I. Kinetic Molecular Theory

KMT

I. Kinetic Molecular Theory

KMT

Assumptions of KMTAssumptions of KMT

•All matter is composed of tiny particles

•These particles are in constant, random motion.

•Some particles are moving fast, some are moving slowly.

•Temperature is a measure of the average Kinetic Energy and is proportional to the average speed of the molecules.

KMT ModelKMT Model

http://preparatorychemistry.com/Bishop_KMT_frames.htm

Click on the link above to see how particles of matter behave according to the KMT.

Liquids & SolidsLiquids & SolidsLiquids & SolidsLiquids & Solids

II. Intermolecular ForcesII. Intermolecular Forces

Definition of IMFDefinition of IMF

Attractive forces between molecules.

Much weaker than chemical bonds within molecules.

a.k.a. van der Waals forces

Types of IMFTypes of IMF

London Dispersion Forces

View animation online.

Types of IMFTypes of IMF

Dipole-Dipole Forces

+ -

View animation online.

Types of IMFTypes of IMF

Hydrogen Bonding

Types of IMFTypes of IMF

Ion-DipoleIon-Dipole

Attraction between an Ion and a polar covalent bond (dipole)

IMF responsible for salts dissolving in water.

Strength determines salt solubility.

III. Physical PropertiesIII. Physical Properties

Liquids & SolidsLiquids & SolidsLiquids & SolidsLiquids & Solids

Liquids vs. SolidsLiquids 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

Liquid PropertiesLiquid Properties

Surface Tension• attractive force between particles in a

liquid that minimizes surface area

Liquid PropertiesLiquid Properties

Capillary Action• attractive force between the surface of

a liquid and the surface of a solid

water mercury

Types of SolidsTypes of Solids

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

Amorphous - no geometric pattern

decreasingm.p.

Types of SolidsTypes of Solids

Ionic(NaCl)

Metallic

Types of SolidsTypes of Solids

CovalentMolecular

(H2O)

CovalentNetwork

(SiO2 - quartz)

Amorphous(SiO2 - glass)

Solvation In Aqueous Solutions

Solvation In Aqueous Solutions

Solvation – process of surrounding solute particles with solvent particles

Why are some substances soluble in a solvent and some others are not?

must be compatibility between solute and solvent

“like dissolves like”“like dissolves like”

Defn – rule used to determine if substance will dissolve in another

- based on attractive forces between solute and solvent

SolubilitySolubility

Defn – max amt of solute that can dissolve in a solvent at a specific temp

how much solute can be put into solvent?

Unsaturated SolutionUnsaturated Solution

Defn – less than max amt of solute dissolved

if I put sugar into water and all sugar is dissolved, solution is unsaturated

Saturated SolutionSaturated Solution

Defn – contains max amt of solute dissolved

if I put sugar into water and not dissolves (you can see the sugar), the solution is saturated

Supersaturated SolutionSupersaturated Solution

Defn – contains more solute than saturated solution at the same conditions

a saturated solution made at high temp cools slowly. Slow cooling allows excess solute to remain dissolved in solution at lower temperature

very unstable

Solubility Curve (generic)Solubility Curve (generic)

Curve represents max amount solute allowed

Temperature

Solu

bili

ty(g

solu

te/

10

0 g

H2O

)

Unsaturated(below line)

Saturated(above line)

Solubility RulesSolubility Rules

Some ions always form water soluble compounds.

Other ions always form water insoluble compounds

The rest are sometimes water soluble and sometimes insoluble

Always SolubleAlways Soluble

The following ions are always soluble, no matter what the other ion is.• Group IA (Li, Na…)

• Ammonium (NH4+)

• Nitrates (NO3-)

• Chlorates (ClO3-)

• Acetates (C2H3O2-)

Almost always solubleAlmost always soluble

Halides (Cl, Br…)• Except for fluorides• Except for silver, mercury(I) and lead

Sulfates• Except for barium, calcium, lead,

mercury(I)

Mostly insolubleMostly insoluble

Hydroxide (OH-)

• Except for barium, strontium and calcium (these ARE soluble along with the always soluble ions)

Sulfides, carbonates, chromates, and phosphates.