ch. 12 - liquids & solids i. intermolecular forces (ch. 6, p.189-193)

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


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



Dipole-Dipole Forces

+ -

View animation online.


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)


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


Capillary Action• attractive force between the surface of

a liquid and the surface of a solid

water mercury


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.


Ionic(NaCl)

Metallic


CovalentMolecular

(H2O)

CovalentNetwork

(SiO2 - quartz)

Amorphous(SiO2 - glass)


Diamond Graphite


III. Changes of State

(p. 372 - 382)

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


Kinetic Energy

# o

f P

art

icle

s

p. 477

Boltzmann Distribution

temp

volatility

IMF

volatility


EquilibriumEquilibrium• trapped molecules

reach a balance between evaporation & condensation


Vapor PressureVapor Pressure• pressure of vapor

above a liquid at equilibrium

• depends on temp & IMF

• directly related to volatility


v.p.temp

IMF v.p.


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?


Melting Point• equal to freezing point

polar

ionic

IMF m.p.


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


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


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


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

ch. 12 - liquids & solids i. intermolecular forces (ch. 6, p.189-193)

Documents

animation slide

atm slide

types of imf slide

phase changes slide

glass slide

temp imf slide

solid watermercury slide

evaporation condensation