AP Chem random things to memorize

at which conditions are gases most ideal

high temp, low pressure, no IMFs

if real pressure is greater than ideal:

size of the particle is not negligible

iI real pressure is less than ideal

due to attractive forces

boltzmann curve

higher peak/more to the left

cold

lower peak more to right

hot

2 different particles at the same temperature

same kinetic energy

heavier one will move slower, vise versa

2 same particles at same temp

KE and speed the same

2 same particles at diff temps

hotter = higher KE and speed

cooler = lower KE and speed

combustion analysis

finding empirical formula for CxHy

what can change the eq. constant

only temp

Le Chat’s increase V or decrease P

move to side with more moles

decrease V increase P

move to side with less moles

equal moles

no shift

redox titration in acicidc solutions

add H2Os to balance O’s and H+ to balance H’s

basic solutions

same as acidic and then add OH- to side H+ was added to and cancel out H2Os

water at temp > 25 Deg C

more acidic, vise versa

strong acids

HCl, HI, HBr, HClO4, HNO3, HClO3, H2SO4

strong bases

NaOH, LiOH, CsOH, RbOH, KOH, Ca(OH)2, Ba(OH)2, Sr(OH)2

WA + WB

Ka = [H3O+][A-]/[HA]

Ka = x²/[HA]

x = [H+]

-log(x)= pH

WA + SB

HA + OH- →A- + H2O

H+ donated from HA to OH

WB + SA

B + H3O+ → HB+ + H2O

H+ donated from H3O+ to B

perfect buffer

[HA] = [A-], pH = pKa

titrations

SA + SB pH = 7

WA + SB pH > 7

SA + WB pH < 7

buffers continued WB + WA

if more WA pH< pKa

if more WB pH>pka

percent ionization

[H+]/[HA]

buffer capacity

smaller concs = lower, vise versa

Henderson Hassle-Bach

pH = pKa + log [A-]/[HA]

if equal concs of A- and HA, log 1 = 0, so pH= pKa (perf buffer)

diamagnetic

no unpaired e-s, can’t be made magnetic

paramagnetic

unpaired e-s, can be made magnetic

effective nuclear charge

number of protons minus number of inner e-

ionization energy exceptions

group 2→ 3 ex. Be to B

2s orbital has a small probability of being closer to the nucleus than 2p so Be is smaller than B, breaking the trend

group 5 → 6 ex. N vs. O

IE for O is less than N because it has a greater repulsion in the p orbital

photoelectron spectra graphs, more protons:

peaks shift to the left

types of light in order from high Energy/High freq/short wavelength to low energy/low frew/long wavelength

GXUVIMR

gamma ray, x-ray, ultra vioelt, visible, infrared, microwave, radio

C (speed of light) =

wavelength * frequency

Eneergy (J) =

planck’s * frequency

X-ray light

removes core e-s

UV, visible

removes valence e-s, excites valence e-s

infrared

vibrational

microwave

polar molecules

translational and rotational energy

Rydberg formula

1/wwavelength = (1.097× 10^7)*(1/(n1)² - 1/(n2)²)

chemical reactivity

top right diagonal of periodic tbl = easy to anion

bottom left = easy to cation

noble gases: nonreactive

changes to concentrations in galvanic cells

Q = [products]/[reactants]

products = oxidated

reactants = reduced

Ecell = Ecell - RT/nF lnQ, so if lnQ is negative Ecell increases, if positive, Ecell decreases

kinetic molecular theory

1. The temperature of a gas is proportional to its kinetic energy.

2. collisions that are elastic, momentum is conserved

3. gas particles have NO IMFs.

4. size of each atom is insignificant.

K> 10³

rxn goes to completion

K < 10^-4

rxn doesn’t occur

Eq. Hess’ Law

reaction reversed

new Keq = 1/Keq

coefficients multiplied

keq^factor multiplied by

reactions added

indiv keqs multiplied

Ksp

Ksp = concs of ions in solution

bonds breaking

endothermic, vise versa

Hess’ Law for delta H

multiply coeffs by a factor, multiple delta H by same factor

if rxn is reversed, flip sign

if rxns are added, add H values

bond enthalpy

sum of bond enthalpy of reactants - sum of bond enthalpy of products

• reverse of regular enthalpy (products - reactants)

Gibbs Free Energy

= delta H - T delta S

if positive: unfavorable

if negative: favorable

favorable

exothermic (-H) and high entropy (+S)

for +H and +S, favorable at high temps

unfavorable

endothermic and low entropy

for -H and -S, favorable at low temps

delta H for melting and freezing

(-)m delta H fusion

poisitve for melting, negative for freezing

for condensing and vaporizing

(-)m delta H vaporization

positive for evaporating, negative for condensing

freezing and condensing

exothermic

melting and vaporizing

endothermic

collisions

must have enough force and correct orientation

unit for rate constant

M^-x times time^-1

x is overall order minus 1

differential rate law

conc. vs. rate

integrated rate law

conc. vs time

zero order

rate = k

linear

[A]_t-[A]₀=-kt

slope = -k

first order

rate = k[A]

rxn slows down as it proceeds bc concs of reactants decrease

ln[A]_t-ln[A]₀=-kt

slope = -k

2nd order

rate = k[A]²

less steep than 1st order

1/[A]_t-1/[A]₀=kt

slope = k

intermediate

formed in one step, used up in later step

catalyst

used in one step, reappears in later step

“rules” for rxn mechanisms

elementary steps add up to overall

unimolecular or bimolecular (must be small for probable collision)

must correlate with observed rate law

quickie method

when slow step is not first step

cross out intermidates

circle remaining reactants and use those to make rate law

products before the slow step go in the denominator

1st order half life

t_.5=.693/k

best to use bc isn’t dependent on concentration

electronegativity and acid strength

more electronegative = greater electron drawing = more polarized = H is more attracted to water

stronger the acid = easier to dissociate