Post on 25-Dec-2015
IMF’s, Solids, and LiquidsIMF’s, Solids, and Liquids
Ch. 11 in TextbookCh. 11 in Textbook
msconti.blogspot.com
I. Intermolecular Forces (IMF’s)I. Intermolecular Forces (IMF’s)
attractions between attractions between separateseparate molecules, not bondsmolecules, not bonds
relatively weakrelatively weak occur based on molecular occur based on molecular
polarity and/or chargepolarity and/or charge the strength determines the strength determines
substance’s phase, b.p., m.p., substance’s phase, b.p., m.p., vapor pressure, etc.vapor pressure, etc. itl.chem.ufl.edu
HW: 11.4, 11.6
science.uwaterloo.ca
1. Ion-Dipole Forces (AKA 1. Ion-Dipole Forces (AKA Molecule-Ion Attractions)Molecule-Ion Attractions)
between an ion (full between an ion (full charge) and the charge) and the δδ+ or + or δδ- - of a polar moleculeof a polar molecule
usually the polar usually the polar molecule is water acting molecule is water acting as a solventas a solvent
the greater the the greater the magnitude of the ionic magnitude of the ionic charge and/or the partial charge and/or the partial charges, the stronger the charges, the stronger the IMF’sIMF’s chem.purdue.edu
chemprofessor.com
2.2. van der Waals Forcesvan der Waals ForcesA) Dipole-Dipole ForcesA) Dipole-Dipole Forces
a dipole (2 poles) is a polar a dipole (2 poles) is a polar moleculemolecule
attractions between polar attractions between polar moleculesmolecules
relatively strong, but relatively strong, but technically weaker than ion-technically weaker than ion-dipole forcesdipole forces
the higher the value of the higher the value of μμ (dipole moment), the higher the (dipole moment), the higher the IMF’s (for similar mass/size IMF’s (for similar mass/size molecules)molecules) chemtext.blogspot.com
chem.unsw.edu.au
B) Hydrogen BondingB) Hydrogen Bonding NOT a bondNOT a bond when H is bonded to very EN when H is bonded to very EN
elements (N,O,F, ONLY) a elements (N,O,F, ONLY) a “super dipole” is formed“super dipole” is formed
usually NHusually NH33, H, H22O, and HFO, and HF this leads to unusually high this leads to unusually high
dipole-dipole attractions and dipole-dipole attractions and thus, unusually high b.p.’sthus, unusually high b.p.’s
also results in ice being less also results in ice being less dense than waterdense than water
weren’t you listening, I said it’s weren’t you listening, I said it’s “NOT a bond!”“NOT a bond!”
chemed.chem.wisc.edu
yellowtang.org
C) London Dispersion Forces (AKA C) London Dispersion Forces (AKA Weak Forces)Weak Forces)
occurs between occurs between nonpolarnonpolar molecules molecules
helps when molecules helps when molecules are close to one anotherare close to one another
results from results from momentary/temporary/ momentary/temporary/ induced dipolesinduced dipoles
itl.chem.ufl.edu
the more you can distort an the more you can distort an atom or molecule’s atom or molecule’s electron cloud distribution, electron cloud distribution, the more the more polarizablepolarizable it is it is
larger/massive larger/massive atoms/molecules are more atoms/molecules are more polarizablepolarizable
thus, larger thus, larger atoms/molecules have atoms/molecules have stronger IMF’sstronger IMF’s
ex) halogensex) halogens elmhurst.edu
cactus.dixie.edu
C
NOTE: all molecules have NOTE: all molecules have London dispersion forces!London dispersion forces!
when molecules are of when molecules are of similar size, polarity similar size, polarity determines the strength of determines the strength of IMF’sIMF’s
when molecules differ greatly when molecules differ greatly in size, then polarizability in size, then polarizability determines the strength of determines the strength of IMF’sIMF’s
phys.bspu.unibel.by
HW: 11.8, 11.10, 11.12 (a)-(c), 11.18, 11.22
IMF flow chartIMF flow chart
do activity in lab area do activity in lab area as a group of 4as a group of 4
have chart “Schu have chart “Schu approved”approved”
copy as notescopy as notes
adroll.com
II.II. Properties of LiquidsProperties of Liquids1. Viscosity1. Viscosity
resistance to flowresistance to flow high viscosity- molasses, syruphigh viscosity- molasses, syrup low viscosity- ethanol, waterlow viscosity- ethanol, water based not only on the strength based not only on the strength
of the IMF’s, but also structural of the IMF’s, but also structural features that may cause features that may cause entanglement of moleculesentanglement of molecules
as temp. inc., viscosity dec. due as temp. inc., viscosity dec. due to the breaking of IMF’sto the breaking of IMF’s
syntheticperformanceoil.com
2. Surface Tension2. Surface Tension
due to the imbalance of due to the imbalance of IMF’s within a liquidIMF’s within a liquid
there is a net there is a net downwarddownward pull of surface pull of surface moleculesmolecules
results in results in close packingclose packing of molecules at the of molecules at the surface, forming a surface, forming a “skin”“skin”
fizyka.phys.put.poznan.pl
technically, surface technically, surface tension is defined as the tension is defined as the energy required to energy required to increase the surface area increase the surface area of a liquid by a unit of a liquid by a unit amountamount
units: J/munits: J/m22
quest.nasa.gov
water has a high surface water has a high surface tension due to high tension due to high IMF’sIMF’s
mercury has an even mercury has an even higher surface tension higher surface tension due to metallic bondingdue to metallic bonding
ramehart.com
HW: 11.23
3. Cohesion and Adhesion3. Cohesion and Adhesion
cohesioncohesion = IMF’s between = IMF’s between molecules of the same molecules of the same substancesubstance
adhesionadhesion = IMF’s between = IMF’s between molecules and other molecules and other surfacesurface
although both types of although both types of forces are present, mercury forces are present, mercury has greater cohesive forces has greater cohesive forces than water whereas water than water whereas water has greater adhesive forces has greater adhesive forces than mercurythan mercury
cr4.globalspec.com
4. Capillary Action4. Capillary Action
molecules of liquid rising up molecules of liquid rising up a narrow tubea narrow tube
mechanism = adhesion mechanism = adhesion causes water to stick to tube causes water to stick to tube which increases the surface which increases the surface area; in order to reduce area; in order to reduce surface area, surface tension surface area, surface tension pushes water up tube against pushes water up tube against gravitygravity
ex) chromatography; water ex) chromatography; water in plant rootsin plant roots
cc.gatech.edu
HW: 11.24
III. Phase ChangesIII. Phase Changes
chemistry.wustl.edu
HW: 11.28
1. Heating/Cooling Curves1. Heating/Cooling Curves
physicalweeding.com
heat is ALWAYS being added!heat is ALWAYS being added! when temperature increases, the when temperature increases, the
KE (energy of motion) of the KE (energy of motion) of the particles must be increasing (PE particles must be increasing (PE remains the same)remains the same)
when temperature remains the when temperature remains the same, the KE of the particles same, the KE of the particles must remain the same; thus, PE must remain the same; thus, PE (energy of position) increases as (energy of position) increases as the phase change occursthe phase change occurs
funsci.com
ΔHΔHvapvap > ΔH > ΔHfusfus q = mCΔT used for q = mCΔT used for
calculating heat during calculating heat during temp. changestemp. changes
where where q = heat change in Jq = heat change in Jm = mass in gm = mass in gC = specific heat in C = specific heat in
J/g·K or J/g·ºC J/g·K or J/g·ºC ΔT = temp change ΔT = temp change (T(Tff – – TTii) in K or ºC ) in K or ºC
mrbigler.com
HW: 11.34
2. Vapor and Vapor Pressure2. Vapor and Vapor Pressure vaporvapor = gaseous form of a = gaseous form of a
substance normally found as substance normally found as a liquida liquid
vapor pressurevapor pressure = pressure due = pressure due to vaporto vapor
evaporationevaporation = vaporization of = vaporization of surface molecules of liquidsurface molecules of liquid
boilingboiling = vaporization = vaporization throughout liquid, occurs throughout liquid, occurs when the when the vapor pressure = vapor pressure = atmospheric pressureatmospheric pressure
kidsgeo.com
STORYTIME!STORYTIME!
cityoflawton.ok.us
#1 Water in a Beaker#1 Water in a Beaker
@ room temp and @ room temp and standard pressurestandard pressure
what happens to it?what happens to it?
goldcoast.qld.gov.au
#2 Stoppered Flask of Water#2 Stoppered Flask of Water
@ room temp and @ room temp and standard pressurestandard pressure
what happens to it?what happens to it?
daigger.com
#3 Ethanol Vs. Water#3 Ethanol Vs. Water
@ room temp and standard pressure@ room temp and standard pressure what happens?what happens? volatilityvolatility = the ability to evaporate easily = the ability to evaporate easily
outboardmotoroilblog.com images.veer.com
#4 Heated flask of Water#4 Heated flask of Water
constant heating @ constant heating @ standard pressurestandard pressure
what happens to it?what happens to it? normal boiling pointnormal boiling point = =
temperature at which temperature at which the v.p. of water equals the v.p. of water equals 1 atm (standard 1 atm (standard pressure)pressure)
demo.physics.uiuc.edu
HW: 11.39, 11.42
3. Vapor Pressure Curves3. Vapor Pressure Curves
kentchemistry.comHW: 11.43
4.4. Phase DiagramsPhase Diagrams
from textbook
triple pointtriple point = temp. and = temp. and pressure at which all 3 pressure at which all 3 phases exist in phases exist in equilibriumequilibrium
critical pointcritical point = the = the highest temp. and highest temp. and pressure at which a pressure at which a liquid can existliquid can exist
supercritical fluidsupercritical fluid = = liquid and gas phases liquid and gas phases are indistinguishableare indistinguishable definitiontees.com
HW: 11.36, 11.47, 11.48, 11.50, 11.52
IV.IV. Structures of SolidsStructures of Solids1. Crystalline vs. Amorphous1. Crystalline vs. Amorphous
crystallinecrystalline = well-defined = well-defined arrangement of atoms or arrangement of atoms or molecules (def. attractions = molecules (def. attractions = def. m.p.)def. m.p.)
ex) quartz, diamond, ionic ex) quartz, diamond, ionic solidssolids
amorphousamorphous = no well-defined = no well-defined arrangement of atoms or arrangement of atoms or molecules (indef. attractions = molecules (indef. attractions = softens over temp. range, no softens over temp. range, no distinct m.p.)distinct m.p.)
ex) glass, rubberex) glass, rubber
ndt-ed.org
HW: 11.53
2. Unit Cells2. Unit Cells
unit cellunit cell = the “bricks” = the “bricks” that make up a that make up a crystalline solid; the crystalline solid; the smallest repeating unit smallest repeating unit in a crystal latticein a crystal lattice
fkp.jku.at
A) Primitive CubicA) Primitive Cubic
the lattice points are at the lattice points are at the corners and are the corners and are actually shared by 8 actually shared by 8 atoms!atoms!
1/8 of an atom x 8 1/8 of an atom x 8 corners = 1 atomcorners = 1 atom
ece-www.colorado.edumrsec.wisc.edu
B) Body-Centered CubicB) Body-Centered Cubic
lattice points are at the lattice points are at the corners corners andand at the center at the center
1/8 of an atom x 8 1/8 of an atom x 8 corners + 1 atom = corners + 1 atom = 2 atoms2 atoms
ece-www.colorado.edu
mrsec.wisc.edu
C) Face-Centered CubicC) Face-Centered Cubic lattice points are at the lattice points are at the
corners and each corners and each face/sideface/side
½ of an atom x 6 sides + ½ of an atom x 6 sides + 1/8 atom x 8 corners = 1/8 atom x 8 corners =
4 atoms 4 atoms
ece-www.colorado.edu
mrsec.wisc.edu HW: 11.56, 11.58
3. Bonding in Solids3. Bonding in Solids molecular solidsmolecular solids ionic solidsionic solids metallic solidsmetallic solids covalent-network solids = covalent-network solids =
continuous lattice continuous lattice structure of covalent structure of covalent bonds (no molecules); bonds (no molecules); rigid and dense with high rigid and dense with high m.p.’s (FYI, must break m.p.’s (FYI, must break bonds to melt!)bonds to melt!)
ex) SiOex) SiO22, C (diamond), C , C (diamond), C (graphite), C (buckyballs)(graphite), C (buckyballs)
chem.ufl.edu
HW: 11.69, 11.70
legacy.co.mohave.az.us