do now: rank the following phases of matter in order from least to greatest for… a) energy b)...
TRANSCRIPT
DO NOW:Rank the following phases of matter in order from least to greatest for…A) EnergyB) Intermolecular Forces
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 441
High EnergyMedium Energy
Low Energy
WeakIntermolecular
Forces
MediumIntermolecular
Forces
StrongIntermolecular
Forces
Phases/States of Matter
Solid Liquid
Gas
Holds ShapeFixed Volume
Shape of ContainerFree SurfaceFixed Volume
Shape of ContainerVolume of Container
ENERGY ENERGY
SOLID – e.g. ice
Copyright © 2007 Pearson Benjamin Cummings. All rights reserved.
LIQUID – e.g. water
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 31
Gas – e.g. steam
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 31
Some Properties of Solids, Liquids, and Gases
Property Solid Liquid Gas
Shape Has definite shape Takes the shape of Takes the shape the container of its container
Volume Has a definite volume Has a definite volume Fills the volume of the container
Arrangement of Fixed, very close Random, close Random, far apartParticles
Interactions between Very strong Strong Essentially noneparticles
States of Matter
DepositionV
apo
rization
LiquidsThe two key properties we need to describe are
EVAPORATIONEVAPORATION and its opposite CONDENSATIONCONDENSATION
add energy and break intermolecular bondsEVAPORATION
release energy and form intermolecular
bonds
CONDENSATION
Equilibrium is reached when:
1. Rate of Vaporization = Rate of Condensation
2. Molecules are constantly changing phase - dynamic
3. The total amount of liquid and vapor remains constant
solid
liquid
gas
vaporization
condensation
melting
freezing
Heat added
Te
mp
era
ture
(oC
)
A
B
C
DE
Heating Curve for Water
0
100
LeMay Jr, Beall, Robblee, Brower, Chemistry Connections to Our Changing World , 1996, page 487
Heating curve with picturesCreate a curve!!
Triple Point Plot
LeMay Jr, Beall, Robblee, Brower, Chemistry Connections to Our Changing World , 1996, page 488
solidliquid
gas
melting
freezing
sublimation
deposition
vaporization
condensation
Temperature (oC)
Pre
ssur
e (a
tm)
0.6
2.6
1.Calculate the energy required to melt 8.5g of ice at 0°C. The molar heat of fusion for ice is 6.02kJ/mol.
2.Calculate the energy in kJ required to heat 25g of liquid water from 25°C to 100°C and change it into steam at 100°C. The specific heat capacity of liquid water is 4.18J/g°C, and the molar heat of vaporization of water is 40.6kJ/mol.
Calculate the energy required to melt 8.5g of ice at 0°C. The molar heat of fusion for ice is 6.02kJ/mol.
Calculate the energy in kJ required to heat 25g of liquid water from 25°C to 100°C and change it into steam at 100°C. The specific heat capacity of liquid water is 4.18J/g°C, and the molar heat of vaporization of water is 40.6kJ/mol.
Given that the specific heat capacities of liquid water, ice and steam are 4.18J/g°C, 2.06J/g°C & 2.03J/g°C, respectively and considering the molar heats of fusion & vaporization for water are 6.02kJ/mol & 40.6kJ/mol respectively, calculate the total quantity of heat evolved when 10.0 g of steam at 200.°C is condensed, cooled, and frozen to ice at -50°C.
(HINT: 5 step problem!)
Intermolecular Forces
Irresistible attraction…
ATTRACTIVE FORCES
Always electrostatic in nature
Intramolecular forces
bonding forces
These forces exist withinwithin each molecule.They influence the chemicalchemical properties of the substance.
Intermolecular forces nonbonding forces
These forces exist betweenbetween molecules.They influence the physicalphysical properties of the substance.
Intermolecular forces (IMF)• London dispersion forces: The forces that
exist among noble gas atoms and non-polar molecules
• Dipole-dipole attraction: Molecules with dipole moments (polar molecules) can attract each other by lining up so that the positive and negative ends are close to each other.
• Hydrogen bonding: when hydrogen is bonded to a highly electronegative -FON
Dispersion Force
Dispersion forces among nonpolar molecules.
separated Cl2
molecules
instantaneous dipoles
Examples: CO2, Ar, N2
Increase in MM (molar mass) = Increase in London Dispersion Forces
Dipole–Dipole Attractions• Polar molecules have a permanent dipole
– because of bond polarity and shape– dipole moment– as well as the always present induced dipole
• The permanent dipole adds to the attractive forces between the molecules– raising the boiling and melting points relative to
nonpolar molecules of similar size and shape
Polar molecules and dipole-dipole forces.
solid
liquid
Examples: HF, HCl, NH3
H Bond Video
Hydrogen Bonding• When a very electronegative atom is
bonded to hydrogen, it strongly pulls the bonding electrons toward it– O─H, N─H, or F─H
• Because hydrogen has no other electrons, when its electron is pulled away, the nucleus becomes deshielded– exposing the H proton
• The exposed proton acts as a very strong center of positive charge, attracting all the electron clouds from neighboring molecules
H-Bonding
HF
Hydrogen bonding in H2O
• Surface tension
• Capillary action
• Viscosity
Effects of strong intermolecular forces
• Greater IMF = Increase MP &BP, Decrease in Vapor Pressure