1. The States of Matter

3. States of Matter There are 4 states of matter.
A solid is a form of matter that has its own definite shape and volume.

4. Solids A solid cannot flow.
The particles can vibrate but cannot move around.
The particles of matter in a solid are very tightly packed; when heated, a solid expands, but only slightly.

5. Liquids
A liquid is a form of matter that flows, has constant (definite) volume, and takes the shape of its container.

6. Liquids
The particles in a liquid are not rigidly held in place and are less closely packed than are the particles in a solid; liquid particles are able to move past each other.

7. Liquids A liquid is not very compressible.
Like solids, liquids tend to expand when heated.

8. Gases
A gas is a form of matter that flows to conform to the shape of its container and fills the entire volume of its container.

9. Gases
Compared to solids and liquids, the particles of gases are very far apart.
Because of the significant amount of space between particles, gases are easily compressed.

11. States of Matter
Plasma is composed of electrons and positive ions at temperatures greater than °C. The sun and other stars are examples of plasma.

12. Definite Volume? Definite Shape? Solid Liquid Gas Expansion with heat?
Com-pressible?
Small Expans.
Solid
YES
YES NO
Small Expans.
Liquid NO NO
YES
Large Expans.
Gas NO NO
YES

13. Question
Identify the following as a property of a solid, liquid or gas. The answer may include more that one state of matter.
1. flows and takes the shape of a container
liquid, gas

14. Question
Identify the following as a property of a solid, liquid, or gas. The answer may include more that one state of matter.
2. compressible
gas

15. Question
Identify the following as a property of a solid, liquid, or gas. The answer may include more that one state of matter.
3. made of particles held in a specific
arrangement
solid

16. Question
Identify the following as a property of a solid, liquid, or gas. The answer may include more that one state of matter.
4. has definite volume
solid, liquid

17. Question
Identify the following as a property of a solid, liquid, or gas. The answer may include more that one state of matter.
5. always occupies the entire space of its container
gas

18. Question
Identify the following as a property of a solid, liquid, or gas. The answer may include more that one state of matter.
6. has a definite volume but flows
liquid

19. States of Matter
The word vapor refers to the gaseous state of a substance that is a solid or a liquid at room temperature.
For example, steam is a vapor because at room temperature water exists as a liquid.

20. Matter
Some substances are described as volatile, which means that they change to a gas easily at room temperature.
Alcohol and gasoline are more volatile than water.

21. Liquids
Kinetic-molecular theory predicts the constant motion of the liquid particles.
Individual liquid molecules do not have fixed positions in the liquid.

22. Liquids
However, forces of attraction between liquid particles limit their range of motion so that the particles remain closely packed in a fixed volume.
These attractive forces are called intermolecular forces.
Inter = between
Molecular = molecules

23. Liquids
A liquid diffuses more slowly than a gas at the same temperature, however, because intermolecular attractions interfere with the flow.

24. Liquids Viscosity is a measure of the resistance of a liquid to flow.
Viscosity decreases with increasing temperature.

25. Liquids
Particles in the middle of the liquid can be attracted to particles above them, below them, and to either side.
For particles at the surface of the liquid, there are no attractions from above to balance the attractions from below.

26. Liquids
Thus, there is a net attractive force pulling down on particles at the surface.
Surface tension is a measure of the inward pull by particles in the interior.

27. Liquids

28. Liquids
Soaps and detergents decrease the surface tension of water by disrupting the hydrogen bonds between water molecules.

29. Solids
For a substance to be a solid rather than a liquid at a given temperature, there must be strong attractive forces acting between particles in the solid.

30. Solids
These forces limit the motion of the particles to vibrations around fixed locations in the solid. Thus, there is more order in a solid than in a liquid.
The particles can only vibrate and revolve in place.

31. Solids
Because of this order, solids are much less fluid than liquids and gases. In fact, solids are not classified as fluids.
Most solids are more dense than most liquids.

32. Crystalline Solids
A crystalline solid is a solid whose atoms, ions, or molecules are arranged in an orderly, geometric, three-dimensional structure.
Most solids are crystals.

33. Amorphous Solids Amorphous solids lack an orderly internal structure.
Think of them as supercooled liquids.
Examples of amorphous solids include rubber and glass.

34. Condensation
Freezing
Deposition
Sublimation
Vaporization
Melting
Solid
Liquid
Gas

35. Heating Curve for Water
Section D:
Water is
Boiling.
Section A:
Ice is being heated
to the melting
point.
Section C:
Water is
being heated
to the boiling
point.
Section B:
The ice
is melting.
Section E:
Steam is
being heated.

36. PHASE CHANGES

37. ????
Vaporization
Solid
Liquid
Gas
Condensation
????

38. Vaporization
If a substance is usually a liquid at room temperature (as water is), the gas phase is called a vapor.
Vaporization is the process by which a liquid changes into a gas or vapor.
Vaporization is an endothermic process - it requires heat.

39. Vaporization
When vaporization occurs only at the surface of an uncontained liquid (no lid on the container), the process is called evaporation.

40. Evaporation Molecules at the surface break away and become gas.
Only those with enough kinetic energy (KE) escape.
Evaporation is a cooling process.
It requires heat, which is endothermic.

41. Vapor Pressure
Vapor pressure is the pressure exerted by a vapor over a liquid.
As temperature increases, water molecules gain kinetic energy and vapor pressure increases.

42. Boiling
When the vapor pressure of a liquid equals atmospheric pressure, the liquid has reached its boiling point, which is 100°C for water at sea level.
Recall that standard atmospheric pressure equals 1 atm.

43. Boiling
At this point, molecules throughout the liquid have the energy to enter the gas or vapor phase.
The temperature of a liquid can never rise above its boiling point.

44. Boiling Boiling is an endothermic process.
It requires the addition of heat.

45. Changing the Boiling Point
As you go up into the mountains (increase in elevation), atmospheric pressure decreases.
Lower external pressure requires lower vapor pressure.

46. Changing the Boiling Point
Lower vapor pressure means lower boiling point.
As a result, spaghetti cooks slower in the mountains than at the beach.

47. Changing the Boiling Point
When you use a pressure cooker to can vegetables, the external pressure around the mason jars rises.

48. Changing the Boiling Point
This raises the vapor pressure needed in order for water to boil.
In turn, the boiling point is raised so the food cooks faster.

49. Condensation
Some phase changes release energy into their surroundings.
For example, when a vapor loses energy, it may change into a liquid.

50. Condensation
Condensation is the process by which a gas or vapor becomes a liquid. It is the reverse of vaporization.

51. Dynamic Equilibrium
In a closed system, the rate of vaporization can equal the rate of condensation.

52. Dynamic Equilibrium
When first sealed, the molecules gradually escape the surface of the liquid.
As the molecules build up above the liquid, some condense back to a liquid.

53. Dynamic Equilibrium Rate of Vaporization = Rate of Condensation
Equilibrium is reached when
Rate of Vaporization =
Rate of Condensation

54. Dynamic Equilibrium
Molecules are constantly changing phase - “Dynamic”
The total amount of liquid and vapor remains constant - “Equilibrium”

55. Melting
????
Solid
Liquid
Gas
Freezing
????

56. Melting
The melting point of a solid is the temperature at which the forces holding the particles together are broken and the solid becomes a liquid.
When heated the particles vibrate more rapidly until they shake themselves free of each other.

57. Freezing
The freezing point is the temperature at which a liquid becomes a crystalline solid.
The freezing point is the same as the melting point.

58. ????
Sublimation
Solid
Liquid
Gas
Deposition
????

59. Sublimation
The process by which a solid changes directly into a gas without first becoming a liquid is called sublimation.
Solid air fresheners and dry ice are examples of solids that sublime.

60. Deposition
When a substance changes from a gas or vapor directly into a solid without first becoming a liquid, the process is called deposition.
Deposition is the reverse of sublimation.
Frost is an example of water deposition.

61. Question
Classify the following phase change.
1. dry ice (solid carbon dioxide) to carbon dioxide gas
sublimation

62. Question
Classify the following phase change.
2. ice to liquid water
melting

63. Question
Classify the following phase change.
3. liquid water to ice
freezing

64. Question
Classify the following phase change.
4. water vapor to liquid water
condensation

65. PHASE DIAGRAMS

66. Phase Diagrams
Temperature and pressure control the phase of a substance.
A phase diagram is a graph of pressure versus temperature that shows in which phase a substance exists under different conditions of temperature and pressure.

67. Phase Diagrams
A phase diagram typically has three regions, each representing a different phase and three curves that separate each phase.

68. Phase Diagrams

69. Phase Diagrams
The points on the curves (the red, blue and yellow lines) indicate conditions under which two phases coexist.

70. Phase Diagrams
The critical point indicates the critical pressure and the critical temperature above which a substance cannot exist as a liquid.

71. Phase Diagrams
The triple point is the point on a phase diagram that represents the temperature and pressure at which three phases of a substance can coexist.

72. Phase Diagrams
The negative slope of the solid-liquid line in the phase diagram for water indicates the the solid floats on its liquid.

73. Question
What happens to solid carbon dioxide at -100 ºC and 1 atm pressure as it is heated to room temperature?
(The dry ice sublimes to CO2 gas.)

74. Question
What happens to water at 1 atm as the temperature rises from -15°C to 60°C?
(It melts.)

75. Question
What state of matter is water at 50°C and 20 atm?
(liquid)

76. At what temperature does the triple point occur for water?
Question
At what temperature does the triple point occur for water?
(0.0098°C)
0.0098

77. Question
At what temperature does the critical point occur for carbon dioxide?
(31°C)

78. Question
At standard pressure and -78°C, what phase changes can occur for carbon dioxide?
(sublimation and deposition)

79. Question
What state of matter is carbon dioxide at -80°C and 2 atm?
(solid)