Ch. 12 - Liquids & SolidsCh. 12 - Liquids & SolidsCh. 12 - Liquids & SolidsCh. 12 - Liquids & Solids

I. Intermolecular Forces

(Ch. 6, p.189-193)

A. Definition of IMFA. Definition of IMF

Attractive forces between molecules.

Much weaker than chemical bonds within molecules.

B. Types of IMFB. Types of IMF

B. Types of IMFB. Types of IMF

London Dispersion Forces

View animation online.

Attractive forces that arise as a result of temporary dipoles induced in atoms or molecules

11.2

ion-induced dipole interaction

dipole-induced dipole interaction

B. Types of IMFB. Types of IMF

B. Types of IMFB. Types of IMF

Dipole-Dipole Forces

+ -

View animation online.

B. Types of IMFB. Types of IMF

Hydrogen Bonding

C. Determining IMFC. Determining IMF

NCl3• polar = dispersion, dipole-dipole

CH4

• nonpolar = dispersionHF

• H-F bond = dispersion, dipole-dipole, hydrogen bonding

II. Physical Properties

(p. 363 - 371)

Ch. 12 - Liquids & SolidsCh. 12 - Liquids & SolidsCh. 12 - Liquids & SolidsCh. 12 - Liquids & Solids

A. Liquids vs. SolidsA. Liquids vs. Solids

LIQUIDS

Stronger than in gases

Y

high

N

slower than in gases

SOLIDS

Very strong

N

high

N

extremely slow

IMF Strength

Fluid

Density

Compressible

Diffusion

A. Liquids vs. SolidsA. Liquids vs. Solids

A phase is a homogeneous part of the system in contact with other parts of the system but separated from them by a well-defined boundary.

B. Liquid PropertiesB. Liquid Properties

Surface Tension• attractive force between

particles in a liquid that minimizes surface area

B. Liquid PropertiesB. Liquid Properties

Capillary Action• attractive force between the surface of

a liquid and the surface of a solid

water mercury

B. Liquid PropertiesB. Liquid Properties

Adhesion

Cohesion

Maximum Density40C

Density of Water

11.3

Water is a Unique Substance

C. Types of SolidsC. Types of Solids

Crystalline - repeating geometric pattern• covalent network• metallic• ionic• covalent molecular

Amorphous - no geometric pattern

decreasingm.p.

C. Types of SolidsC. Types of Solids

Ionic(NaCl)

Metallic

C. Types of SolidsC. Types of Solids

CovalentMolecular

(H2O)

CovalentNetwork

(SiO2 - quartz)

Amorphous(SiO2 - glass)

C. Types of SolidsC. Types of Solids

Diamond Graphite

C. Types of SolidsC. Types of Solids

Ch. 12 - Liquids & SolidsCh. 12 - Liquids & SolidsCh. 12 - Liquids & SolidsCh. 12 - Liquids & Solids

III. Changes of State

(p. 372 - 382)

A. Phase ChangesA. Phase Changes

A. Phase ChangesA. Phase Changes

EvaporationEvaporation• molecules at the surface gain enough

energy to overcome IMF

VolatilityVolatility• measure of evaporation rate• depends on temp & IMF

Eva

pora

tion

GreatestOrder

LeastOrder

Con

dens

atio

nT2 > T1

A. Phase ChangesA. Phase Changes

Kinetic Energy

# o

f P

art

icle

s

p. 477

Boltzmann Distribution

temp

volatility

IMF

volatility

A. Phase ChangesA. Phase Changes

EquilibriumEquilibrium• trapped molecules

reach a balance between evaporation & condensation

A. Phase ChangesA. Phase Changes

Vapor PressureVapor Pressure• pressure of vapor

above a liquid at equilibrium

• depends on temp & IMF

• directly related to volatility

A. Phase ChangesA. Phase Changes

v.p.temp

IMF v.p.

A. Phase ChangesA. Phase Changes

Boiling Point• temp at which v.p. of liquid

equals external pressure

IMF b.p.Patm b.p.

• depends on Patm & IMF

• Normal B.P. - b.p. at 1 atm

Which has a higher m.p.?• polar or nonpolar?• covalent or ionic?

A. Phase ChangesA. Phase Changes

Melting Point• equal to freezing point

polar

ionic

IMF m.p.

A. Phase ChangesA. Phase Changes

Sublimation

• solid gas

• v.p. of solid equals external pressure

EX: dry ice, mothballs, solid air fresheners

B. Heating CurvesB. Heating Curves

Melting - PE

Solid - KE

Liquid - KE

Boiling - PE

Gas - KE

B. Heating CurvesB. Heating Curves

Heat of Vaporization (Hvap)

• energy required to boil 1 gram of a substance at its b.p.

• usually larger than Hfus…why?

EX: sweating, steam burns, the drinking bird

B. Heating CurvesB. Heating Curves

Temperature Change• change in KE (molecular motion) • depends on heat capacity

Heat Capacity• energy required to raise the temp of 1

gram of a substance by 1°C

B. Heating CurvesB. Heating Curves

Phase Change• change in PE (molecular arrangement)• temp remains constant

Heat of Fusion (Hfus)

• energy required to melt 1 gram of a substance at its m.p.

C. Phase DiagramsC. Phase Diagrams

Show the phases of a substance at different temps and pressures.

C. Phase DiagramsC. Phase Diagrams