1. States of Matter Ch.13 Section 1: The Nature of Gases
Section 2: The Nature of Liquids
Section 3: The Nature of Solids
Section 4: Changes of State

2. What does the word Kinetic Refer to?
Section 13.1
What does the word Kinetic Refer to?
Kinetic energy – the energy an object has because of its motion.

3. Kinetic Theory
According to the kinetic theory, all matter consists of tiny particles that are in constant motion.
PhET Simulation for States of Matter Basics

4. Kinetic Theory and a Model for Gases
The particles in a gas are considered to be small, hard spheres with an insignificant volume.
The motion of particles in a gas is rapid, constant, and random.
All collisions between particles in a gas are perfectly elastic.

5. The particles in a gas are considered to be small, hard spheres with an insignificant volume.
Within a gas, the particles are relatively far apart compared with the distance between particles in a liquid or solid.
Between the particles, there is empty space.
No attractive or repulsive forces exist between the particles.

6. The motion of particles in a gas is rapid, constant, and random.
Gases fill their containers regardless of the shape and volume of the containers.
An uncontained gas can spread out into space without limit.
Bromine molecule

7. The motion of particles in a gas is rapid, constant, and random.
The rapid, constant motion of particles in a gas causes them to collide with one another and with the walls of their container.

8. The motion of particles in a gas is rapid, constant, and random.
The particles travel in straight-line paths until they collide with another particle.
The particles change direction only when they rebound from collisions.

9. All collisions between particles in a gas are perfectly elastic.
During an elastic collision, kinetic energy is transferred without loss from one particle to another.
The total kinetic energy remains constant.
Review Key Concepts again with simulation.
PhET Simulation for States of Matter Basics

10. Describe an elastic collision between gas molecules.
An elastic collision is one in which kinetic energy is transferred from one particle to another with no overall loss of kinetic energy.

11. How does kinetic theory explain gas pressure?
Gas pressure results from the force exerted by a gas per unit surface area of an object.
Gas pressure is the result of billions of rapidly moving particles in a gas simultaneously colliding with an object.
Moving bodies exert a force when they collide with other bodies.
If no particles are present, no collisions can occur. Consequently, there is no pressure
An empty space with no particles and no pressure is called a vacuum.

12. Air Pressure
Air exerts pressure on Earth because gravity holds the particles in air within Earth’s atmosphere.
The collisions of atoms and molecules in air with objects results in atmospheric pressure.
Atmospheric pressure decreases as you climb a mountain because the density of Earth’s atmosphere decreases as the elevation increases.

14. Gas Pressure
A barometer is a device that is used to measure atmospheric pressure.
At sea level, air exerts enough pressure to support a 760-mm column of mercury.
On top of Mount Everest, at 9000 m, the air exerts only enough pressure to support a 253-mm column of mercury.

15. When weather forecasters state that a low-pressure system is moving into your region, it usually means that a storm is coming. What do you think happens to the column of mercury in a barometer as a storm approaches? Why?
When a storm approaches, the column of mercury goes down, indicating a decrease in atmospheric pressure.

16. The SI unit of pressure is the pascal (Pa).
One standard atmosphere (atm) is the pressure required to support 760 mm of mercury in a mercury barometer at 25°C.
The numerical relationship among the three units is
1 atm = 760 mm Hg = kPa.
Recall that standard temperature and pressure (STP) are defined as a temperature of 0°C and a pressure of kPa, or 1 atm.

17. Converting between units of pressure
Sample Problem 13.1
Converting between units of pressure
A pressure gauge records a pressure of 450 kPa. Convert this measurement to
a. atmospheres
b. millimeters of mercury
Ans.
A.) 4.4 atm
B.) 3.4x10^3 mm Hg
Conversion factor:
1 atm = 760 mm Hg = kPa.

18. Converting between units of pressure Additional Problems
What pressure, in kilopascals and in atmospheres does a gas exert at 385 mm Hg?
Answer kPa, atm

19. Converting between units of pressure Additional Problems
The pressure at the top of Mount Everest is kPa. Is that pressure greater or less than atm?
33.7 kPa is greater than 0.25 atm

20. Converting between units of pressure Additional Problems
What pressure, in mm Hg and atm, does a sample of neon gas exert at 75.0 kPa?
563 mm Hg, atm

21. Converting between units of pressure Additional Problems
What pressure, in mm Hg and kPa, does a sample of argon gas exert at atm?
1186 mm Hg, kPa

22. What is the pressure in millimeters of mercury inside a vacuum?
0 mm Hg

23. Kinetic Energy & Temperature
As a substance is heated, its particles absorb energy, some of which is stored within the particles.
This stored portion of the energy, or potential energy, does not raise the temperature of the substance.
The remaining absorbed energy does speed up the particles, that is, increases their kinetic energy.
This increase in kinetic energy results in an increase in temperature.

24. As a substance is heated, the particles tend to move faster, and their average kinetic energy increases.
As a substance cools, the particles tend to move more slowly, and their average kinetic energy decreases.
Notice that the molecules at the higher temperature have a wider range of kinetic energies.

25. Compare the shapes of the curves for cold H2O and hot H2O.
What would happen to the shape of the curve if the water temperature were even higher? Even lower?
Compare the shapes of the curves for cold H2O and hot H2O.
Which point on each curve represents the average kinetic energy?
A.) a point near the peak of the curve
B.) The curves have the same overall shape, but the curve for hot water is wider with a lower peak.
C.) At an even higher temperature, the graph would be wider than the red curve with a lower peak; at an even lower temperature, the graph would be narrower than the blue curve with a higher peak.

26. Kinetic Energy & Temperature
Absolute zero (0 K, or –273.15oC) is the temperature at which the motion of particles theoretically ceases.
STOP for Absolute Zero: PBS Nova film
No temperature can be lower than absolute zero.
Absolute zero has never been produced in the laboratory

27. Were you paying attention?
1. According to the kinetic theory, the particles in a gas
are attracted to each other.
are in constant random motion.
have the same kinetic energy.
have a significant volume.

28. Were you paying attention?
2. The pressure a gas exerts on another object is caused by
the physical size of the gas particles.
collisions between gas particles and the object.
collisions between gas particles.
the chemical composition of the gas.

29. Were you paying attention?
3. The average kinetic energy of the particles in a substance is directly proportional to the
Fahrenheit temperature.
Kelvin temperature.
molar mass of the substance.
Celsius temperature.

30. Were you paying attention?
4. What is the results of increasing the temperature of a gas sample?
A decrease in the average kinetic energy of the sample
No effect on the sample
An increase in the average kinetic energy of the sample
The particles slow down.

31. The Kinetic Molecular Theory Postulates
Gases particles are in a state of constant, random motion.
Gas particles travel in a straight line until they collide with another particle or the walls of the container.
Gas particles are compressible
volume is negligible.
no force of attraction or repulsion between gas particles
Energy is conserved during collisions
Gases are composed of many particles that behave like hard, spherical objects in a state of constant, random motion.
These particles move in a straight line until they collide with another particle or the walls of the container.
These particles are much smaller than the distance between particles, therefore the volume of a gas is mostly empty space and the volume of the gas molecule themselves is negligible.
There is no force of attraction between gas particles or between the particles and walls of the container.
Collisions between gas particles or collisions with the walls of the container are elastic. That is, none of the energy of the gas particles is lost in a collision

32. Bell Ringer When brewing coffee, identify the solvent and the solute.
What factors may affect coffee brewing results?
The ratio of water-to-coffee
Particle size of the coffee beans
The temperature of the water
The amount of time water and coffee are in contact with each other
Why is coffee brewed with hot water?
Water is a better solvent at hot, or near-boiling temperatures.
Explain that in the brewing process, water acts as a solvent. The water passes through the coffee grounds, dissolving soluble solids as it goes, and into the brew. The non-soluble solids remain in the filter. Grinding the coffee increases the surface area of the coffee. A greater surface area increases the rate at which the natural oils in coffee will evaporate. Over grinding the beans will heat the oils also causing them to evaporate.

33. DATE: 9/30/2014
Bell Ringer
Compare and contrast; what is the difference between evaporation and boiling?
Misconception: Many students use the terms boiling and evaporation interchangeably. Explain that boiling is different from evaporation because evaporation can occur at any temperature, whereas boiling occurs at specific temperatures and pressures.

34. Section 13.2
A Model for Liquids
Substances that can flow are referred to as fluids.
The ability of gases and liquids to flow allows them to conform to the shape of their containers.
Both liquids and gases can flow.

35. Why are liquids not as easily compressible and gases are?
Indefinite shape; flows
Fixed volume
Almost incompressible
Indefinite shape; flows
Indefinite volume; takes the shape of its container
Easily compressed
Why are liquids not as easily compressible and gases are?
According to kinetic theory, there are no attractions between the particles in a gas.
The particles in a liquid are attracted to each other.
- These intermolecular attractions keep the particles in a liquid close together

36. Sinks = more dense Floats = less dense
Indefinite shape; flows
Fixed volume
Almost incompressible
Indefinite shape; flows
Indefinite volume; takes the shape of its container
Easily compressed
Liquids are much more dense than gases.
Increasing the pressure on a liquid has hardly any effect on its volume.
The same is true for solids.
Liquids and solids are known as condensed states of matter.
Sinks = more dense
Floats = less dense

37. Evaporation
The conversion of a liquid to a gas or vapor (heat must be added)is called vaporization.
When this conversion occurs at the surface of a liquid that is not boiling (no heat applied), the process is called evaporation.
In an open system, molecules that evaporate can escape from the system.
In a closed system, the molecules collect as a vapor above the liquid. Some condense back into a liquid.
Recall: what is the difference between a vapor and a gas?

38. Evaporation
During evaporation, only those molecules with a certain minimum kinetic energy can escape from the surface of the liquid.
As evaporation occurs, the particles with the highest kinetic energy tend to escape first.
Even some of the particles that do escape collide with molecules in the air and rebound back into the liquid.

39. Evaporation A liquid evaporates faster when heated.
Heating the liquid increases the average kinetic energy of its particles.
The added energy enables more particles to overcome the attractive forces keeping them in the liquid state.
Evaporation is a cooling process
The particles left in the liquid have a lower average kinetic energy than the particles that have escaped.
As evaporation takes place, the liquid’s temperature decreases. When you perspire, water molecules in your perspiration absorb heat from your body and evaporate from the skin’s surface. This evaporation leaves the remaining perspiration cooler.

40. Vapor Pressure
The evaporation of a liquid in a closed system differs from evaporation in an open system.
When a partially filled container of liquid is sealed, some of the particles at the surface of the liquid vaporize.
These particles collide with the walls of the sealed container, producing pressure.
A measure of the force exerted by a gas above a liquid is called vapor pressure.

41. Vapor Pressure
Over time, the number of particles entering the vapor increases and some of the particles condense and return to the liquid state.
Liquid Vapor (gas)
evaporation
condensation
Eventually, the number of particles condensing will equal the number of particles vaporizing.

43. Vapor Pressure
In a system at constant vapor pressure, a dynamic equilibrium exists between the vapor and the liquid. The system is in equilibrium because the rate of evaporation of liquid equals the rate of condensation of vapor.
At equilibrium, the particles in the system continue to evaporate and condense, but no net change occurs in the number of particles in the liquid or vapor.

44. Vapor Pressure
Vapor Pressure and Temperature Change
An increase in the temperature of a contained liquid increases the vapor pressure.
This happens because the particles in the warmed liquid have increased kinetic energy.
More of the particles will reach the minimum kinetic energy necessary to escape the surface of the liquid.

45. Vapor Pressure
Vapor Pressure and Temperature Change

46. Vapor Pressure (in kPa) of Three Substances at Different Temperatures
Vapor Pressure and Temperature Change
The vapor pressure data indicates how volatile a given liquid is, or how easily it evaporates.
Vapor Pressure (in kPa) of Three Substances
at Different Temperatures
Substance
0°C
20°C
40°C
60°C
80°C
100°C
Water
0.61
2.33
7.37
19.92
47.34
101.33
Ethanol
1.63
5.85
18.04
47.02
108.34
225.75
Diethyl ether
24.70
58.96
122.80
230.65
399.11
647.87
Of the three liquids shown, diethyl ether is the most volatile and water is the least volatile.
Answer the following questions: a.) Infer: at a given temperature, ethanol has a higher vapor pressure than water. What does that say about the relative strength of attraction between particles of each substance? B.) Draw Conclusions: How does an increase in temperature affect a compound’s ability to evaporate?

47. Vapor Pressure
Vapor Pressure Measurements
The vapor pressure is equal to the difference in height of the mercury in the two arms of the U-tube.
The vapor pressure of a liquid can be determined with a device called a manometer.
12.2 mm Hg or 1.63 kPa
43.9 mm Hg or 5.85 kPa
Air at standard temperature and pressure
Ethanol at 0°C
Ethanol at room temperature (20°C)
Air
Mercury
Ethanol

48. Were you paying attention?
In a sealed gas-liquid system at a constant temperature, eventually
there will be no more evaporation.
the rate of condensation decreases to zero.
the rate of condensation exceeds the rate of evaporation.
the rate of evaporation equals the rate of condensation.

49. Teacher Demo Vapor Pressure Water vs. rubbing alcohol
Observe & infer which liquid has the greater vapor pressure at room temperature and explain their reasoning.
Use cotton balls to simultaneously dab spots of water and rubbing alcohol onto the chalkboard. Have the class observe what happens to the spots.

50. Boiling Point
When a liquid is heated to a temperature at which particles throughout the liquid have enough kinetic energy to vaporize, the liquid begins to boil.
Bubbles of vapor form throughout the liquid, rise to the surface, and escape into the air.
The boiling point (bp) is the temperature at which the vapor pressure of the liquid is just equal to the external pressure on the liquid.

51. Chemistry and You
Why does it take longer to cook food in water at higher altitudes?
Why does food take less time to cook in a pressure cooker?
Q.1: because atmospheric pressure decreases with altitude, water boils at a lower temperature and the food doesn’t cook as quickly.
Q.2: In a pressure cooker the pressure can be greater than atmospheric pressure. Thus, the boiling point of water can be higher, and the food takes less time to cook.

52. Boiling Point & Pressure Changes
Because a liquid boils when its vapor pressure is equal to the external pressure, liquids don’t always boil at the same temperature.
Because atmospheric pressure is lower at higher altitudes, boiling points decrease at higher altitudes.

53. Boiling Point and Pressure Changes
Atmospheric pressure at the surface of water at 70°C is greater than its vapor pressure. Bubbles of vapor cannot form in the water, and it does not boil.
At the boiling point, the vapor pressure is equal to the atmospheric pressure. Bubbles of vapor form in the water, and it boils.
At higher altitudes, the atmospheric pressure is lower than it is at sea level. Thus, the water boils at a lower temperature.
101.3 kPa
34 kPa
70°C
100°C
Sea Level
Atop Mount Everest

54. At a higher external pressure, the boiling point increases.
Interpret Graphs
At a higher external pressure, the boiling point increases.
You can use this graph to show how the boiling point of a liquid is related to vapor pressure.
Utilize Reference Table Workbook assignment for Table H
At a lower external pressure, the boiling point decreases.

55. Boiling is a cooling process close to evaporation
The vapor produced is at the same temperature as that of the boiling liquid.
Although the vapor has the same average kinetic energy as the liquid, its potential (or stored) energy is much higher.
Thus, a burn from steam is more severe than one from an equal mass of boiling water, even though they are both at the same temperature.

56. Normal Boiling Points of Several Substances
The is defined as the boiling point of a liquid at a pressure of kPa. normal boiling point
Normal Boiling Points of Several Substances
Substance
Boiling Point (°C)
Carbon disulfide (CS2)
46.0
Chloroform (CHCl3)
61.7
Methanol (CH4O)
64.7
Carbon tetrachloride (CCl4)
76.8
Ethanol (C2H6O)
78.5
Water (H2O)
100.0

57. Is the boiling point of water at the top of Mount McKinley (the highest point in North America) higher or lower than it is in Death Valley (the lowest point in North America)?
The boiling point of water decreases as altitude increases. Therefore, the boiling point of water is lower atop Mount McKinley than it is in Death Valley.

58. Were you paying attention?
In liquids, the attractive forces are
very weak compared with the kinetic energies of the particles.
strong enough to keep the particles confined to fixed locations in the liquid.
strong enough to keep the particles from evaporating.
strong enough to keep particles relatively close together.

59. Were you paying attention?
Which one of the following is a process that absorbs energy?
freezing
condensation
evaporation
solidifying

60. Were you paying attention?
In a sealed gas-liquid system at constant temperature, eventually with boiling
there will be no more evaporation.
the rate of condensation decreases to zero.
the rate of condensation exceeds the rate of evaporation.
the rate of evaporation equals the rate of condensation.

61. Were you paying attention?
Where must particles have enough kinetic energy to vaporize for boiling to occur?
at the surface of the liquid
at the bottom of the container
along the sides of the container
throughout the liquid

62. Were you paying attention?
The boiling point of a liquid
increases at higher altitudes.
decreases at higher altitudes.
is the same at all altitudes.
decreases as the pressure increases.

63. 13.3 The Nature of Solids
The general properties of solids reflect the orderly arrangement of their particles and the fixed locations of their particles.
In most solids, the atoms, ions, or molecules are packed tightly together.
Solids are dense and not easy to compress.
Because the particles in solids tend to vibrate about fixed points, solids do not flow.

64. Allotropes Some substances can exist in more than one form.
Allotropes – 2 or more different molecular forms of the SAME element in the SAME physical state. Ex.
Diamond
Graphite
Fullerene

65. 13.3 – The Nature of Solids Allotropes
The arrangement and location of its particles affect the general properties of a solid.
Diamond vs. Graphite vs. Fullerene
Same element, BUT different structures = different physical & chemical properties

66. Bell-Ringer
Please duplicate the graph to the right in your bell-ringer.
Identify if this is an endothermic or exothermic curve.
Identify on the curve where the heating of a solid, liquid, and gas occur.
Identify where the phase changes occur by the processes that occur there.
Identify whether the kinetic energy and potential energy is increase, decreasing, or remaining constant for each of the segments on the graph.

67. The Nature of Solids Changes of State
Section 13.3
Section 13.4
The Nature of Solids
Changes of State
Students were instructed to just read the section and complete the workbook.
No critical information in section.
Students were instructed to just read the section, complete the workbook, and answer the textbook questions.
Only critical information was phase change diagram, of which the phase diagram packet was used for instruction. The phase diagram for H2O was explained, walking through labeling melting point, boiling point, triple point, critical point, equilibrium, what happens to temperature when pressure is increased and decreased, etc.