To cause the state of matter to change….

1. To cause the state of matter to change…. Heat/Energy needs to be….. added or removed

2. Heat that is removed is…. Exothermic surroundings system heat

3. Heat that is added is…. Endothermic surroundings system heat

4. Endothermic versus Exothermic Example WS

5. Endothermic versus Exothermic Example WS

6. Changes in State

7. Liquid  gas : Vaporization To cause this change…. heat/energyneeds to be added Hvap surroundings system Heat of vaporization heat

8. Gas  liquid : Condensation To cause this change…. heat/energyneeds to be removed Hcond surroundings system heat Heat of condensation

9. VaporizationPoint (the temperature a liquid turns into a gas) = CondensationPoint (the temperature a gas turns into a liquid)

10. Melting/Fusionis.. thevibrations in a solid are strong enough to… overcome attractions that keep solid atoms together

11. Solid  liquid: Fusion To cause this change…. heat/energyneeds to be added Hfus surroundings system Heat of fusion heat

12. Liquid  Solid: Solidification To cause this change…. heat/energyneeds to be removed Hsolid surroundings system heat Heat of solidification

13. Melting (Fusion)Point (the temperature a solid turns into a liquid) = SolidificationPoint (the temperature a liquidturns into a solid)

14. Relationships Endothermic Exothermic +Hvap = - Hcond +Hfus­= -Hsolid

15. Energy in Physical Changes

16. Heat of Physical Changes TableOn your note sheet: types of thermochem problems

17. When doing word problems…. • Find the question word: determine what you are looking for. WANT • What #s did the problem give you GIVEN • If only one # always start grid with that # • If Multiple #’s you NEED a formula

18. Ex.1 How much heat is absorbed when 24.8 g water is evaporated?

20. Ex 2How much heat is transferred when 400 grams of mercury (Hg) is vaporized?

22. Ex 3If 300 kJ of heat is available, how much copper can be melted?

24. Ex 4How much heat is transferred when 100 grams of ethyl alcohol condenses?

26. Sublimation SOLID skips liquid stage goes straight into GAS stage

27. Demo 1: Sublimation

28. You forgot your glass of water outside. The next time you are outside, you realize your glass is empty. What happened?

29. Evaporation Vs Boiling • Both are Vaporization • Both allow liquid turn into a gas BUT…. • Evaporation isNOTBoiling

30. Evaporation In an open container Δ occurs @ the surface

31. Evaporation It’s a cooling process

32. Evaporation Explain how the following description is an analogy for evaporative cooling: If the fastest runner is removed from a race, the resulting average speed of the runners that remain will be lower.

33. Boiling Liquid has enough HEAT/ENERGY to overcome the External Pressure Vapor Pressure = External Pressure

34. to make something boil Energy/Heat is added Or the EXTERNALpressure is changed

35. Boiling

36. Affect of  Temp on Contained Liquid  KE of particles  particle collisions  VP This why a tea kettle whistles

37. Vacuum no gas particles = no collisions = NO PRESSURE

38. Demo 2: Boiling

39. Atmospheric Pressure Gas particles in Air colliding in earth’s atmosphere

40. More gas particles = More collisions= More pressure

41. Elevation and Atmospheric Pressure ↑ Elevation = ↓ Atmospheric Pressure b/c less gas particles =less collisions =  P Sea Level more gas particles = more P

42. Elevation and BP

43. Pressure Cooker Creates a HighExternal Pressure abubble of vapor can’t form unless KE= T  BP is = hotter liquid= shorter cooking time