DO NOW: Rank the following phases of matter in order from least to greatest for… A) Energy B) Intermolecular Forces Zumdahl, Zumdahl, DeCoste, World of.

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