1. Chapter 13 States of Matter

2. Kinetic Energy = Energy of motion
Kinetic Theory = all matter consists of particles in constant motion

3. Average Kinetic Energy
at any given temperature the particles of all substances have the same average kinetic energy
No kinetic energy = no movement = absolute zero
Absolute zero = oC or 0 K (Kelvin)

4. Temperature vs. Heat

5. Let’s Learn: How heat spreads from one region to another. Examples:
How the whole copper rod get hot when we heat one end
How does the heat spread throughout the whole pot of water when we are only heating the bottom
How does the heat from the Sun reaches us

6. What Happens??? All things are made up of particles
When things get heated, they absorb heat energy.
This means that the particles are absorbing the heat energy With more energy, the particles are able to move faster
When the particles move faster, the temperature of the object increases.
Temperature increase means the object gets hotter.

7. Three Processes of Heat Transfer
Conduction
Convection
Radiation

8. CONDUCTION Occurs mainly in solids Two types of conduction
Molecular vibration
Free electron diffusion
Note: Conduction is not the main form of heat transfer in liquids and gases because their molecules are spaced further apart.

9. Molecular Vibration
When heat is supplied to one end, the molecules at the hot end start to vibrate more vigorously.
In the process, they ‘bump’ into their neighboring molecules. In doing so, some energy is transferred to the neighbor.
The neighbor molecule gains energy and starts to vibrate more vigorously. The cycle continues.

10. Conduction Animation http://www.scienceonline.co.uk/flash/solid.html

11. Free Electron Diffusion
This form of conduction takes place only in metals. As only metals have free electrons.
The electrons are freed from the molecule when heated and they travel towards the cold end.
At the cold end they collide into a molecule therefore passing all their energy to the molecule.

12. Comparing the 2 Mechanisms
Molecular vibration
Free electron diffusion
Occurs in all solids
Slow process
Occurs in metals only
Fast process
This explains why metals heat up faster:
Metals have 2 mechanisms of conduction occuring at the same time.
In metals, free electron diffusion is the main mechanism, which is faster.

13. Conductors and Insulators
Materials that can conduct heat easily and readily (eg. Metals) are known as conductors.
Materials that do not conduct heat easily (eg. Water, air, plastic) are known as insulators.

14. Convection Occurs in liquids and gases
Does not occur in solids because the molecules are not free to move around

15. What happens during convection?
Taking the example of heating water
Water at the bottom is heated first
Heated water expands
When water expands density decreases
Heated water of lower density starts to rise
Cooler water of higher density rushes in from sides to take its place
The cooler water gets heated and the cycle repeats.
Convection currents are set up.

16. Radiation
Radiation does not require a medium to transfer heat. (can occur in a vacuum)
Sun releases electromagnetic waves (heat is contained in the waves as infra-red)
Hotter objects radiates more heat.

17. States of Matter (characteristic properties)

18. What state of matter does this particle motion exhibit?

19. retains a fixed volume and shape
SOLID!
solid
retains a fixed volume and shape
not easily compressed
does not flow easily

20. What state of matter does this particle motion exhibit?

21. assumes the shape of the part of the container retains its volume
LIQUID!
liquid
assumes the shape of the part of the container retains its volume
not easily compressed
flows easily

22. What state of matter does this particle motion exhibit?

23. assumes the shape and volume of its container
GAS!
gas
assumes the shape and volume of its container
easily compressed
flows easily

24. Characteristics of Solids, Liquids and Gases
Cool
Cool
Characteristics of Solids, Liquids and Gases
gas
liquid
solid
takes the shape and volume of its container
Volume remains the same, takes shape of container
Keeps its shape and volume
easily compressed
not easily compressed
not easily compressed
flows easily
flows easily
does not flow easily

25. States of Matter (molecular level comparison)
Particles = atoms, molecules, or ions

26. What state of matter does this particle motion exhibit?

27. SOLID! little free space between particles solid Ordered arrangement
rigid - particles locked into place/fixed
little free space between particles

28. What state of matter does this particle motion exhibit?

29. LIQUID! liquid disorder particles can move/slide past one another
little free space between particles

30. What state of matter does this particle motion exhibit?

31. GAS! gas total disorder motion: constant, rapid, random
lots of free space between particles
Collisions are elastic – total kinetic energy remains constant

32. Molecular Level Comparison of Solids, Liquids and Gases
Cool
Cool
Molecular Level Comparison of Solids, Liquids and Gases
solid
liquid
gas
Ordered arrangement
disorder
total disorder
motion: constant, rapid, random
rigid - particles locked into place/fixed
particles can move/slide past one another
lots of free space between particles
little free space between particles
little free space between particles
Collisions are elastic – total kinetic energy remains constant

33. Changes in State

34. Evaporation
Vaporization = the conversion of a liquid to a gas or vapor
Evaporation = vaporization that occurs on the surface of a liquid that is not boiling
Only those molecules with certain minimum kinetic energy can escape from the surface of a liquid
Evaporation rate increases when a liquid is heated…heat increases the average kinetic energy which allows particles to overcome the attractive forces that keep them in the liquid state

35. Vapor   Liquid Vapor/gas Loss in heat Gain in heat Liquid
CONDENSATION
evaporation
Liquid
Gain in heat

36. Vapor Pressure
Vapor pressure = measure of the force exerted by the gas above a liquid
Constant vapor pressure = a dynamic equilibrium exists between the vapor and the liquid. The rate of evaporation = rate of condensation.

37. Animation of Dynamic Equilibrium http://www. mhhe

38. Boiling Liquid in an open container is heated Temperature increases
Particles throughout the liquid have enough kinetic energy to vaporize
The liquid begins to boil
Bubbles of vapor form in the liquid, rise to the surface, and escape into the air
Boiling point = temperature at which the vapor pressure of the liquid = external pressure on the liquid

39. Effect of Pressure On Boiling Point
Lower pressure would lower the boiling point of water.
Water will boil very quickly on the mountain top but the temperature reached is lower than 100oC.
Increasing pressure would raise the boiling point of water.
Water will boil at a higher temperature above 100oC.

40. Normal Boiling Point
Boiling point of a liquid at a pressure of kPa – or standard pressure

41. Melting Heat is applied Particles vibrate as kinetic energy increases
Organization of the solid breaks down
The attractions that hold the particles in fixed positions are overcome
Solid melts
Melting Point = temperature at which a solid melts into a liquid
Freezing Point = Melting Point – they are the same temperature and liquid and solid are in equilibrium

42. Liquid  Solid Loss in heat melting Gain in heat Liquid Solid
FREEZING
melting
Solid
Gain in heat

43. Sublimation
Occurs in solids with vapor pressures that exceed atmospheric pressure at or near room temperature.
A direct change from solid to vapor
Video of Iodine Sublimation

44. Gas   Solid Gas Loss in heat sublimation Gain in heat Solid
deposition
Liquid
sublimation
Solid
Gain in heat

45. Phase Diagrams

46. Phase Diagram
A graph showing the relationships between solid, liquid, vapor states (or phases) of a substance in a sealed container.
Lines on the graph = conditions of pressure and temperature at which two phases exist in equilibrium
Triple point = represents the only set of conditions in which all three phases are present in equilibrium

48. Homework: Interpreting Graphics 13.4 Handout