1. Liquids and Solids
Chapter 12

2. Properties of Liquids and the KMT
Liquid- can be described as a form of matter that had definite volume and takes the shape of its container
Fluid- A substance that can flow and therefore takes the shape of its container

3. 6 properties of liquids
Relatively high density- this is a result of the close arrangement of particles
Relative incompressibility- liquids are much less compressible than gases because the particles are more closely packed together
Ability to diffuse- occurs because of the constant random motion of particles

4. Surface tension- a force that tends to pull adjacent parts of a liquid’s surface together
Capillary Action- the attraction of the surface of a liquid to the surface of a solid (root pressure in plants)
Evaporation- a process by which particles escape and enter the gas phase from a non boiling liquid.

5. Vaporization – is the process by which a liquid or solid changes into a gas.
Evaporation is a form of vaporization.
2 examples - perfume & fresh water from oceans

8. Introduction to Solids
When a liquid is cooled, the average energy of its particles decreases
The physical change of a liquid to a solid by removal of heat is called freezing (solidification)
All liquids freeze…but not necessarily at temperatures you normally encounter.

9. Formation of Solids Properties of solids and the KMT
Definite shape and volume-particles are packed closely together compared to liquids and gases.
Definite melting point- the temperature at which a solid becomes a liquid
High density and low compressibility
Low rate of diffusion

10. 2 Types of Solids
Crystalline solids- consists of crystals in which the particles are arranged in an orderly, geometric, repeating pattern
Amorphous solids
-amorphous means “without shape”
-fiberglass, optical fibers, some plastics and glass are amorphous solids

12. Concept Questions Describe the liquid state according to the KMT.
List the properties of liquids.
Why do liquids in a test tube form a meniscus?
Compare vaporization and evaporation.

13. Concept Questions Describe the solid state according to the KMT.
What is the difference between amorphous solid and a crystalline solid?
Why do solids have definite volume, high density and extremely low rates of diffusion?

14. Changes of State
Section 12.3

15. 6 phase changes Solid  liquid melting Solid  gas sublimation
Liquid  solid freezing
Liquid  gas vaporization
Gas  liquid condensation
Gas  solid deposition

17. Equilibrium- a dynamic condition in which 2 opposing changes occur at equal rates in a closed system
Phase- any part of a system that has uniform composition and properties

18. An equilibrium equation
Liquid + heat energy  vapor
Vaporization/evaporation
Vapor  liquid + heat energy
Condensation
Liquid + heat energy  vapor
Liquid-vapor equilibrium

19. What state of matter is (a)? What about (b)?
_________________ is occurring at (c)?

20. Le Chatelier’s Principle
A system will remain at equilibrium until something occurs to change this condition
Le Chatelier’s principle- when a system is disturbed by application of a stress, it attains a new equilibrium position that minimizes stress
Stress- any change in concentration, pressure, or temperature

21. Let’s look again at our equilibrium system…
Liquid + heat energy  vapor
Which direction is the endothermic reaction?
Which direction is the exothermic direction?

22. Equilibrium Shifts CHANGE SHIFT Adding liquid Removing liquid
Adding vapor
Removing vapor
Decrease volume
Increase volume
Decrease temperature
Increase temperature

23. Volatile and Nonvolatile Liquids
Volatile liquids- liquids that evaporate readily
Nonvolatile liquids- evaporate slowly, have strong attractive forces between particles

24. Boiling
Boiling point-conversion of a liquid to a vapor within the liquid as well as at its surface.

25. Freezing and Melting
Freezing point- the temperature at which the solid and liquid are in equilibrium at 1 atm pressure

26. Stop

27. Phase Diagrams
Phase diagrams- a graph of pressure versus temperature that shows the conditions under which the phases of a substance exist
Triple point- indicates the temperature and pressure conditions at which the solid, liquid, and vapor of the substance can coexist at equilibrium

28. Critical temperature- the temperature above which the substance cannot exist in the liquid state
Water °C
Critical pressure- the lowest pressure at which the substance can exist as a liquid at the critical temperature
Water atm

30. At 6 atm, what is the boiling point of carbon dioxide?

31. Stop

32. Water Water is the Earth’s most abundant liquid
Oceans, rivers, and lakes cover about 75% of the earth’s surface
70-90% of the mass of living things is water

33. Structure of Water
The molecules in solid or liquid water are linked by hydrogen bonding
Ice consists of water molecules in a hexagonal arrangement. The empty spaces between molecules in this pattern accounts for the low density of ice
Once the molecule is heated, water molecules can crowd closer together
Thus, liquid water is denser than ice.

34. Physical Properties of Water
Pure liquid water is transparent, odorless, tasteless, and almost colorless
Any observable impurities are caused by dissolved minerals, liquids, or gases
It has a unique property of expanding in volume when it freezes
This explains why ice floats in water.

36. Molar heat of vaporization
It is a measure of the attraction between the particles of a liquid
Molar heat of fusion (H)- Depends on the attraction between the solid particles

37. Calculating Molar Heat
q = m (H)
q = heat (J)
m = mass (g)
Hvaporization H2O = 2260 J/g
Hfusion H2O = 334 J/g

38. Practice Problems
How much heat energy is absorbed when 47.0 g of ice melts at STP? How much heat energy is absorbed when this same mass of liquid water boils?
What quantity of heat energy is released when 506 g of liquid water freezes?
What mass of steam is required to release 4.97 x 105 kJ of heat energy on condensation?