chem 2 exam 1

london dispersion

present in all molecules, weakest strength, increases with higher molar mass and surface area, temporary attraction caused by random electron movement, increases with # of electrons

dipole dipole

polar molecules, caused by uneven electron distribution

hydrogen bonding

polar molecules with a hydrogen bonded to an NOF

ion-dipole

ionic and polar compounds

intermolecular forces

act between particles in a substance

state of matter dependent on

intermolecular forces at play and amount of heat it contains

gas

indefinite shape and volume, low density, weak IMF

liquid

indefinite shape, definite volume, high density, medium IMF

solid

definite shape and volume, high density, strongest IMF

surface tension

the tendency of liquids to minimize their surface area, increases with IMF

viscosity

resistance of a liquid to flow, decrease with higher molar mass and increase with higher temperature

capillary action

ability of a liquid to move through a very narrow space (sometimes against gravity), reliant on cohesion and adhesion

cohesion

attractions between molecules within the liquid

adhesion

attraction between liquid molecules and surface

6 strong acids

perchloric acid (HClO4), hydrochloric acid (HCl), hydrobromic acid (HBr), hydroiodic acid (HI), nitric acid (HNO3), sulfuric acid (H2SO4)

6 strong bases

lithium hydroxide (LiOH), sodium hydroxide (NaOH), potassium hydroxide (KOH), calcium hydroxide (Ca(OH)2), strontium hydroxide (Sr(OH)2),barium hydroxide (Ba(OH)2)

aerosol

liquid dispersed in gas

solid aerosol

solid dispersed in gas

foam

gas dispersed in liquid

emulsion

liquid dispersed in liquid

sol/ gel

solid dispersed in liquid

solid foam

a gas dispersed in solid

sol

a liquid dispersed in solid

colloids

heterogeneous mixture with intermediate sized particles, stays mixed (does not settle into layers), scatters light

suspension

heterogeneous mixture with large particles visible to the naked eye, does not transmit light, settle into layers when left sitting

VSEPR theory

electron pairs in a molecule will repel one another, therefor electrons will distribute themselves in positions around the central atom that are as far away from each other as possible

polarizability

measure of ease with which electron charge density is distorted by an external electron field

-reflects the ability for which a dipole can be induced

-greater means stronger IMF

-more present in larger molecules

diagonal line

q=mcdeltaT

horizontal line (phase change)

q=ndeltaH

endothermic

absorbs heat, breaking bonds, solid to liquid to gas

exothermic

releases heat, forming bonds, gas to liquid to solid

sublimation

solid to gas

deposition

gas to solid

melting

solid to liquid

freezing

liquid to solid

boiling

liquid to gas

condensation

gas to liquid

triple point

the point on the phase diagram where all three states of matter exist and are in equilibrium

critical point

the point on the phase diagram where the liquid and gaseous states are indistinguishable

supercritical fluid

any substance at a temperature and pressure above its critical point, distinct liquid and gas phases merge into a single uniform phase

crystalline solid

particles arranged in a repeated 3 dimensional lattice, distinct melting point, ex. diamond, ice, salt, sugar

amorphous solids

particles have a random, disordered orientation, ex. glass, rubber

ionic solids

ionic bonds hold the solid in a regular 3D arrangement, high melting point, brittle, hard

molecular solids

held together by IMFs, low melting point, non conducting

covalent network

atoms held together in large networks or chains by covalent bonding, high melting point, hard, nonconducting

metallic solid

high conductivity, metal atoms held together by a sea of delocalized electrons

allotrope

some solid substances can exist in more than one form

crystal defects

imperfections in the geometric shape of atoms within a crystalline solid, caused by rapid cooling or high energy radiation striking solid

density

(MW # of atoms) / (a³ * avogadros)

R

8.314 J/molK or .0821 L*atm/molK

volume of a sphere

4/3pir³

volume of unit cell

a³ (edge length)³

why is the solvation process thermodynamically favorable

increase in entropy and decrease in energy

increasing solubility of solids

increase temperature, smaller particles, stirring/ agitation

increasing solubility of gases

decrease temperature, increase pressure

strong electrolyte

completely dissociates into ions (strong acids and strong bases as well as ionic comopunds comprised of elements from these strong acids and bases)

weak electrolyte

produce a few ionds, does not dissociate completely in solution, experience equilibirum

henry’s law

C=KP, the solubility of gas is directly proportional to its partial pressure above the liquid

miscible

two liquids which share intermolecular forces and are able to mix with one another

immiscible

two liquids that do not have intermolecular ofrces in common and will not mix with one another

molarity (M)

moles of solute/ L solution

molality (m)

moles of solute/ kg of solvent

parts per million

mg solute/ L solution (10^6)

parts per billion

ug solute/ L solution (10^9)

1 pm =

1e-10 cm

1 micrometer (ug)=

1e-4 cm

vapor pressure lowering

adding solute lowers b/c solute particles occupy space at the liquids surface, less particles are able to push through and escape

P (solvent) = X(solvent) * P initial (solvent)

delta P = X(solute) * P initial (solvent)

boiling point elevation

more solute means more energy required for solvent molecules to boil bc crowdedness

change in temperature= ikm

m is molality of solute

add to original boiling point

freezing point depression

addition of solute makes it more difficult for solvent to organize itself into structure, more energy must be withdrawn from solution to cause solidification

subtract from original freezing point

change in temp = ikm

osmotic pressure

pressure required to stop osmosis

iMRT

only applies to aqueous solutions and does not change with increasing IMFs

osmosis

flow of solvent into the solution through a semipermeable membrane

lower solute concentration to higher solute concentration

hypertonic solution

higher concentration of solute particles outside of cell, water flows outside of cell and shrinks (crenation)

hypotonic solution

solute concentration is greater inside the cell, water rushes into cell and causes hemolysis

tyndall effect

colloid particles scatter visible light

coagulation

colloid particles clump and chunks become so heavy they fall out of dispersion

-caused by heating (increased KE makes particles more likely to collide) and electrolyes

aerogel

solid foam, looks like smoke

start with liquid in solid and replace to have gas in solid without compromising solid structure, least dense solid on earth but very strong and good thermal insulator

removal of grease by soap

soap is amphiphillic, molecules surround grease with hydrophobic tails facing inward to collect grease

emulsification

stabilization of an unstable colloid, one liquid is broken into tiny droplets and dispersed throughout the other, dispersed by amphiphillic emulsifier