THE NATURE OF LIQUIDS

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THE NATURE OF LIQUIDS SOLIDS...

• And Stuff

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CONDENSED STATES

• JUST AS GASES CAN, THE PROPERTIES OF LIQUIDS AND
  SOLIDS CAN BE EXPLAINED WITH THE KMT
• LIQUIDS AND SOLIDS ARE GENERALLY MORE DENSE THAN
  GASES
• A.K.A. CONDENSED STATES
• THEIR PARTICLES ARE STILL IN CONSTANT MOTION
• CONDENSED STATES THE PARTICLES ARENT INDEPENDENT
  OF EACH OTHER

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CONDENSED STATES
Low
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CONDENSED STATES
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CONDENSED STATES

• WHAT MAKES A LIQUID A LIQUID OR A SOLID A SOLID?
• WHEN WE COMPRESS A GAS, WHY CAN WE MAKE IT A
  LIQUID OR A SOLID?
• MOLECULES ARE ATTRACTED TO
  EACH OTHER
• THEY TEND
  TO BE STICKY
  TO EACH OTHER

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INTERMOLECULAR FORCES

• THERE ARE FORCES OF ATTRACTION THAT HOLD THE
  MOLECULES TOGETHER IN THE LIQUID OR SOLID STATES
• THERE ARE 3 TYPES OF IMF
• DISPERSION FORCES
• DIPOLE DIPOLE FORCES
• HYDROGEN BONDING
• THESE INTERMOLECULEAR FORCES ARE, ALONG WITH
  ENERGY, THE CONTRIB-UTING FACTORS IN STATE OF
  MATTER

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INTERMOLECULAR FORCES
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DISPERSION FORCES

• THE WEAKEST TYPE OF IMF
• CONNECTED BY TEMPORARY ELECTROSTATIC ATTRACTIONS
• THE CHARGES ARE INDUCED, OR FORCED BY CONTACT
  WITH ANOTHER MOLECULE

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INDUCED DIPOLE INTERACTIONS

• DISPERSION FORCES EXIST BETWEEN ALL MOLECULES
• FORCES INCREASE
  AS MOLECULAR
  WEIGHT INCREASES
• DEPENDANT ON THE
  SHAPE OF THE
  MOLECULE
• MORE SURFACE
  AREA AVAILABLE FOR
  CONTACT, GREATER FORCES

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DIPOLE-DIPOLE FORCES

• ATTRACTION BETWEEN MOLECULES THAT HAVE
  ESTABLISHED PERMANENT DIPOLES
• DIPOLES ARE ESTABLISHED BY INHERENT DIFFERENCES
  IN ELECTRO-NEGATIVITIES
• MOLECULES ARE
  USUALLY ASYMMETRICAL
• STRONGER THAN DISPERSION

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HYDROGEN BONDING

• SPECIAL TYPE OF DIPOLE-DIPOLE IMF
• INTERACTION BETWEEN THE HYDROGEN OF ONE MOLECULE
  FLUORINE, OXYGEN, OR NITROGEN OF ANOTHER
  MOLECULE
• THE HYDROGEN MUST BE ATTACHED DIRECTLY TO AN
  OXYGEN, FLOURINE, OR NITROGEN ATOM
• STRONGER THAN DIPOLE-DIPOLE
  FORCES OR DISPERSION FORCES

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HYDROGEN BONDING
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INTERMOLECULAR FORCES
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INTERMOLECULAR FORCES
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PROPERTIES OF LIQUIDS

• LIQUIDS CAN BE CONNECTED BY ANY OF THE
  INTERMOLECULAR FORCES OR A COMBINATION IMF
• THE STRENGTH OF THE FORCES AFFECT THE LIQUIDS
  PHYSICAL PROPERTIES
• VISCOSITY
• SURFACE TENSION
• CAPILLARY ACTION
• BOILING POINT
• VAPOR PRESSURE

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VISCOSITY

• DEFINED AS THE RESISTANCE TO BEING POURED
• HARDER TO POUR ? HIGHER VISCOSITY
• STRONGER THE INTERMOLECULAR FORCES THE HIGHER THE
  VISCOSITY
• PARTICLES SO ATTRACTED
  TO ONE ANOTHER THEY
  RESIST SLIDING PAST
  EACH OTHER

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SURFACE TENSION

• A PROPERTY COMMON TO ALL LIQUIDS IS SURFACE
  TENSION
• A FORCE THAT TENDS TO PULL ADJACENT PARTS OF A
  LIQUIDS SURFACE TOGETHER, THEREBY DECREASING THE
  SURFACE AREA TO THE SMALLEST POSSIBLE SIZE.
• THE MOLECULES AT THE SURFACE OF A
  LIQUID CLING TO EACH
  OTHER

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SURFACE TENSION

• THE STRONGER THE FORCES OF ATTRACTION BETWEEN THE
  MOLECULES THE STRONGER THE SURACE TENSION
• WATER HAS A RELATIVELY HIGH SURFACE TENSION
  BECAUSE OF ITS HYDROGEN BONDING
• SURFACE TENSION CAUSES WATER TO BEAD
  UP INTO SPHERES THAT REDUCE
  SURFACE AREA

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CAPILLARY ACTION

• THE ATTRACTION OF THE SURFACE OF A LIQUID TO THE
  SURFACE OF A SOLID.
• A LIQUID WILL RISE QUITE HIGH IN A NARROW TUBE IF
  IT HAS STRONG IMFS
• THE ATTRACTION TENDS TO PULL THE LIQUID UPWARD
  ALONG THE SURFACE OF ITS CONTAINER
• STRONGER THE IMF THE
  MORE THE CAPILLARY ACTION

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BOILING POINT

• STRONGER THE IMF THE HIGHER THE BOILING POINT
• THE MORE THE MOLECULES ARE ATTRACTED
  TO EACH OTH-
  ER THE
  MORE
  ENERGY IT
  TAKES TO
  VAPORIZE
  THE LIQUID

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BOILING POINT
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BOILING POINT
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EVAPORATION

• THE LIQUID IN A PUDDLE EVENTUALLY DISAPPEARS,
  AKA EVAPORATION
• THE MOLECULES AT THE SURFACE OF THE LIQUID ESCAPE
  FROM THE PUDDLE INTO THE GASEOUS PHASE
• ONLY THOSE LIQUID MOLECULES WITH ENOUGH ENERGY
  CAN BREAK FREE FROM THE SURFACE
• EVAPORATION ITSELF IS A COOLING PROCESS

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EVAPORATION

• COOLING OCCURS BECAUSE THE PARTICLES WITH THE
  HIGHEST ENERGY ESCAPE LEAVING BEHIND COOLER,
  LOWER ENERGY MOLECULES.

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VAPOR PRESSURE

• WHEN A PARTIALLY FILLED CONTAINER OF A LIQUID IS
  SEALED, SOME OF THE HIGHER ENERGY LIQUID
  PARTICLES VAPORIZE AND BEGIN TO FILL THE SPACE
  ABOVE THE LIQUID
• THESE VAPORIZED PARTICLES COLLIDE WITH THE WALLS
  OF THE SEALED CONTAINER PRODUCING A PRESSURE
  CALLED THE LIQUIDS VAPOR PRESSURE

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VAPOR PRESSURE
SOME OF THE PARTICLES ARE CHANGING FROM A LIQUID
TO A GAS. SOME OF THE PARTICLES ARE CHANGING FROM
A VAPOR TO A LIQUID. THIS CYCLE CONTINUES UNTIL
THE RATES ARE EQUAL
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VAPOR PRESSURE
VAPOR PRESSURE ONLY OCCURS AT EQUILIBRIUM,
THE PARTICLES IN THE SYSTEM CONTINUE TO
EVAPORATE AND CONDENSE, BUT THERE IS NO NET
CHANGE IN THE OF EITHER LIQUID OR VAPOR
PARTICLES
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VAPOR PRESSURE

• THE STRONGER THE IMF THE LOWER THE
  VAPOR PRESSURE
• STRONGER THE IMF THE STICKIER THE MOLECULES
• MORE ENERGY IT TAKES TO VAPORIZE
• FEWER MOLECULES IN VAPOR PHASE

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LIQUID/VAPOR EQUILIBRIUM

• WHEN THE RATE OF VAPORIZATION IS EQUAL TO
  THE RATE OF CONDEN-SATION THE SYSTEM HAS REACHED
  ITS LIQUID/VAPOR EQUILIBRIUM
• ONLY OBSERVED IN A CLOSED
  SYSTEM
• ESTABLISHES A DYNAMIC EQUILIBRIUM
• THE MOLECULES ARE CONSTANTLY EXCHANGING PLACES,
  YET THE RATE OF CHANGE IS THE SAME

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LIQUID/VAPOR EQUILIBRIUM
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WHEN DOES A LIQUID BOIL?

• IN ORDER TO BOIL A LIQUID, THE VAPOR PRESSURE OF
  THE LQUID MUST BE EQUAL TO THE ATMOSPHERIC
  PRESSURE OVER THE LIQUID.
• DONE BY INCREASING THE VAPOR PRESSURE (HEATING
  THE LIQUID)
• OR THIS CAN BE DONE BY DECREASING THE ATMOSPHERIC
  PRESSURE, (PLACING THE LIQUID UNDER A VACCUUM)

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WHEN DOES A LIQUID BOIL?

• THE SECOND OPTION LOWERS THE TEMPERA-TURE AT
  WHICH THE LIQUID BOILS

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WHEN DOES A LIQUID BOIL?
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NATURE OF SOLIDS

• SOLIDS TEND TO CONTAIN PARTICLES THAT ARE
  VIBRATING, BUT ARE RESTRICTED IN THEIR ABILITY TO
  MOVE
• HIGH DENSITY
• DEFINITE VOLUME
• DEFINITE SHAPE
• DEFINITE MELTING POINT
• IMCOMPRESSIBLE
• LOW RATE OF DIFFUSION

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NATURE OF SOLIDS

• SOLIDS DIFFER IN THEIR ARRANGE-MENTS AND IN THE
  FORCES THAT ARE HOLDING THEM IN PLACE.
• TYPES OF ARRANGEMENTS
• CRYSTALLINE
• - CAN BE METALLIC/MOLECULAR/IONIC OR
  COVALENT-NETWORK
• AMORPHOUS

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CRYSTALLINE SOLIDS

• OVERALL STRUCTURE OF A CRYSTALLINE SOLID IS A
  HIGHLY ORDERED, REPEATING PATTERN CALLED UNIT
  CELLS
• A UNIT CELL IS A REPRESENTATIVE UNIT OF
  A LARGER CRYSTAL
• ITS THE SMALLEST REPRESENTATION
  OF THE CRYSTAL

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UNIT CELLS
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CRYSTALLINE SOLIDS
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CRYSTALLINE COVALENT/MOLECULAR

• HELD TOGETHER BY COMBINATIONS OF DIFFERENT
  INTERMOLECULAR FORCES
• MELTING PT IS DEPENDENT ON IMF
• RELATIVELY SOFT
• POOR CONDUCTORS
• SUGAR, ICE,
  DRY ICE

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CRYSTALLINE SOLIDS IONIC

• TIGHTLY PACKED SOLID COMPOSED OF CATIONS ANIONS
• INTRA-MOLECULAR FORCES
• FORM STRONGEST CRYSTAL POSSIBLE
• PACK TO MINIMIZE REPULSIVE FORCES
• ARE HARD AND BRITTLE
• HAVE HIGH MELTING POINTS
• PRODUCE A CRYSTAL WITH A SHAPE DEPENDENT ON IONS
  PRESENT

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CRYSTALLINE METALLIC SOLIDS

• SOLID FORMED BY THE ATTRACTION BETWEEN METAL
  ATOMS AND THE SURROUNDING SEA OF E-S
• ELECTRONS FLOW
• GOOD CONDUCTORS
• DUCTILE AND MALLEABLE
• A MIXTURE OF METALS IS AN ALLOY

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CRYSTALLINE METALLIC SOLIDS
SEA OF ELECTRONS
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COVALENT-NETWORK

• STRONG COVALENT BONDS INVOLVED WITHOUT A
  PARTICULAR MOLECULE BEING FORMED
• FORM A NETWORK OF CONNECTIONS
• THEY HAVE EXTREMELY HIGH MELTING POINTS
• TEND TO BE VERY
  HARD, BUT BRITTLE

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GRAPHITE
DIAMOND VS.
Dispersion Forces
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DIAMOND GRAPHITE
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CRYSTALLINE SOLIDS
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AMORPHOUS SOLIDS

• A SOLID IN WHICH THE PARTICLES ARE ARRANGED
  RANDOMLY
• NO CRYSTAL STRUCTURE
• RIGID APPEAR SOLID-LIKE
• GLASS, RUBBER, PLASTICS
• SOMETIMES CALLED EXTREMELY VISCOUS
  LIQUIDS

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AMORPHOUS SOLIDS
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CHANGES OF STATE...

• And Even More Stuff

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PHASE CHANGE

• A PHASE CHANGE ALWAYS INVOLVES A CHANGE IN ENERGY
• THERE MUST BE ENOUGH ENERGY TO OVERCOME THE
  INTERMOLECULAR FORCES PRESENT
• THE KINETIC ENERGY (VIBRATIONAL ENERGY) IS LARGE
  ENOUGH TO LOOSEN THE FORCES HOLDING THE MOLECULES
  TOGETHER (IMF)
• THE LIQUID TO THE GAS PHASE CHANGE REQUIRES THE
  MOST ENERGY

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PHASE CHANGE
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PHASE DIAGRAMS

• PHASE CHANGES CAN BE DIAGRAMED
• A PHASE DIAGRAM IS A GRAPH OF PRESSURE VERSUS
  TEMPERATURE
• SHOWS THE CONDITIONS UNDER WHICH THE PHASES OF A
  SUBSTANCE EXIST
• THE DIAGRAM REVEALS HOW THE PHASES CHANGE, WITH
  PRESSURE VERSUS TEMPERATURE

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PHASE DIAGRAMS

• IN A TYPICAL PHASE DIAGRAM THERE ARE 3 LINES THAT
  ARE THE BOUNDARY LINES OF THE PHASE CHANGES
• THE LINES SEPARATE THE GRAPH INTO SECTIONS
  LIQUID SECTION SOLID SECTION GAS SECTION

• THE TEMP PRESS AT WHICH THE LINES INTERSECT IS
  CALLED THE TRIPLE POINT
• UNDER THESE CONDITIONS, THE SOLID, LIQUID,
  VAPOR PHASES OF THE SUBSTANCE ARE IN EQUILIBRIUM

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PHASE DIAGRAMS

• THE CRITICAL POINT INDICATES THE TEMPERATURE AND
  PRESSURE OF A SUBSTANCE ABOVE WHICH IT CANNOT
  EXIST IN THE LIQUID STATE.
• WATER HAS A CRITICAL TEMPERATURE OF 373.99C.
  ABOVE THIS TEMP, WATER CANNOT BE LIQUIFIED, NO
  MATTER HOW MUCH PRESSURE IS APPLIED

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PHASE DIAGRAMS
CRITICAL POINT
1
TRIPLE POINT
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PHASE DIAGRAMS