Principles of Chemistry Exam 2

KMT 1- Gases consist of ____ constantly moving randomly in space at various speeds

Particles

KMT 2- The average kinetic energy of gas particles is proportional to _____________

Temperature in kelvin

KMT 3- Molecular collisions are elastic: when molecules collide, they _______ kinetic energy (keeping it constant)

Exchange

KMT 4- ____ particles have no volume

Gas

KMT 5- There are no __________ between gas particles

Attractive forces

KMT 6- Molecules collide with the ___________; these collisions constitute the pressure of the gas

Walls of their container

Ideal gases

The 6 assumptions of the KMT

Real Gases (Characteristics)

• Atoms occupy some volume

• There are forces of attraction between atoms or molecules

Pressure

Force per unit area exerted against a surface

1 atm = 760 mm Hg, 760 torr

Boyle’s Law (definition + formula)

For a fixed mass at a constant temp, volume is inversely proportional to pressure (P1V1=P2V2)

Charles’ Law (definition + formula)

For a fixed mass at a constant pressure, volume is directly proportional to temp in K (V1/T1=V2/T2)

Gay-Lussac’s Law

For a fixed mass at a constant temp, pressure is directly proportional to temp in K (P₁/T₁=P₂/T₂)

Combined Gas Law

P₁V₁/T₁ = P₂V₂/T₂

Avogadro’s Law

Equal volumes of gas at the same temp + pressure have the same amount of molecules

Standard Temperature + pressure

0*C (273K), 1atm, 22.4L/mole

Ideal Gas Law

PV= nRT

Dalton’s Law of Partial Pressure

P_Total= P₁+P₂+P₃….

2 Intramolecular forces

Ionic bonds

Covalent bonds

3 Intermolecular forces

Hydrogen bonds

Dipole-Dipole

London Dispersion Forces

Intramolecular forces are between

Atoms

Intermolecular forces are between

Molecules

London Dispersion Forces (characteristics)

• Between all molecules

• In NP molecules, it’s the only attractive force

• Caused by a temporary dipole

• Strength increases as mass and # of e^- increase

Dipole-Dipole (characteristics)

• Attraction between + and - dipoles

• Stronger than LDF

Hydrogen Bonds (characteristics)

• Noncovalent force between H and N/O

• Strongest intermolecular force

Density of a liquid _ density of a gas (> or <)

>

Surface Tension

Layer on the surface of a liquid caused by uneven intermolecular attractions at the surface

Vapor Pressure of a liquid

When partial pressure of the vapor is at equilibrium with the liquid (if T increases, so does VP)

Boiling Point

Temp at which the vapor pressure of a liquid = the atmospheric pressure

List in order of highest → lowest BP

Dipole-Dipole

Hydrogen Bonds

LDP

Hydrogen Bonds

Dipole- Dipole

LDF

Boiling Point Depends on 3 factors

• IMF (low IMF= low bp)

• Molecular weight

• Molecular shape

Crystalization

Formation of a solid from a liquid

Phase

Any part of a system that looks uniform

Phase change

A change from one state of matter to another

Solutions are made of

Solvents and solutes

Solvent

Fraction of solution in which other components are dissolved/ put into

Solute

Substance that is dissolved in a solvent to make a solution

Particle distribution of solutions is _______

Uniform

Components of a solution do not _______ on standing (should stay dissolved)

Separate

Solutions cannot be separated by _______

Filtration

It is _______ to make solutions of many different component

Possible

Solutions are almost always _________ (except for solid solutions)

Transparent

Solubility

Maximum amount of solute that dissolves in a given amount of solvent at a given temperature

Low solubility= _____

High solubility= ______

Insoluble, soluble

Saturated solution

Solvent contains the maximum amount of solute that can be held

Unsaturated solution

Solvent contains less than the max amount of solute that can be held

Super saturated

Solution is above solubility limit

Solubility of solids in liquids ______ as temperature increases

Increases

Solubility of gases in liquids _______ as temperature increases

Decreases

Solubility of gasses increases when _____ increases

Pressure

Percent Composition: Weight of solute per volume of solution (weight = grams, v = mL)

weight solute/volume solution x 100

Percent Composition: Weight of solute per weight of solution (weight = grams)

Weight solute/weight solution x 100

Percent Composition: Volume of solute per volume of solution (volume = mL)

Volume solute/volume solution x 100

Molarity (M)

Moles of solution (n)/ liters of solution (L)

Dilution formula

M₁V₁ = M₂V₂

Parts per million (ppm)

Could be w/w, w/v, or v/v. Units must MATCH

Mass solute/ mass solution x 10⁶

Parts per billion (ppb)

Could be w/w, w/v, or v/v. Units must MATCH

Mass solute/ mass solution x 10⁹

Negative regions of ____ attract the positive regions of water

Ions

Ions dissolved in water are called _____

Hydrated

Cations (pos. ions) migrate toward negative electrode called

Cathode

Anions (neg. ions) migrate toward positive cathode called

Anode

Electrolyte

Substance that conducts an electrical current when dissolved in water (cations + anions)

Strong electrolyte

Compound that dissociates completely into ions in an aqueous solution

Weak electrolyte

Compound that only partially dissociates in an aqueous solution

Colloids (2 characteristics b/c of large surface areas)

• Scatter light → appear cloudy/milky

• Form stable dispersions, do not settle out of a solution

Colloid solute particle diameter is between _______

1 and 1000 nm

Suspensions

Have particles with diameters larger than 1000 nm, particles eventually settle out of the solution

Colligative Properties

Any property of a solution that depends on the number of solute particles (not their nature)

3 Examples of colligative properties

• Freezing point depression

• Boiling point elevation

• Osmosis

Freezing point depression equation (answer is subtracted from 0*C)

ΔT= 1.86*C/1 mol x mol of particles

Boiling point elevation equation (answer is added to 100*C)

ΔT_b= 0.512*C/ 1 mol x mol of particles

Osmosis

The movement of solvent particles through a semi-permeable membrane from low solute concentration to high

Osmolarity

M (molarity) x i (# of particles produced by each formula unit of solute)