CHM 142 final exam Flashcards
rate of dissappearance
reactants
-[Concentration of reactants]/change in time
rate of appearance
products
[concentration of products]/change in time (s)
the rate of appearance of one molecule—the rate of disappearance of another molecule
equals
equation to find rates of change for a reaction
-1/a([A]/change in time)=1/b([B]/change in time)
general rate law
R= k[A]^x[B]^y
what can affect the value of k (rate constant)
temperature
when a reaction depends on a single reactant to the first order
first order reactions
integrated rate law (1st order)
ln[A]=-kt+ln[A]initial
what does a first order graph look like?
linear line
when a reaction depends on one reactant to the 2nd order or two first order reactants
second order reaction
integrated rate law (2nd order)
1/[A]=kt+1/[A]initial
what does a second order graph look like?
a curved line
integrated rate law (0th order)
[A]=-kt+[A]initial
what does a zeroth order graph look like?
Horizontal line
1st order half life
.693/K
2nd order half life
1/(K*[A]0)
rate laws relate—and—
rate and concentration
integrated rate laws relate—and —
time and concentration
the minimum E required to intiate a chemical reaction
Activation energy
the higher the value of E the — rate
slower
Arrhenius equation
k= Ae^(-Ea/RT)
determining the activation E with one rate constant
ln(k)=-Ea/RT +ln(A)
determining the activation E with two rate constants
ln(k1/k2)=-Ea/R(1/T2-1/T1)
if a reaction has a slow first step what determines the rate of the reaction?
the rate law of the slow first step
what is the equation for finding the eq. constant (K)
Keq = [D]^d*[C]^c/[A]^a[B]^b
How do you find the equilibrium constant for gases? (Kp)
= Kc(RT)^change in n
n = moles gas product= moles gas reactant R =.08206
True or false concentrations of reactants and products have to be the same during equilibrium?
false, they have to be stoichiometrically equivalent
If K»1 the reaction favors—
the products, lies to the right
If K < 1 the reaction favors—
the reactants, lies to the left
If you are perfoming Hess’s law like calculations to find Kp or Keq name some of the differences between doing it originally and doing it with eq constants
- if you need to ‘flip the sign’ dont flip the sign of the value, inverse it (1/x)
- if you multiply a reaction you put the Keq or Kp to that numer (3x = Keq^3)
- at the end you multiply the Keqs and Kps together, not add
Are pure solids and liquids included in eq constants?
no, their values are 1
Reaction Quotient (Q)
calculated like K but concentrations from any point in the reaction can used, not just at eq.
when Q»k the reaction…
shifts left
when Q«K the reaction…
shifts right
how will the reaction shift if volume is increased?
towards the side of the reaction that produces more moles
If heat is added to an exothermic reaction how will the reaction shift?
to the left, reactants
If heat is added to an endothermic reaction how will the reaction shift?
to the right, to the products
Do catalysts affect the values of Keq
no, only how fast it is reached
Buffer
a solution that contains an acid and its weak base that has resistance to pH change
Henderson Hasselbalch equation
pH=Pka + log [base]/[acid]
When choosing a buffer, choose one with a — about equal to the desired —
Pka, pH
If a strong base is titrated with a weak acid is the starting pH high or low?
High, strong base has high pH
If a strong acid is titrated with a weak base does the eq point occur just below or just above a pH of 7
below, start with a low pH
Does the presence of commmon ions increase or decrease the solubility
decrease because the ion will dissolve less than it normally would with a common ion
Do the formation of complex ions increase or decrease solubility?
Increase by forming metal ion + lewis base
Metal oxides and hydroxides that are relatively insoluble in water but are soluble in strongly acidic and strongly basic solutions are said to be—
Amphoteric
If Q>ksp the solution is —
super saturated
If Q<Ksp the solution is—
unsaturated
If Q=Ksp the solution is —
saturated
Change in Free energy equation
concerning standard gibbs free E
standard gibbs free E +RTln(Q)
Change in free energy
enthalpy and entropy
Change in H-Tchange in S
transition metal complexes
transition metal + ligand
charged = complex ion
ligands
concerning metal complexes
bonding molecule to the metal ion
- usually polar or an anion
- must have one pair of unpaired electrons
werners theory
every transition metal has a primary valence and a secondary valence
primary valence
oxidation state
secondary valence
coordination number
why do the transition metals after 6B start to increase in size
metallic bonding strength decreases as anitbonding orbitals are filled so it cancels out effective nuclear charge and size increases
Lanthanide contraction
periods 5 and 6
this is why we dont see the expected increase in radius size in the second half of the transition metals, the filling of the 4f orbitals decrease radius size
Transition metals lose their — orbitals first
S orbitals
then d orbitals
all spins are paired, weakly repulsed in a magnetic field, generally not considerd magnetic
diamagnetic
unpaired electrons where the spins are not affected by surrounding atoms, weakly attracted in a magnetic field
paramagnetic
ferromagnetism
- stronger than paramagnetism
- all spins align parallel to the magnetic field
- create permenant magnet
antiferromagnetism
- unpaired electrons align their spins opposite to adjacent atoms but the magnetic charges cancel out
ferrimagnetism
unpaired electrons have opposite spins to adjacent ones but the magnetic charge does not cancel out
happens in atoms that have diff number of electrons
ferro, ferri, and antiferrimagnetic substances become — when heated above a certain temperature
paramagnetic
thermo E cancels out magnetic forces
The metal ligand bond happens as a result of —
Lewis acid and Lewis base interaction
is the ligand the lewis acid or base?
lewis base
electron donor
is the transition metal the lewis acid or base?
lewis acid
electron acceptor
Complex formation can change—
- tendency of redution and oxidation
- color
If the coordination number if 4 what is the likely geometry?
tetrahedral or square planar
if the coordination number is 6 what is the likely geometry?
Octahedral
anions from strong bases are—
halides
neutral
cations from strong bases are—
grp I and II
neutral
anions from weak bases are—
basic
Transition metals are usually —
acidic
Spontaneous processes
Processes that proceed with no outside assistance
S is positive for spontaneous process
Nonspontaneous procsses
Processes that require outside assistance to proceed
S is negative for nonspon processes
State functions
T, H, S, E and G
not q and w
Entropy
the randomness of a system
Entropy =
S
qrev/ T
qrev= Enthalpy
2nd law of thermodynamics
the entropy of the univ increases for any spontaneous process
1st law of thermodynamics
energy can not be created or destroyed only converted
3rd law of thermodynamics
Entropy of a substance that is perfectly crystalline (1 m.s.) is 0
Entropy =
with microstates
k*ln(wfinal/winitial)
k= boltzmans constant 1.38*10^-23
Gibbs free E =
standard gibbs value
Standard G+RT*ln(Q)
gibbs free E =
enthalpy and entropy
Change in H - T*Change in S
If a reaction is spontaneous should G be negative or positive
negative = spon process for G
if G = 0 the system is at eq
Donor atom
the atom in a ligand that bonds to the metal ion
Monodentate
has one donor atom, can bind to one coordination site
H20, NH3, CN-, Cl-
Bidentate
Has two donor atoms, can bind to two donor sites
Carbonate ion, Oxalate, (en) ethylinediamine
Polydentate
More than two donor atoms, can bind to more than two donor sites
EDTA, Triphosphate ion
Prevents reactions with metal atoms by forming a ‘claw’ over them
Chelating agents
examples of porphyrins
Heme, Chlorophyll
made of porphine molecules and found in biological systems
Porphyrins
Heme
Porphyrine with Fe (II) as the metal ion
Chlorophyll
Porphyrin with Mg(II) as the metal ion
isomer
same chemical formula, different bonds and structures
Structural isomer
different connections/ bonds of atoms
linkage isomers and coordination sphere isomers
linkage isomer
the ligand is bound to the metal by different atoms
Ex: NO2 can choose to bond by N or by O
Coordination sphere isomer
differing atoms within the coordination sphere and outside of it
Stereoisomers
same bonds but different geometric arragnment
Geometric isomers and enantiomers
geometric isomers
cis/trans isomers
Bonds on different or same sides of molecule
cis= same side trans= diff side
Are geometric isomers found in all geometric arrangments?
No they are only found in octahedral or square planar, not tetrahedral
enantiomers
optical isomers
isomers that are mirror reflections of each other but cannot be superimposed on each other
rotates plane of light to the right
dextratory enantiomer
rotates the plane of light to the left
levrortory enantiomer
Does not rotate plane of light/ cancels out
racemic mixture
Electrons flow spontaneously from the — to the —
anode to the cathode
where oxidation occurs, negative value, loses mass over time
anode
where reduction occurs, positive value, gains mass over time
cathode
the more — the emf value is the more likely it is for — to occur
positive, reduction or negative, oxidation
For a reaction to be spontaneous Ecell needs to be — and G needs to be —
positive, negative
primary cell
cannot be recharged
alkaline (AA AAA)
secondary cell
can be recharged
Lead acid, Ni-Cd, Li batteries
Q=
colombs
It=nf
I = amperes t =time n= number of moles of e- f= faradays
the color of a transition metal complex depends on — and —
the identity of the ligand and identity of the metal ion
If an object is perceived as blue what is its wavelength? and what colors of light is it absorbing?
wavelength: about 450 nm
absorbed light: orange
If an object is perceived as yellow what is its wavelength? and what colors of light is it absorbing?
wavelength: 570
absorbed light: purple
Magnetic properites of complexes depend on —
the number of unpaired electrons in the d orbital
the electrostatic field of the ligands interacts with the d orbitals in the metal ion
crystal field theory
the orbitals that point towards the ligands are the — E orbitals
High
the orbitals that do not point towards ligands are the— E orbitals
Low
Ranks a ligands ability to increase crystal splitting E
Spectrochemical series
The Spectrochemical series
- Cl-
- F-
- H2O
- NH3
- en
- NO2-
- CN-
ligands on the left end/ low end of the spectrochemical series
weak field ligands
dont easily increase E (high spin)
ligands on the right/ high end of the spectrochemical series
strong field ligands
easily increase E between orbitals (low spin)
In an octahedral arrangement — is the low E orbitals
t2
6 electrons
In a octahedral arragnment — is the high E orbtials
e
4 electrons
in tetrahedrals — is the high E orbitals
t2
In tetrahedrals — is the low E orbitals
e
Almost all square planars are — spin
low spin
Almost all tetrahedrals are — spin
high spin
High spin complex
low field ligand, not a big different in E when placing electrons in orbitals
all orbitals filled then start pairing
Low spin comlex
high field ligands, big diff in E when placing electrons in orbitals
all in low and then can add to high E orbital
Alpha decay
emission of 4/2He nucleus
Beta decay
emission of a High E electron
written 0/-1 e
Gamma Decay
emits High E photons, does not change proton or neutron value
positron emission
opposite of beta decay, emitts anti electron
written 0/+1e or +Beta
electron capture
capture of an electron from the electron field by the nucleus
What kind of radiation does an element under go if it is above the belt of stability
Beta decay
increase protons, decrease neutrons
What kind of radiation does an element under go if it is below the belt of stability?
Positron emission or electron capture
increase neutrons
Radioactive decay is a — order process
first order
first order half life
t1/2= .693/k
ln(Nt/N0)=
Nt= current number of nuclei N0= initial number
-kt
Change in E=
Change in M *c^2
c= speed of light 2.9979*10^8
Change in E=
Change in M*c^2
c= speed of light 2.9979*10^8
Nuclear binding E
The amount of E it takes to separate the nucleons of an atom
separating heavy nuclei into smaller more stable molecules
Fission
our current source of nuclear E
Bringing together light/small nuclei into larger more stable ones
Fusion
better for E but no materials to withstand rxns
Fuel elements
fissonable materials
Moderator
Slow down nuclei so they can actually hit each other
control rods
absorb nuclei. to keep rxn from over heating
primary coolant
takes heat away from rxn
secondary coolant
takes heat from primary coolant away to generate E
Is ionized or non ionized radiation more harmful?
Ionized radiation is more harmful bc/ it forms free radicals
