1. Chapter 12 Liquids and Solids

2. 12-1 Definitions!!!!  Fluid- a substance that can flow and therefore take the shape of its container.  Liquids and Gases  Surface Tension- a force that tends to pull adjacent parts of a liquid’s surface together, thereby decreasing surface area to the smallest possible size  Capillary action- the attraction of the surface of a liquid to the surface of a solid (meniscus)

3.  Vaporization- process by which a liquid or solid changes to a gas  Evaporation- process by which particles escape from the surface of a non-boiling liquid and enter the gas state.  Boiling- change of a liquid to vapor.  Freezing- Physical Change of a liquid to a solid by removal of heat. (solidification) Continued……

4. Section Review!!!  Pg. 366 Numbers: 4,5 Surface Tension Surface Tension

5. 12-2  Crystalline Solid- Consist of Crystals  Crystal- a substance in which the particles are arranged in an orderly, geometric, repeating pattern. (see side picture)  Amorphous Solid- particles are arranged randomly, “without Shape”

6.  Melting- physical change of a solid to a liquid by the addition of heat.  Isomorphous- crystals of different solids with the same crystalline structure.  Polymorphous- a single substance having two or more crystalline shapes.  ie: Carbon- graphite, diamond, soot  Hydrated crystal- crystal which contains hydrated ions (H 2 O molecules bonded to ions in the crystals.)

7.  Anhydrous- without water.  Hygroscopic- A dehydrated crystal that will recapture water molecules from the air.  Deliquescent- Substance so hygroscopic that they take up enough water from the air to dissolve and form a liquid.

8. *Known unit cells.  Simple cubic:  Body centered Cubic:  Face centered:

9.  Liquefaction- Condensation of substances that are normally gasses.  Melting point- Temperature at which a solid becomes a liquid.  Super cooled liquids- Substances that retain certain liquid properties even at temperatures at which they appear solid. Ex: Glass  Crystal Structure: Total 3-dimensional arrangement of particles of a crystal  Unit cell- Smallest portion of a crystal lattice That shows the 3-D pattern of the entire lattice - simplest unit of a crystal.

10. 4 Types of Crystals:  1) Ionic- A class of crystals in which the lattice- site occupants are charged ions held together primarily by their electrostatic interaction. electrostatic  2) Covalent network- Giant molecule lattice structures.  3) Metallic- structure that is of metal atoms surrounded by "a sea of valence electrons".  4) Covalent molecular- A molecule is a discrete group of two or more atoms that are held together by covalent bonding

11. 12-3  Equilibrium- Dynamic condition in which two opposing changes occur at equal rates in a closed system.  Phase- Any part of a system that has a uniform composition and properties.  Condensation- Process by which a gas changes to a liquid.  Le Chatelier’s principal- When a system at equilibrium is disturbed by application of a stress, it attains a new equilibrium position that minimizes the stress.  Stress- concentration, pressure, or temp.

12.  Equilibrium vapor pressure- Pressure exerted by a vapor in equilibrium with its corresponding liquid at a given temp.  Volatile liquids- Liquids that evaporate readily.  Boiling- Conversion of a liquid to a vapor.  Boiling point- Temp at which equilibrium vapor pressure of the liquid equals atmospheric pressure.

13.  Normal boiling point of h2o- 100 degrees c, at stp.  Molar heat of vaporization- amount of heat energy needed to vaporize one mole of liquid at its boiling point.  Freezing point- Temp at which the solid and the liquid are in equilibrium.  Molar heat fusion- Amount of heat required to melt one ole of solid at its melting point.

14.  Sublimation- change of state from solid directly to a gas (dry ice)  Deposition- Reverse of sublimation- change from gas directly to solid.  Phase diagram- graph of pressure vs. temp. that shows the conditions under which they phases of the substance exists.

15.  Triple point- indicates the temp. and pressure conditions at which the solid, liquid, and vapor of a substance can coexist.  Critical point- critical temp. and critical pressure.

16.  Critical temp.-(Ct) Temp. above which the substance cannot exist in the liquid state. (Tc=373.99 degree c. for H2o)  Critical pressure- (Cp) lowest pressure at which the substance can exist as a liquid at the critical temp. Pc(H2o)= 217.75 ATM.  Freeze drying- Freezing, lower pressure to cause sublimation.

17. 12-4 water  Most important liquid on earth, 75% of the earth.  Many unique properties due to hydrogen.  Hydrogen bonding- Attractive force, not as strong as an actual bond, between H+ and a (-) pole of another substance.  Water has 4 hydrogen bonds when frozen, very ridged, expands when it melts and can move closer together.  Bond angle between H is 105 degree.

18.  Water has a high heat capacity- highest heat vaporization of any room temp. liquid.  Water is most dense at 4 degrees c. – allows to stay 4 degrees c. on bottom, creates circulation in spring, and fall.  Surfactant- surface active agent= decreases surface tension of h2o by interfering with the H bonding. (soaps, and detergents).