Exam 3 Flashcards
Lewis acid
accepts a pair of electrons, compounds with less than an octet around the central atom can and metal ions act as lewis acids, negatively charged
Lewis base
donates a pair of electrons
coordinate bond
a covalent bond formed when one anion/molecule donates a pair of electrons to another ion/molecule
ligand
a lewis base bonded to the central metal ion of a complex ion
complex ion
ionic species consisting of a metal ion bonded to one or more lewis bases
formation constant (Kf)
an equilibrium constant describing the formation of a metal complex from a free metal ion and its ligands
Trend with acid strength and cation charge
direct
Nonamphoteric hydroxides
- Fe(OH)3
- Fe(OH)2
- Cu(OH)2
Amphoteric hydroxides
- Al(OH)3
- Pb(OH)2
- Sn(OH)2
- Be(OH)2
- Zn(OH)2
- Cd(OH)2
- Cr(OH)3
how do common ions affect solubility?
common ions decrease solubility, but don’t affect the solubility product constant
How do uncommon ions affect solubility?
the increase solubility
when can you neglect s?
when it is <0.01
Affect of pH on salt solubility
acidity increases the solubility of salts with basic anions due to shift in equilibrium reactions, weaker acids increases solubility more
Q and Ksp relationship and effects
Q>Ksp, precipitate forms
Q
reversible process formula
△S=qrev / T
Second law of thermodynamics
Irreversible: △Suniverse=△Ssurroundings+△Ssystem>0
Reversible: △Suniverse=△Ssurroundings+△Ssystem> or = 0
Standard molar entropy trends
Gases and molecules with the highest molar mass have the highest molar entropies. Entropy increases as the complexity of the molecular structure increases
Which △G values indicate spontaneity in which direction?
△G<0: spontaneous in forward direction
△G>0: spontaneous in reverse direction
△Grxn equation
△Grxn=△Gºrxn + RTln(Q)
Relationship between △G◦ and K
indirect
van’t hoff equation
ln(k1/k2)=△Hº/R(1/T2 - 1/T1)
bolts,amm equation
s=kb x ln(w)
Anode
electrode at which the oxidation half reaction takes place
Cathode
electrode at which reduction half-reaction takes place
△H and △S when a rxn is spontaneous at lower temperatures
both are negative
△H and △S when aren is spontaneous at higher temperatures
both are positive
△H and △S when a rxn is always spontaneous
negative △H and positive △S
△H and △S when a rxn is never spontaneous
positive △H and negative △S
Standard reductio potential
(Eºred), the voltage for a reduction reaction at an electrode when all solutes have activities=1 and gases=1 bar
Standard oxidation potential
(Eºox) equal in magnitude but opposite in sign to Eºred
Eºcell formulas
ºEcell=Eºred(cathode)-Eºred(anode)=Eºred(cathode)+Eºox(anode)
What do standard reduction potentials tell you about their strengths as agents?
Higher positive value=stronger oxidizing agents and lower negative value = stronger reducing agents
Spotaneity of reduction potentials
higher=more spontaneous
lower=nonspontaneous
work formula
wmax=-QEcell=△G=nFEcell
w=work in joules
Q=total charge that passes through a cell
what does emf stand for
electrical potential
nernst equation forms with and without temperature
With T: Ecell=Eºcell - RT/nF ∙ lnQ
Without T: Ecell=Eºcell - 0.0592/n ∙ logQ
primary battery
cannot be recharged
secondary battery
can be recharged
Faraday law of electrolysis
m = aM/nF= aM/nF I t
a/n= coefficients
Q=charge
I=current
t=time
Current variable and units
Variable: I
Units: A
corrosion
process in which metals react with oxidizing agents resulting in the formation of other compounds
sacrificial anode
aka cathodic protection, a metal with a lower reduction potential making iron the the cathode
ekectrolysis
process in which electrical energy causes a nonspontaneous reaction to occur. Oxidiation is at anode, reduction is at cathode, signs of electrodes are reversed, cathode is negative and anode is positive
Where do cations and anions migrate to in battery cells?
cations to cathode, anions to anode
How is the mass of each electrode affected in a battery?
Anode doesn’t always lose mass because of gases, cathode always gains mass
Sigma bonds
- end to end overlap of orbitals
- s-s, s-p, or p-p orbitals
- stronger
- one symmetrical electron cloud symmetrical to internuclear axis
Pi bonds
- lateral overlap of orbitals
- p-p orbitals only
- weak bond
- electron is not symmetrical and lies above nuclear plane
