Studied by 0 peopleintermolecular 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
more Os, more acidic
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)
Note
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