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

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

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

4. Endothermic versus Exothermic Example WS ScenarioEndo or Exo? Explain 1Your car burns gasoline as you drive from home to school Exothermic – “burning “ releases energy 2Jerry is baking homemade bread in the oven. Endothermic – “baking” absorbs energy 3The ice melts in your glass of water.Endothermic – “melting” absorbs energy 4Sodium and chlorine combine in an explosive reaction to form table salt. Exothermic – “explosive” shows releasing energy 5Barry Balloon lights his candles to get his hot air balloon to fly. Exothermic – “lighting” candles releases energy 6.Water freezes on the pavement and the roads become icy. Exothermic – “freezing” releases energy

5. Endothermic versus Exothermic Example WS ScenarioEndo or Exo? Explain 7.Mom puts a pot of water on the stove and the water begins to boil Endothermic – “boiling” absorbs energy 8.Water condenses on the side of your glass of cold lemonade. Exothermic - “condensation” releases energy 9.A glass of water left out overnight evaporates. Endothermic – “evaporation” absorbs energy 10.A plant carries out photosynthesis.Endothermic- “photosynthesis” absorbs energy 11.A tree grows.Endothermic – “growing” absorbs energy 12.Sally gets really sweaty as she runs. Then she stops running and the sweat evaporates. (Hint: A 2-part question) Exothermic- “sweat” giving off energy Endothermic – “evaporation” absorbs energy

6. Changes in State

7. Liquid  gas : Vaporization To cause this change…. heat/energy needs to be added system heat surroundings  H vap Heat of vaporization

8. To cause this change…. heat/energy needs to be removed Gas  liquid : Condensation system heat surroundings  H cond Heat of condensation

9. Vaporization Point (the temperature a liquid turns into a gas)= Condensation Point (the temperature a gas turns into a liquid)

10. Melting/Fusion is.. the vibrations in a solid are strong enough to… overcome attractions that keep solid atoms together

11. Solid  liquid: Fusion To cause this change…. heat/energy needs to be added system heat surroundings  H fus Heat of fusion

12. Liquid  Solid: Solidification To cause this change…. heat/energy needs to be removed system heat surroundings  H solid Heat of solidification

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

14. Relationships - +  H vap = -  H cond - +  H fus ­= -  H solid Endothermic Exothermic

15. Energy in Physical Changes

16. Heat of Physical Changes Table On your note sheet: types of thermochem problems Substance Melting point °C Heat of fusion (kJ/kg) Heat of solidification (kJ/kg) Boiling point °C Heat of vaporization (kJ/kg) Heat of condensation (kJ/kg) Helium-269.655.23 -5.23 -268.9320.9 -20.9 Hydrogen-259.3158.6 -58.6 -252.89452 -452 Nitrogen-209.9725.5 -25.5 -195.81201 -201 Oxygen-218.7913.8 -13.8 -182.97213 -213 Ethyl alcohol -114104.2 -104.2 78854 -854 Mercury-3911.8 -11.8 357272 -272 Water0.00334 -334 100.002256 -2256 Sulfur11938.1 -38.1 444.60326 -326 Lead327.324.5 -24.5 1750871 -871 Antimony630.50165 -165 1440561 -561 Silver960.8088.3 -88.3 21932336 -2336 Gold1063.0064.5 -64.5 26601578 -1578 Copper1083134 -134 25675069 -5069

17. When doing word problems…. WANT 1.Find the question word: determine what you are looking for. WANT GIVEN 2.What #s did the problem give you GIVEN 3.If only one # always start grid with that # NEED 4.If Multiple #’s you NEED a formula

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

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

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

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

26. Sublimation SOLID GAS 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…. BUT…. NOT Evaporation is NOT Boiling

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

31. Evaporation It’s a cooling processcooling

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 added Energy/Heat is addedOr EXTERNAL changed the EXTERNAL pressure 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 High Externa l Pressure Creates a High Externa l Pressure   a bubble of vapor can’t form unless  KE=  T   BP is  = hotter liquid= shorter cooking time