AP CHEM UNIT 3 REVIEW

macroscopic properties of gases

volume: amount of space occupied by the gas / amount of gas: number of moles / temp: measurement of average kinetic energy / pressure: force exerted on surfaces by molecular collisions

effect of volume on pressure

inversely proportional / volume decreases when pressure increases / less surface area = greater number of collisions

effect of moles on pressure

directly proportional / moles increase, pressure increases, number of collisions increases

effect of temperature on pressure

directly proportional / average KE of molecules increases, pressure increases / collisions occur more often and with mroe energy

partial pressures

pressure exerted by each gas alone / ideal gases behave same

Dalton’s law of partial pressures

P(total) = P1 + P2 + P3…

mole fraction (Xi)

ratio of moles of one gas to total number of moles, can use both moles and pressure

single gas particles

particles in continuous random motion / constant velocity and direction between collisions / new velocity and direction after collisions / elastic collisions (particles don’t stick)

different gas particles

lighter particles move faster, temperature is the same, temp is proportional to average KE

larger particles

travel a shorter distance between collisions, collides more often / particle size is negligible in larger containers, ideality in gases assume combined particle volume is zero

kinetic molecular theory

summarizes ideal behavior of gases / random continuous motion / perfectly elastic collisions / negligible particle volume / constant temp = constant KE

maxewell-boltzmann distributions

shows how particle speed is distributed / x-axis: particle speed / y-axis: how frequent particle speed is / area under curve is constant

comparing temp in maxwell boltzmann distribution

as temp increases, number of particles with higher speeds increases / fewer particles will be slow / curve flattens as stretches

comparing gas molecules in maxwell boltzmann distribution

gases with different masses at same temp have different average speeds / heavy gases more slow / lighter gases faster so curve stretches and flattens

real gas behavior

all gases are able to condense, attractive forces, molecules vary in size and have same volume, attractive forces means PV not = nRT

effect of intermolecular forces

as IMF increases, pressure decreases / high temp: IMF more negligible, gas behaves ideally / low temp: IMF is significant and non ideal

effects of molecular volume

with significant particle volume, number of collisions increase and actual pressure would be more than 1 atm

when are gases non ideal

low temperatures, high pressures, particles with significant IMF, particles with significant molecular size

solution

a physical combination of any matter of uniform proportions / homogenous mixture

solvation

process of dissolving a solid solute in a liquid solvent

molarity

a measure of the concentration of a solutions / M=mol/L / M1V1=M2V2

particulate models

representing interactions between components of a mixture such as solute ions and solvent particles, and concentration of components

components of a liquid cannot be separated by filtration

because differences in IMF interactions of components must be considered

chromatography

can be used to separate components of a solution due to attractive forces among the parts of mobile and stationary phases

more polar a component

less interaction with a nonpolar stationary, further travel

less polar a component

more interaction with a nonpolar stationary, less travel

ionic compounds

tend to dissolve in polar solvents because cations interact with the negative dipoles and anions interact with the positive dipoles

molecular compounds

tend to dissolve in nonpolar solvents, larger and more polarizable the electron cloud, more interactions will occur with the solvent

spectroscopy

the study of matter’s interaction with electromagnetic radiation

regions of electromagnetic spectrum

associated with molecular motion or electronic transitions

microwave radiation

transitions in molecular rotational levels

infrared radiation

transitions in molecular vibrational levels / vibrational sates require more energy than molecular rotations / higher energy per photon than microwave

ultraviolet/visible radiation

transitions in electronic energy levels

photoelectric effect

the phenomenon where electrons are emitted from a material when it is exposed to light, demonstrating the particle-like properties of light.

energy of a photon

related to the frequency of the wave through Planck’s equation (E=hv)

wavelength of a photon

related to the frequency of the radiation

red

700nm

orange

600nm

yellow

580nm

green

550nm

blue

475nm

indigo

450nm

violet

400nm

beer-lambert law

linear relationship between absorbance and concentration of a solution, amount of light absorbed is directly proportional to the concentration of the absorbing species (A=Ebc)

dipole-dipole interactions

between two polar molecules, generally maximizes attraction, strength depends on magnitude of the dipole: greater the dipole moment, greater the interaction

dipole-induced dipole

between one polar and one nonpolar molecule, temporary and relies on orientation, always attractive interaction

london dispersion forces

the weak attractions between all molecules, arising from temporary dipoles, generally stronger in larger molecules.

isomers

LDFs stronger in the structure with the most surface area for forces to act upon

hydrogen bonding

only takes place between a hydrogen covalently bonded to F, O, or N and then attracted to the negative end of a dipole formed by another F, O, or N / may occur between two different parts of the same molecule

ion-dipole interaction

dipole of water interacts with the ions of a compound and forces them to separate, stronger than hydrogen bonds

properties that increase as IMF increases

melting point, boiling point, surface tension, viscosity heat of vaporization, heat of fusion

properties that decrease as IMF increases

vapor pressure (pressure exerted by a gas at equilibrium with its liquid), volatility (ease of evaporation)

ionic solids

metal and nonmetal atoms, repeating structure of cations and anions, can conduct electricity if molten, high melting point and boiling point

molecular solids

nonmetal atoms, distinct neutral molecules, held together by IMF, poor conductors of electricity, low melting and boiling point

network covalent solids

metalloids and nonmetal atoms, held together by covalent bonds, high melting and boiling points, poor conductors of electricity, hard

metallic solids

metal atoms, positive metal ions surrounded by sea of valence electrons, great conductors of electricity, malleable, ductile, variable melting and boiling points

enthalpy of fusion

measure of the energy (kJ) needed to melt 1 mole of a substance

strength of attractive force order

molecular < ionic < metallic < network covalent

solubility in water

ionic solids most soluble, network covalent and metallic solids least soluble

solid

locked in place, vibrating

liquid

above melting point, molecules moving too fast for mutual attraction to maintain locked in place, able to slide past one another, molecular at surface may evaporate

gas

attraction between molecules not significant, moves randomly in straight lines between collisions, space between molecules is much greater