chem final

intermolecular forces

forces between separate particles

london forces

IM forces due to temporarily induced dipoles

dipole dipole

IM forces due to permanently induced dipole

hydrogen bonding

a special very strong dipole force due to the attraction of a ‘special H’ to an ‘X atom’, includes NOF as they are more EN

viscosity

measure of flow resistance

surface tension

measure of energy needed to increase surface area

constant

how does temperature behave during a phase change

Hfus and Hvap

how do you determine Hsublimation?

melt, evaporate, sublime

endothermic processes (3)

deposit, freeze, condense

exothermic processes (3)

vapor pressure

pressure of a gas that forms above a liquid or solid

always goes up (VP)

as T goes up, VP __

goes down (VP)

as IM goes up, VP __

boiling point

temperature at which VP of a substance = external pressure

Clausius Clapeyron

equation that gives the VP/ T curve and values of Hvap and Hfus

q= h x amount

equation during a phase change (think heating/cooling curve)

critical point

temperature and pressure above which there is no distinction between liquid and gas

triple point

where all three states of matter exist simultaneously

amorphous solid

solid without a set 3D repeating pattern

crystalline solid

solid with a set 3D repeating pattern

ionic solid

solid made of ions

metallic solid

solid made of metal

covalent network solid

a covalent solid with no discrete molecules, “hard”, high melting point

molecular solid

a covalent solid, low melting point, made up of C,H, O

1/2

fraction representing a face of a square

1/4

fraction representing the edge of a square

1/8

fraction representing the corner of a square

4

how many atoms in a face centered cube

2

how many atoms in a body centered cube

1

how many atoms in a primitive cube

fcc

cubic closest packing is exactly equal to

2 per atom

how many tetrahedral holes are there

1 per atom

how many octahedral holes are there

solubility

maximum amount of solute that can dissolve in a given amount of solvent at a set temperature

saturated solution

solution that cannot dissolve more solute

unsaturated solution

can dissolve more solute

supersaturated solution

an unstable condition in which a solution has more solute dissolved than the solubility limit allows

solubility increases always

how does a rise in pressure affect gas solubility

Cgas = k x Pgas

Henry’s Law

solubility decreases always

how does a rise in temperature affect gas solubility

no effect

how does a rise in pressure affect solid/liquid solubility

usually goes up

how does a rise in temperature affect solid/liquid solubility

mol A/ mol solution

units of mole fraction

mol A/ L solution

units of M

mol A/ kg solvent

units of m

colligative properties

properties of solutions that depend only on the number of solute particles

vapor pressure lowering

as concentration of solute increases, VP goes down

Psolvent = Xsolvent x Psolvent

Raoult’s Law

boiling point elevation

as solution concentration goes up, BP goes up

freezing point depression

as solute concentration goes up, freezing point goes down

multiply number of ions by M or m value

how to determine Meff or meff?

pi = Meff x R x T

osmosis / osmolarity eq

g/ mol

units of molar mass

colloids

a dispersion of a substance in a medium such that the size of dispersed particles is 5nm- 1000 nm

tyndall effect

name of the effect that causes colloids to scatter light

solution

homogeneous, clear, molecule or ion, do not settle, cannot filter, does not scatter light

colloid

heterogeneous, clear, 5nm-1000nm, does not settle, cannot filter, scatters light

suspension

heterogeneous, >1000 nm, cloudy, can filter, settles over time

always goes up

as temperature goes up, reaction rate

usually goes up

as concentration of reactants increases, reaction rate

exponent

how do you determine the order of a reaction

sum of exponents

overall reaction order is determined by

M/ sec

units of k for a zero order rate law

1/sec

units of k for a first order rate law

1/ M (sec)

units of k for a second order rate law

A = -kt + Ao

equation for a zero order rate law

ln A = - kt + ln Ao

equation for a first order rate law

1/A = kt + 1/ Ao

equation for a second order rate law

because M is not in the units of k

why can you use proportional values in a first order rate law

half life

length of time required for only 1/2 amount to remain (first order!)

kt1/2 = ln 2

half life equation used in first order rates

collision theory

states that rate is proportional to rate of collisions, reactants must hit in proper directions, and particles must hit with enough energy to convert products

lower Ea

why are exothermic reactions faster than endothermic ones

ln (k2/ k1) = -Ea/ R (1/T2 - 1/T1)

Arrhenius equation (R= 8.314 J/mol k )

the slowest step

what is the rate determining step

catalyst

a substance added to a reaction that is not a reactant or product, alters the mechanism for a lower Ea, present at start of mechanism and reforms at end

intermediate

an unstable molecule that formed early and is used later

H+ donator

bronsted lowry acid

H+ receiver

bronstead lowry base

amphoteric

a substance that can either be an acid or base depending on partner (Ex. H2O)

pKw (14)

pH + pOH =

\-log OH-

pOH=

\-log H+

pH=

Kw

\[H+\] x \[OH-\] =

1\.0 x 10^-14

the value of Kw is

digits to the right of the decimal

how do sig figs work for logs in pH/pOH values

stronger

what does a large ka tell you about a weak acid or base

Kw

Ka x Kb =

the weaker the conjugate base

the stronger the conjugate acid,

pKw

pKa + pKb =

\-log Ka

pKa =

smaller

more acidic, larger Ka, ____ pKA

HX

binary acid

horizontal: more acidic is more EN

vertical: more acidic is larger

trend for determining binary acid strength

HXO

oxoacids

1. more Os, more acidic
2. more EN X, more acidic

trend for determining oxoacid strength

Ka1 > Ka2

polyprotic acid series

buffer

solution that resists pH change, a mixture of a weak acid and its conjugate base (or a reaction that an result in such mixture)

pH = pKa

when \[HA\] = \[A-\], then

Henderson Hasselbach (buffers)

pH = pKa + log (weak base conc)/ (weak acid conc)