1. CHAPTER 12 LIQUIDS and SOLIDS

2. Liquids – the least common state of matter in the universe
Liquids exist at relatively narrow ranges of temperature and pressure

3. Liquid Particles have less KE than gas particles
Properties of Liquids
Particles are in constant motion
Particles are much closer together than gases
Liquid Particles have less KE than gas particles
Attractive forces between particles are strong enough they can not be ignored (dipole-dipole, London dispersion and hydrogen bonds)
Movement is more limited than in gases due to these attractive forces

4. Properties of Liquids
Definite Volume- volume can only be changed slightly by temp & pressure.
Fluidity- particles have ability to flow past one another.
Relatively High Density – most are thousands of times denser as liquids than as gases (solids are only slightly more dense than liquids).
Relatively Incompressible – even at very high pressure and low temperature liquids compress only slightly because the particles are already so close together.

5. Ability to diffuse- particles will mix uniformly with one another but at a much slower rate than gases.
Surface Tension– A force that tends to pull adjacent parts of a liquid’s surface together due to attractive forces between particles.
Capillary Action- The attraction of the surface of a liquid to the surface of a solid
Vaporization - Liquid or solid changing to a gas, evaporation is the change of state from a non-boiling substance.
Boiling- Change of a liquid to bubbles of vapor (different from vaporization though)

6. Liquid – Molecules have Enough Kinetic Energy to Slide Past One Another.

7. Formation of Solids: When KE is low enough that attractive forces hold particles in fixed positions, the particles become solid.
Freezing/solidification- the physical change from a liquid to solid by removing heat.

8. pg 366 q 1-5
HOME FUN

9. SOLID AS A ROCK
SOLIDS

10. Solids have less KE than either liquids or gases.
Molecules are tightly packed and intermolecular forces are strongly exerted. Particles are held in a relatively fixed position.
Two types of Solids: Crystalline and Amorphous

11. Crystalline solids: consist of crystals (substance in which the particles are arranged in an orderly, geometric, repeating pattern
Amorphous solids: one in which the particles are arranged
randomly

12. PROPERTIES of SOLIDS Definite shape and volume Definite melting point
Melting: solid to liquid by addition of heat
Melting point: temp at which a solid becomes a liquid
Supercooled liquids: substances that retain certain liquid properties even at temperature at which they appear to be solid. (Amorphous solids.. Might they be called liquids that do not flow?)

13. PROPERTIES OF SOLIDS
High density and incompressibility- particles are more densely packed
Very Very Low rate of diffusion-
Rate of diffusion depends upon: ____________
Temperature: As temperature increases, the kinetic energy of the particles increases so the speed of particles also increases which thus increases the rate of diffusion.
Mass of the particle: As the mass of particle increases, rate of diffusion decreases.

14. Crystalline Solids
Crystal structure: total three-dimensional arrangement of particles of a crystal.
Unit cell: smallest portion of a crystal lattice that shows the three-dimensional pattern of the entire lattice. The unit cells are then repeated to make the crystal.
There are seven basic crystalline systems.
See Figure page 369

15. Binding forces in Crystals
ionic crystals – Positive and negative ions arranged in a regular pattern. Ex: NaCl, KOH,MgF2
Properties include: hard, brittle, high melting points, good insulators.
covalent network crystals – Each atom is covalently bonded to its neighboring atom. Essentially giant molecules. Ex: diamond, SiO2, SiC
Properties include: high melting points, nonconductors or semiconductors, hard and brittle.
metallic crystals – Sea of electrons model. Electrons belong to the entire crystal. Properties: high conductivity, melting points vary greatly
covalent molecular crystals -- Covalently bonded molecules that are held together by intermolecular forces (Van der Waals).
Properties: low melting point, soft, good insulators, easily vaporized.

16. Amorphous Solids Amorphous – Greek.. without shape
Do not have a regular natural shape, but can hold their shape for a long time.
Solids that flow
Ex: Glass, rubber and plastics

17. HOME FUN
pg 371 q 1-4

18. CHANGES of STATE
Equilibrium - dynamic condition in which 2 opposing changes occur at equal rates in a closed system. A dynamic equilibrium occurs when you have a reversible reaction in a closed system. Nothing can be added to the system or taken away from it apart from energy. In other words, the system must be closed.
Phase: any part of a system that has uniform composition and properties. Ex: liquid phase, gas phase, solid phase.

19. Trapped molecules reach a balance between evaporation & condensation
Equilibrium
Trapped molecules reach a balance between evaporation & condensation
An increase in condensation = An increase in evaporation

20. Examples of Changes of State
Change of State
Process
Example
solid  liquid
melting
ice  water
solid  gas
sublimation
dry ice  CO2 gas
liquid  solid
freezing
water  ice
liquid  gas
vaporization
liquid Br  Br vapor
gas  liquid
condensation
water vapor  water
gas  solid
deposition
water vapor  ice

21. A system will remain at equilibrium until something occurs to change this condition.
Le Chatelier’s principle- when a system at equilibrium is disturbed by application of a stress, it attains a new equilibrium. Stressors include changes in:
1. concentration
2. pressure
3. temperature
A change in equilibrium is called a shift in equilibrium.

22. Equilibrium Vapor Pressure
Equilibrium Vapor Pressure (EVP) -The pressure exerted by a vapor in equilibrium with its corresponding liquid at a given temperature.
Equilibrium vapor pressure of a liquid increases as temperature increases but not in direct proportion
Increasing temp of liquid increases average kinetic energy; thus, increasing the number of molecules that have enough energy to escape from the liquid phase
Increased evaporation rate increases the concentration of molecules in the vapor phase increasing the equilibrium vapor pressure.
Every liquid has a specific EVP at a given temp (like having specific b.p. & f.p.)

23. Volatile & Nonvolatile liquids
Volatile Liquids- evaporate readily, have weak intermolecular forces. Ex: ether, alcohol, ammonia.
A substance with a high equilibrium vapor pressure at normal temperatures is often referred to as volatile.
Nonvolatile Liquids – evaporate slowly due to stronger bonding.

24. Molar Heat of Vaporization
Boiling - conversion of a liquid to a vapor within the liquid, as well as at its surface.
boiling point (b.p.) of a liquid is the temp at which EVP equals the atmospheric pressure.
Boiling occurs when EVP = atm. pressure
Boiling point is dependent on atmospheric pressure.
The lower the atmospheric pressure is, the lower the boiling point is.
At the boiling point, all of the heat absorbed goes to evaporate the liquid
Molar Heat of Vaporization
The amount of heat that is required to vaporize one mole of liquid at its boiling point.
Water has an unusually high heat of vaporization

25. Freezing and Melting Molar Heat of Fusion
Freezing Point-Melting point
The temperature at which the solid and liquid
are at equilibrium at 1 atm pressure.
At this point the solid and liquid have the same average KE.
Molar Heat of Fusion
The amount of heat that is required to melt one mole of solid at its melting point.
The structural order of the particles decrease in as energy is added.

26. Sublimation and Deposition
sublimation - change of a solid directly to a gas (dry ice)
deposition - change of a gas directly to a solid (formation of frost on a cold surface)
Dry ice
iodine

27. During any change of state, the temp will remain constant until the change of state is complete.
water melts at 0oC and freezes at 0oC
a glass of ice water at 0oC will always have the same amt. of ice and water!
even if heat is added to the system, the water/ice solution will remain at 0oC until all the ice is melted, then its temp will increase.
Same goes for boiling

28. Phase Diagrams Pressure vs. Temperature
Triple point - indicates the temp and pressure conditions at which a solid, liquid and gas can coexist at equilibrium.
Critical temperature (tc) - the temp above which the substance cannot exist in liquid state.
Critical pressure (Pc) - the lowest pressure required for a substance to exist as a liquid at critical temp
Pc of H2O = atm
Pressure vs. Temperature
Indicates the conditions under which gaseous, liquid, and solid phases of a particular substance exist. (pg 381)
Along AB line: rate at which solid sublimes to form a gas = rate at which gas condenses to form a solid
Along BC line: rate at which liquid boils to form a gas = rate at which gas condenses to form a liquid
Along BD line: rate at which solid melts to form a liquid = rate at which liquid freezes to form a solid
Phase Diagrams

29. Home Fun
Pg 382 q 1-8
Read ch12-4 Water
Pg 386 q 1-4

32. Water Water Everywhere