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Liquids and Solids
Condensed States of Matter
Solids, Liquids
What is the differencebetween a gas and liquids/solids?•Something to do with density•And volume•And taking the shape of its container•Why?
Why Aren’t All Substances Gases?•Democritus’ theory of atoms was dismissed
because why don’t all these particles fall apart like sand?
• If there is nothing holding molecules together, then they should be free to go where ever. Just like an ideal gas.
Physical Properties
Gas Liquid SolidsHighly Compressible Slightly Slightly
Low Density High Density High Density
Fills Container Definite volume Rigid volume
Assumes Shape Assumes shape Retains own
Rapid diffusion Slow diffusion Extremely Slow,surface
High expansion onheating
Low expansion onheating
Low expansion onheating
Condensed States
•Liquids and Solids•Higher densities than gas Due to lower temperature and attractions
Physical Properties• Gas
▫total disorder▫ freedom of motion▫particles far apart • Solid
▫ordered arrangement▫particles can vibrate▫ remain fixed position▫particles close together•Liquid
•Disorder•free to move relative to each other•particles close
Kinetic-Molecular Theory•The state of a substance depends on the
strength of the attraction between its particles
•And the average kinetic energy (temperature)
•Remember ideal gases do not attract!•Solids and liquids do. •So do “real” gases.
Intramolecular Forces
•Attractions within a molecule – covalent bonds▫Share electrons between nucleii▫Stored energy
Intermolecular ForcesForces between molecules•Dipole-Dipole in polar molecules
▫Strong forces▫Hydrogen Bond are special Dipole-dipole
• Dispersion in non polar▫Explains why non-polar molecules can be
liquids and solids•Van der Waal in long chains
▫Longer chains interact▫Polymers are very long chains, solids
Dipole Dipole Interactions•Dipoles
▫partial negative and partial positive charge
•Partial negative and positive attract▫Dipole - Dipole Forces▫Hydrogen bond - Strongest dipole-dipole
+ - + -
Water
•Water is a polar molecule• It has a positive end and a negative end•Oxygen is negative•Hydrogen is positive•Any time you have oxygen to hydrogen
bond▫Get hydrogen bonding
Hydrogen Bonding
O
HH
-
+
+
O
HH
-
Strong interaction
O
HH
O
H
HO
HH
O
HH
O
H
H
Intermolecular bonds are responsible for the “condensed states
Dispersion Forces
• Induced Dipole▫electron clouds are deformed
•Makes gases “real”
+ -+ -
Induced Dipoles
• When non-polar molecules approach ▫ They negative electron
clouds repel▫ Inducing a dipole▫ Which allows the
molecules to interact
• Helium freezes at 3K▫ Have to move really
slowly to induce a dipole
-300
-250
-200
-150
-100
-50
0
helium
neonargon
krypton
xenon
Freezing Point
van der Waals Forces
Alkane Boiling Points
-170
-70-45
5
35
65
95
125
-200
-150
-100
-50
0
50
100
150
methaneethane
propanebutane
pentane
hexane
heptaneoctane
•The longer the chain, the higher the boiling point
•The chains get tangled like spaghetti
•Takes more energy to break intermolecular tangles
•It has a higher boiling point
Boiling Points
Smaller atoms are more electronegative, so they have more polar bonds. H – bonding is more effective so they have higher boiling points
The higher the molecular weightThe higher the boiling point.Ask why!
Boiling point – • the temperature at which the vapor
pressure equal the atmospheric pressure
•Higher temps = higher kinetic energy•Lower atmospheric pressure requires less
energy
Normal boiling point – the boiling point at 1 atm
Rules for naming organic compounds
1. Find the longest continuous chain2. Number the longest chain to give the
groups/ branches the lowest number possible( left to right or right to left)
3. Add “yl” to prefixes for the groups4. Order groups by alphabet and write
the carbon number they are attached to(use prefixes di, tri, if needed)
Organic prefixes
Prefix number of CMeth 1Eth 2Prop 3But 4Pent 5Hex 6Hept 7Oct 8Non 9Dec 10
Liquids
•Physical properties of liquids are determined mainly by the nature of their intermolecular forces
Liquid Properties
•Viscosity▫How easily a liquid flows.▫Karo syrup vs water▫Cold oil vs hot oil
•Surface tension▫beads of water on a newly waxed car▫soap changes surface tension▫meniscus in graduated cylinder
Surface Tension
•Each water molecule is attracted to its’ neighbor▫In order to move one water▫You have to affect the surrounding
molecules▫The surface doesn’t like to be moved
Has a “tension”
Solids
•Crystalline solid▫particles exist in a highly ordered,
repeating pattern▫form crystals▫Atoms are organized in pattern. ▫One piece = unit cell▫has definite melting point
Solids
•Amorphous solids▫“super cooled liquids▫glass, rubber, many plastics▫gets softer and softer as heated
Solids•Metallic solids - gold, silver•Molecular solids - wax, rubber, plastic•Ionic Solids - sodium chloride•Covalent-network solids - diamond,
graphite
What is the difference between a liquid and a solid?•Liquid flows and a solid is……
▫Solid•What about the molecules?
▫What is difference about them?•Compare interactions between molecules
▫Solid cannot move from neighbor infant
▫Liquid can move, but cannot go anywhere it wants teenager
▫Gas can go anywhere it wants adult
Temp
Time
Freezing. Melting Evaporation, Condensation
Solid Liquid Gas
Heating Curve
Vapor Pressure•What does it mean when something
evaporates?•What does it mean when something boils?•What is vapor pressure?
Kinetic-Molecular Theory of Gases1. Gases have mass and consist of really small particles
2. The volume of a gas atom/molecule is very small compared to the distance to the next atom.
3. Gases particles are in constant and rapid motion. 4. Gas particles collide with themselves and walls of
container in an elastic manner. (They have no interaction with each other)
5. The average kinetic energy of a gas particle is
related to the temperature. Higher temps mean higher kinetic energy and lower temps mean lower KE.
Ideal Gases•Follow the kinetic molecular theory•PV = nRT•Assumptions of KMT are not perfect
▫Gases have intermolecular interactions▫The molecules do take up space
•The molecules interact and eventually this interaction is more than the energy it takes to move away. So they condense or freeze.
Rate of Escape = Rate of Return
Equilibrium
----time-
What is Vapor Pressure?•Gas has mass lab
▫Water has a vapor pressure of 17.2 mmHg@20C
•Pressure is the accumulated collisions▫More molecules mean more collisions
•The warmer the water▫The higher the vapor pressure
Evaporation
•In order for one molecule to escape▫It has to break the intermolecular
attractions▫It has to have enough kinetic energy to
leave▫Why does one molecule have enough
energy to leave and another does not? It has to do with the concept of average
Temperature and Kinetic Energy
• Particles with KE greater that Emin can evaporate.
• More particles can evaporate at higher temperatures(red and blue areas) than at low temperatures (Blue)
Real Gases•Why does a gas condense if there is no
interactions between gas molecules?•We said there is an energy involved in
going from a liquid to a gas. What is it called?▫Heat of evaporation.
•What is the energy involved in freezing?▫Heat of fusion
Atmosphere is exerting pressure or colliding with particles.
When the vapor pressure exceeds atmospheric pressure, it boils
What is Boiling, Freezing, Melting, Freezing?•Heat of Vaporization▫KJ/mol to go from liquid to gas▫Energy to overcome all intermolecular
interactions
•Heat of Fusion▫KJ/mol to go from liquid to solid▫Energy to be able to move past your
neighbor
Heat of evaporation is largeCompared to Heat of fusion
Heating Curve•Energy is exchanged
▫Explain the heating curve in terms of the KMT
▫What happens during the flat parts of the curve?
Temp
Time
Phase Diagrams
Temperature
Pre
ssu
re
solid
gas
liquid
SublimationDeposition
FreezingMelting Evaporation
Condensation
Super critical fluid
Triple Point
The Builderspetrochemicals used to make other substances•Alkenes unsaturated
double bonds•Alkynes unsaturated
triple bonds•Cylcoalkanes/enes saturated or
ring of carbons unsaturatedOxygen hydrocarbons saturated or
C, H, Ounsaturated
Alkenes
Double bond end in eneFollow all rules of naming alkanes plus
number the chain to give the double bond the lowest number possible
Cn H2n
AlkynesTriple bondEnd in yneFollow all the rules of naming alkanes plusnumber the longest chain to give the triple
bond the lowest number possibleCnH2n-2
Cyclic compounds
Ring of carbons, no start or finishBegin cyclo – Follow all the rules of namingCnH2n (same as alkenes)
Oxygenated Hydrocarbons
•All have functional groups▫A atom or group of atoms that give certain
properties to an organic compound
Alcohol, acids, esters, ethers
Alcohols OHname (-e)+ ol
1-methanol1-ethano1- propanol2-propanol
Acids COOH
name(-e) + oic acid
Methanoic acidEthanoic acidPropanoic acid
Water is Weird•Most abundant substance on earth’s
surface•You are 60% water•High heat capacity•High boiling point•Lower density solid than liquid•High surface tension•High heat of vaporization •Universal solvent