decreased collisions with the container walls, and therefore pressure will decrease. When volume is decreased, particles will have increased collisions with the container walls, and therefore pressure will increase.

26. Animation
1. A sample of gas has a volume of 34.2 L when its pressure is 1.49 atm. What volume will the gas occupy at 2.7 atm if temperature remains constant?

27. 2. If 50. 0L of hydrogen gas is exerting a pressure of 105
2. If 50.0L of hydrogen gas is exerting a pressure of kPa has its volume expanded to 75.0 mL, what would the new pressure of the hydrogen gas be?

28. Charles’ Law (V1 = V2) T1 T2 Compares V and T
Amount of gas and Pressure remain unchanged
States: volume and temperature of a gas are directly related.

30. As T __________V __________

31. If temperature is increased, particles will move more rapidly
If temperature is increased, particles will move more rapidly. Volume will increase so the number of collisions with the container wall will increase

32. Charles’
Animation

33. Practice
1. A sample of gas occupies 500. mL at 313K and 1atm. What volume will this gas occupy at STP? 2. Calculate the final volume when a mL sample of neon gas at 288K is cooled to standard temperature and pressure is constant.

34. Guy-Lussac’s (P1 = P2) T1­ T2
Compares P and T
Amount of gas and Volume remain constant
States: the pressure of a fixed mass of gas varies directly with Kelvin temperature
As T__________P___________

36. If temperature is increased, particles will move more rapidly
If temperature is increased, particles will move more rapidly. This leads to increased number of collisions with the container which means the pressure increases.

37. Practice
1. A gas exerts 200.0kPa at 323K. At what temperature will the pressure be kPa? 2. If neon gas exerts a pressure of 1.25 atm at 301 Kwhat would the temperature be if the pressure is changed to 725 mmHg?

38. P T V