1. Chapter 13 States of Matter 13.2 The Nature of Liquids
13.1 The Nature of Gases
13.2 The Nature of Liquids
13.3 The Nature of Solids
13.4 Changes of State
Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

2. Gases vs. Liquids They are both fluids, substances that can flow
A Model for Liquids
Gases vs. Liquids
They are both fluids, substances that can flow
This allows them to take the shape of their containers
Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

3. A Model for Liquids
Gases vs. Liquids
Kinetic theory assumes there are no attractions between the particles in a gas.
The particles in a liquid are attracted to each other. This keeps the particles close together, which is why liquids have a definite volume.
The physical properties of liquids can be accounted for due to these intermolecular forces.
Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

4. Liquids are much more dense than gases.
A Model for Liquids
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.
Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

5. conversion of a liquid to a gas or vapor.
Evaporation
vaporization
conversion of a liquid to a gas or vapor.
evaporation
Conversion of a liquid to a gas at the surface of a liquid that is not boiling
Molecules with enough kinetic energy escape from the surface of a liquid
Occurs faster with heat
Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

6. Evaporation
Evaporation has a different outcome in an open system, such as a lake or an open container, than in a closed system, such as a sealed container.
In a closed system, the molecules collect as a vapor above the liquid. Some condense back into a liquid.
In an open system, molecules that evaporate can escape from the system.
Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

7. Changes in State
Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

8. Vapor Pressure
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.
vapor pressure: a measure of the pressure/force exerted by a gas above a liquid(at equilibrium)
Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

9. Vapor Pressure
Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

10. Vapor Pressure
At equilibrium,
the rate of evaporation of liquid equals the rate of condensation of vapor.
The pressure exerted by a gas at equilibrium on the liquid is called Vapor Pressure
Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

11. Vapor Pressure and Temperature Change
An increase in the temperature of a contained liquid increases the vapor pressure.
But, Vapor pressure is not affected by surface area of the liquid.
Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

12. Vapor Pressure (in kPa) of Three Substances at Different Temperatures
Interpret Data
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.
Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

13. Vapor Pressure Measurements
The vapor pressure of a liquid can be determined with 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
Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

14. Vapor Pressure Measurements
The vapor pressure is equal to the difference in height of the mercury in the two arms of the U-tube.
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
Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

15. Boiling Point
boiling point - temperature at which the vapor pressure of the liquid is just equal to the external pressure(atmospheric pressure)on the liquid.
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.
Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

16. 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
Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

17. Interpret Graphs
You can use this graph to show how the boiling point of a liquid is related to vapor pressure.
Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

18. Normal Boiling Points of Several Substances
Interpret Data
Normal Boiling Point
- the boiling point of a liquid at a pressure of kPa.
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
Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

19. END OF 13.2
Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.