1. Changes in the state of matter
Phase Changes

2. State of matter change triangle

3. Change in a material’s states of matter
Is a Physical, not Chemical change
No Chemical reaction occurs
Done by adding or subtracting energy to the amount held by each atom
Also called a phase change

4. When state of matter changes
What does not change:
The composition of the matter
The mass
(same mass of liquid water as steam)

5. When state of matter changes
What does change:
The volume of the matter
The amount of energy held within the matter

6. Phase change Categories

7. Endothermic change Occurs when object gains energy from other sources
Added energy result in less restrictive connections between atoms, molecules
Types of endothermic change
Melting
Evaporation or boiling
Sublimation

8. Exothermic change
Occurs when an object loses energy to other objects or the environment
Results in more restrictive connections between atoms
Types of exothermic change:
Freezing
Condensation
Deposition (sublimation)

9. Energy transfers associated with water
Energy released to solidify into ice
Energy absorbed to liquefy into water
Energy released to condense into liquid
Energy absorbed to vaporize into a gas

10. Making Smores
Which material involved with making a smore undergoes a phase change?
Endo or Exo changes?

11. Fire
Heat from an outside source must be applied to the combustable material to make it burn (endothermic action)
The products(hot air, ash) released from the chemical reaction have an increased amount of heat (endo)
These products lose their heat as the move away from the source of the reaction (exothermic)
The surrounding environment (air, the ring of rocks that border the fire, the marshmallow, you) become hotter as energy is transferred to you from the products of the fire

12. More examples of Exothermic Changes

13. Condensation Convert from gas to liquid
Dew, the ‘sweating’ of cold bottles on hot summer days

14. Condensation: molecules have to slow down

15. condensation
Look at the glasses
During the summer

16. Exothermic Change of State

17. Can you think of any other examples of condensation?

18. Freezing Convert from liquid to solid Making ice cubes
The cooling of molten lava to rock

19. Solidification

20. Freezing?
What will freeze in this picture in time?

21. Deposition (sometimes called sublimation as well)
Gas to solid without turning into a liquid
Frost on the ground

22. Frost on ground

23. Where else does freezing occur

24. More examples of Endothermic Change

25. Evaporation, Boiling Convert from liquid to gas
The drying up of lakes and ponds during the summer
Boiling water in a pan

26. Evaporation of water at the salt flats: energy is transferred to the water molecules from the sun

27. melting Convert from solid to liquid Making Iron or Titanium
a chocolate bar left out on blacktop

28. Melting
What loses energy?
What gains energy?

29. Melting of Titanium into ingots

30. Where is the energy coming from to melt or sublimate the ice?

31. Sublimation Direct change from solid to a gas Other examples:
Freeze-dried food (coffee)
Ice Cubes getting smaller in freezer
Freezer-burn (too long, improperly wrapped)

32. Sublimation Dry Ice – solid carbon Dioxide

33. Sweating

34. Which phase changes are connected with sweating?

35. As you sweat, energy is transferred from your body to the water/oil droplets

36. Sweating Exercising increases the energy in your body
Some of that energy is transferred to the molecules of water and oil that make up your sweat.
Those water/oil molecule move through pores, evaporate when no longer confined inside the body, taking heat with them
The transfer of that heat helps your body cool off

37. Example Sweating: You lose energy (exothermic)
Sweat gains energy (endothermic)
Energy has been transferred, not created or destroyed
You feel cooler
Sweat goes from liquid to gas (boiling, evaporation)

38. Temperature and phase change
When substance gains or loses energy, either its temperature or its phase will change, but not both at the same time
When adding heat to ice, temp will not rise until all ice has melted

39. Conservation of mass and energy
In a closed environment:
Mass can not be created or destroyed
Energy can not be created or destroyed
If some atom/molecule gains energy in some form, another must lose energy in some form

40. Conservation of a system
The amount of mass or energy in a closed system remains constant, but can be rearranged or transformed

41. Closed System
A closed system is a collection of objects that can transfer energy, mass only between themselves
There is no gain or loss of energy, mass from a closed system

42. Extras

43. Refrigerators
The refrigerant in the coils at the back of the refrigerator take out energy from air inside the refrigerator Refrigerant evaporates inside coils
Gas flows to outside of refrigerator, releases heat to environment, refrigerant condenses

45. Air Conditioners, Heaters

46. Air Conditioner Hot, humid air is sucked in from the room
Heat is extracted from air and transferred to water in piping
The cool dry air is recycled back into room
Water condenses inside the air conditioner
A fan takes the heat from the water and blows it away from unit outside of home