CHAPTER 13 Kinetic Molecular Theory (K.M.T.). Kinetic Theory: Kinetic Theory: –The tiny particles...
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Transcript of CHAPTER 13 Kinetic Molecular Theory (K.M.T.). Kinetic Theory: Kinetic Theory: –The tiny particles...
CHAPTER 13CHAPTER 13
Kinetic Molecular TheoryKinetic Molecular Theory(K.M.T.)(K.M.T.)
• Kinetic Theory:Kinetic Theory: – The tiny particles in all forms of matter are The tiny particles in all forms of matter are
in in
constant motion.constant motion.– Explains the properties of solids, liquids, & Explains the properties of solids, liquids, &
gases.gases.
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 volume
2.2. 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. High Density and Incompressibility3. High Density and Incompressibility
4. Low diffusion rate: very slow4. Low diffusion rate: very slow
Crystalline SolidsCrystalline Solids
1. Crystal structure = 3D arrangement 1. Crystal structure = 3D arrangement of particles of crystals.of particles of crystals.
2. Unit Cell = smallest portion of a 2. Unit Cell = smallest portion of a crystal that shows the 3D structure.crystal that shows the 3D structure.
1. no definite shape or volume1. no definite shape or volume2. Particles are small, hard spheres, with 2. Particles are small, hard spheres, with
insignificant volume (very far apart).insignificant volume (very far apart).3. Particles move rapidly in constant 3. Particles move rapidly in constant
random motionrandom motion4. All collisions are perfectly elastic 4. All collisions are perfectly elastic
(Energy is transferred & not lost)(Energy is transferred & not lost)5. There are no forces of attraction or 5. There are no forces of attraction or
repulsionrepulsion between gas particles.between gas particles.
• Gas Pressure:Gas Pressure: is the result of simultaneous is the result of simultaneous collisions of billions of gascollisions of billions of gas
particles with an object.particles with an object.
GASESGASES
• Gas Pressure:Gas Pressure:
is the result of simultaneous collisions of is the result of simultaneous collisions of billions of gas particles with an object.billions of gas particles with an object.
• Vacuum:Vacuum: when no gas particles are when no gas particles are presentpresent
• Atmospheric Pressure:Atmospheric Pressure: results from the results from the collisions of air molecules with objects. collisions of air molecules with objects. Decreases as you climb a mountain b/c air Decreases as you climb a mountain b/c air layer around earth thins out at high layer around earth thins out at high elevations.elevations.
• Barometer:Barometer: measures atmospheric measures atmospheric pressurepressure– SI unit of pressure = pascal (Pa) SI unit of pressure = pascal (Pa) – Atm pressure at sea level = STP (0Atm pressure at sea level = STP (0ooC) =C) =
101.3 kPa = 760 mm Hg= 1 atm= 760 101.3 kPa = 760 mm Hg= 1 atm= 760 torr= torr=
29.92 inHg = 14.7 psi29.92 inHg = 14.7 psi
Ex: 1.50 atm = ? kPaEx: 1.50 atm = ? kPa
1.50 atm 101.3 kPa = 1.52 x 101.50 atm 101.3 kPa = 1.52 x 1022kPakPa
1 atm1 atm
UNITS OF PRESSUREUNITS OF PRESSUREUnitsUnits SymbolSymbol DefinitionDefinition
Millimeters of Millimeters of mercurymercury
mmHgmmHg Pressure of Pressure of that supports that supports 1mm of Hg in 1mm of Hg in a barometera barometer
TorricelliTorricelli torrtorr 1 torr = 1 1 torr = 1 mmHgmmHg
AtmosphereAtmosphere atmatm Average Average atmospheric atmospheric pressure at pressure at sea level at sea level at
00°°CC
PascalPascal PaPa SI Unit for SI Unit for Pressure 1 Pa Pressure 1 Pa
= 1N/m= 1N/m22
BarometersBarometers
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 hence takes the shape of its container.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.
Atmospheric Pressure & Atmospheric Pressure & Boiling PointBoiling Point
• Evaporation (vaporization): Evaporation (vaporization): conversion of a liquid to a gas or vapor conversion of a liquid to a gas or vapor below its boiling point. below its boiling point.
• Vapor Pressure: Vapor Pressure: particles collide with particles collide with the walls of the sealed container. the walls of the sealed container. – Dynamic EquilibriumDynamic Equilibrium
• Boiling Point: Boiling Point: temp. at which the v.p. temp. at which the v.p. of the liquid is just equal to the external of the liquid is just equal to the external pressure. pressure.
Evaporation vs. Boiling Evaporation vs. Boiling
Phase Change DiagramsPhase Change Diagrams
You will see a heat curve for water in You will see a heat curve for water in the next slide.the next slide.
FREEZING, SOLIDIFICATION, CRYSTALLIZATION
MELTING
CONDENSATION
EVAPORATION, VAPORIZATION
DEPOSITION
SUBLIMATION
HEAT OF
FUSION80
cal/g
HEAT OF VAPORIZATION
540 cal/g
Solid
Liquid
Gas
FREEZING, SOLIDIFICATION, CRYSTALLIZATION
MELTING
CONDENSATION
EVAPORATION, VAPORIZATION
DEPOSITION
SUBLIMATION
HEAT OF
FUSION80
cal/g
HEAT OF VAPORIZATION
540 cal/g
Solid
Liquid
Gas