I. Kinetic Molecular Theory KMT

Assumptions 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 Model  op_KMT_frames.htm op_KMT_frames.htm  Click on the link above to see how particles of matter behave according to the KMT.

Liquids & Solids II. Intermolecular Forces

Definition of IMF  Attractive forces between molecules.  Much weaker than chemical bonds within molecules.  a.k.a. van der Waals forces

Types of IMF  London Dispersion Forces View animation online.animation

Types of IMF  Dipole-Dipole Forces + + - - View animation online.animation

Types of IMF  Hydrogen Bonding

Types of IMF

Ion-Dipole  Attraction between an Ion and a polar covalent bond (dipole)  IMF responsible for salts dissolving in water.  Strength determines salt solubility.

III. Physical Properties Liquids & Solids

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

Liquid Properties  Surface Tension attractive force between particles in a liquid that minimizes surface area

Liquid Properties  Capillary Action attractive force between the surface of a liquid and the surface of a solid watermercury

Types of Solids  Crystalline - repeating geometric pattern covalent network metallic ionic covalent molecular  Amorphous - no geometric pattern decreasing m.p.

Types of Solids Ionic (NaCl) Metallic

Types of Solids Covalent Molecular (H 2 O) Covalent Network (SiO 2 - quartz) Amorphous (SiO 2 - glass)

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”  Defn – rule used to determine if substance will dissolve in another - based on attractive forces between solute and solvent

Solubility  Defn – max amt of solute that can dissolve in a solvent at a specific temp how much solute can be put into solvent?

Unsaturated Solution  Defn – less than max amt of solute dissolved if I put sugar into water and all sugar is dissolved, solution is unsaturated

Saturated 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 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) Curve represents max amount solute allowed Temperature Solubility (g solute/ 100 g H 2 O) Unsaturated (below line) Saturated (above line)

Solubility 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 Soluble  The following ions are always soluble, no matter what the other ion is. Group IA (Li, Na…) Ammonium (NH 4 + ) Nitrates (NO 3 - ) Chlorates (ClO 3 - ) Acetates (C 2 H 3 O 2 - )

Almost always soluble  Halides (Cl, Br…) Except for fluorides Except for silver, mercury(I) and lead  Sulfates Except for barium, calcium, lead, mercury(I)

Mostly insoluble  Hydroxide (OH-) Except for barium, strontium and calcium (these ARE soluble along with the always soluble ions)  Sulfides, carbonates, chromates, and phosphates.