LIQUIDS AND SOLIDSLIQUIDS AND SOLIDS

LIQUIDS:LIQUIDS: Why are they the Why are they the least common state of matter?least common state of matter?1. Liquids and K.M.T.1. Liquids and K.M.T.

Are particles in constant motion? Are particles in constant motion? Spacing?Spacing?

Kinetic Energy? Attractive forces?Kinetic Energy? Attractive forces? FluidFluid: a substance that flows and : a substance that flows and

hence takes the shape of its container.hence takes the shape of its container.

Properties of LiquidsProperties of Liquids

1.1. High DensityHigh Density: 1000x greater than : 1000x greater than gases, 10% less dense than solids.gases, 10% less dense than solids.

2.2. Relatively IncompressibleRelatively Incompressible: Water’s : Water’s volume only decreases 4% under volume only decreases 4% under 1000atm of pressure! 1000atm of pressure!

3.3. Can diffuse:Can diffuse:

Slower in liquids than gases due to:Slower in liquids than gases due to:

slower motion and attractive forces.slower motion and attractive forces.

4.4. Surface TensionSurface Tension: a force that pulls : a force that pulls adjacent parts of a liquid’s surface, adjacent parts of a liquid’s surface, thereby decreasing surface area.thereby decreasing surface area.

Ex: bug “walking” on water.Ex: bug “walking” on water.

CC apillary Action:apillary Action: related to related to surfacesurface

tension; attraction of the surface of tension; attraction of the surface of

a liquid to the surface of a solid.a liquid to the surface of a solid.

Ex: water transport from roots to Ex: water transport from roots to leavesleaves

5.5. Vaporization:Vaporization: Process by which Process by which liquidliquid gas. gas.

EvaporationEvaporation: Process by which : Process by which particles escape from the surface of particles escape from the surface of a nonboiling liquid.a nonboiling liquid.

BoilingBoiling: change of a liquid to vapor : change of a liquid to vapor bubbles appearing throughout the bubbles appearing throughout the liquid.liquid.

SOLIDSSOLIDS1.1. Solids and K.M.T.Solids and K.M.T.

More closely packed than liquids or More closely packed than liquids or gases.gases.

Intermolecular forces are VERY Intermolecular forces are VERY effective.effective.

Only vibrational movement.Only vibrational movement. Crystalline vs. Amorphous (glass) Crystalline vs. Amorphous (glass)

solids.solids.

Properties of SolidsProperties of Solids1.1. Definite shape and volumeDefinite shape and volume2.2. Melting pointMelting point: :

Crystalline SolidsCrystalline Solids: Definite melting point, KE : Definite melting point, KE of particles overcome attractive forces of of particles overcome attractive forces of solid.solid.

Amorphous SolidsAmorphous Solids: No definite melting point, : No definite melting point, Supercooled liquids.Supercooled liquids.

3.3. High Density and IncompressibilityHigh Density and Incompressibility4.4. Low diffusion rate: very slowLow diffusion rate: very slow

Crystalline SolidsCrystalline Solids

1.1. Crystal structure = 3D arrangement Crystal structure = 3D arrangement of particles of crystals.of particles of crystals.

a)a) 7 types of crystals- pg. 3697 types of crystals- pg. 369

2.2. Unit Cell = smallest portion of a Unit Cell = smallest portion of a crystal that shows the 3D structure.crystal that shows the 3D structure.

Binding Forces in CrystalsBinding Forces in Crystals

1.1. Ionic Crystals:Ionic Crystals: NaClNaCl Strong electrostatic forces holds it Strong electrostatic forces holds it

together.together. Hard, brittle, high melting pts.Hard, brittle, high melting pts.

2.2. Covalent Molecular Crystals:Covalent Molecular Crystals: NonpolarNonpolar: H: H22, CH, CH44 vs. vs. PolarPolar: H: H220, NH0, NH33

Covalently bonded molecules held Covalently bonded molecules held together by intermolecular forces.together by intermolecular forces.

Low melting points, soft, easily Low melting points, soft, easily vaporized.vaporized.

3.3. Covalent Network Crystals:Covalent Network Crystals: Diamond (C)Diamond (C)XX , Silicon Carbide (SiC) , Silicon Carbide (SiC)XX

Giant molecules that extend indefinitely- Giant molecules that extend indefinitely- each atom is covalently bonded to each atom is covalently bonded to neighboring atom.neighboring atom.

Hard, Brittle, High Melting PointsHard, Brittle, High Melting Points

4.4. Metallic Crystals:Metallic Crystals: Metal atoms surrounded by sea of valence Metal atoms surrounded by sea of valence

electrons.electrons. High electrical conductivity, Melting Points High electrical conductivity, Melting Points

vary.vary.

Amorphous SolidsAmorphous Solids

1.1. No regular pattern of atoms.No regular pattern of atoms.

2.2. Large range of melting points.Large range of melting points.

3.3. ExamplesExamples: glass, plastics: glass, plastics

EquilibriumEquilibrium

EquilibriumEquilibrium = a dynamic condition in which = a dynamic condition in which 2 opposing changes occur at equal rates in 2 opposing changes occur at equal rates in a closed system.a closed system.

Equilibrium and State Changes:Equilibrium and State Changes:ex: Evaporation of water in a closed ex: Evaporation of water in a closed containercontainer

(assuming constant temp.)(assuming constant temp.)Equilibrium Equations:Equilibrium Equations:

liquid + heat energy vaporliquid + heat energy vapor

Le Chatelier’s PrincipleLe Chatelier’s Principle

When a stress is applied to a system at When a stress is applied to a system at equilibrium, the system will respond in a equilibrium, the system will respond in a way to minimize that stress. (Stress= way to minimize that stress. (Stress= change in temp, pressure, concentration)change in temp, pressure, concentration)

ex: liquid + heat vaporex: liquid + heat vapor

Equilibrium Vapor Pressure of a Equilibrium Vapor Pressure of a LiquidLiquid

The pressure exerted by a vapor in The pressure exerted by a vapor in equilibrium with its liquid at a given temp.equilibrium with its liquid at a given temp.

Increases as temp. increases (How can Increases as temp. increases (How can we explain this using KMT?)we explain this using KMT?)

Volatile vs. Nonvolatile Liquids:Volatile vs. Nonvolatile Liquids:Volatile liquids have WEAK forces of Volatile liquids have WEAK forces of

attraction, therefore they evaporate readily. attraction, therefore they evaporate readily. Ex: ethanolEx: ethanol

Vapor Pressures of varying Vapor Pressures of varying substances at different temps. substances at different temps.

BoilingBoiling The conversion of a liquidThe conversion of a liquid vapor within vapor within

the ENTIRE liquid. Occurs when the the ENTIRE liquid. Occurs when the vapor pressure in the bubble = vapor pressure in the bubble =

atmospheric pressure. atmospheric pressure.

Phase Diagram for WaterPhase Diagram for Water

Critical TemperatureCritical Temperature = Substance can’t exist as a = Substance can’t exist as a liquid above this temperature (only as a gas). liquid above this temperature (only as a gas).

Critical PressureCritical Pressure = Lowest pressure at which the = Lowest pressure at which the substance can exist as a liquid substance can exist as a liquid at the critical at the critical temperature. (any lower P, it’s a gas)temperature. (any lower P, it’s a gas)

Shows the conditions under which the phases of a substance can exist.

Critical Point: indicates the critical temp. and pressure of a substance

Triple Point:Indicates the temp and pressure at which the solid, liquid, gas coexist.