mcat chemistry chapter 11 oxid reduct electr

Start Studying!

Terms

undefined, object

copy deck

electrochem is the study of relat betw chemical react and ?: electrical energy
oxidation is ______ of an electr: loss
reduction is ________ of a electron: gain
oxidat always occur with a?: reduct
oxidizing agen causes?: another atom in a redox react to undergo oxidat and is itself reduced
OIL RIG is a way to remember that?: oxidation is loss, Reduction is gain
why do we use oxidation numbers?: to keep track of how many electr are gained or lost in a react
oxidation of free elements is?: 0
N2 , N has an oxidat number of?: 0
He has an oxidat number of?: 0
oxidation number for a monoatomic number is equal to?: the charge of the ion
Na+ has an ox n of?: +1
oxidation number of each group IA element in a compound is?: +1
oxidation of each gr IIA element in a compound is?: +2
oxidation number of group VIIA element in a compound is?: -1 except when combined with an element of higher electroneg
HCl. ox number of Cl is?: -1
HOCl, oxidat numb of Cl is?: +1
NaH, ox n of H is?: -1
CaH2, oxidat number of H?: -1
the ox n of H is _______ in comp with less electr elements than Hydrogen: -1
the more common ox n of H is?: +1
in most compd the oxidat number of O is?: -2
OF2, oxid number of O is?: +2. bec F is more electroneg than O
in peroxides like BaO2, the oxidat number of O is?: -1
sum of the oxidat numbers in all the atoms present in a neutral comp is?: zero
sum of the oxidat number of the atoms pres in a polyatomic ion is equal to?: the charge of the ion
SO42-, the sum of the oxidat numbers must be?: -2
SnCl2 + PbCl4 --> SnCl4 + PbCl2 which react is oxidized?: Sn. it goes from +2 to +4
most common method for balanc redox equat is the?: half react method. also called the ion electron method
half reaction method is?: used to balance the redox react. equat is seperated into 2 half react. oxidat part and the reduct part
Mn04- + I- ---> I2 + Mn2+ what are the 2 half reactions?: I- --> I2
Mn04- ---> Mn2+
what are the steps for balancing an oxidat reduct reaction?: 1. seperate the 2 half react
2. balance the atoms in each half react.
3.
when you are balanc the atoms in oxid reduct what atoms do you leave till last?: H and O
oxid reduct in an acidic solut, add ________ to balance the O atoms and then add _____ to bal the H atoms: H2O,
H+
oxid reduct in a basic solut add _________ to balance the O's and H's: OH-, and H20
MnO4- ---> Mn2+ balance the half reaction: Mn04- --> Mn2+ + 4H20
Mn04- + 8 H+ --> Mn2+ + 4H20
balane the charges in each half reaction: 2I- ---> I2+ 2e-
5 e- + 8 H+ + Mn04- --> Mn2+ + 4 H20
2I- ---> I2+ 2e- 5 e- + 8 H+ + Mn04- --> Mn2+ + 4 H20 after you bal the charges in each half react what do you need to do?: make sure both half react have the same numb of electr so they will cancel.
2I- ---> I2+ 2e- 5 e- + 8 H+ + Mn04- --> Mn2+ + 4 H20 what do you do next?: 5(2I- --> I2 + 2e-)
2(5e- + 8H+ + Mn04- --> Mn2+ + 4 H20)
5(2I- --> I2 + 2e-) 2(5e- + 8H+ + Mn04- --> Mn2+ + 4 H20) what do you do next?: add the half reactions

10 I- --> 5I2 + 10 e-
16 H+ + 2 Mn04- 10 e- --> 2 Mn2+ + 8 H20
10 I- --> 5I2 + 10 e- 16 H+ + 2 Mn04- 10 e- --> 2 Mn2+ + 8 H20 what will you do to get the final equation?: cancel out the electrons and
any H20s, H+s, or OH-s that appear on both sides of the
equation.

10 I- + 16 H+ + 2 Mn04 ---> 5 I2 + 2 Mn2+ + 8 H20
AN OX and a RED CAT stands for?: anode is oxidation
cathode is where reduction occurs
what are the 2 types of electrchem cells?: 1. galvanic c or voltaic c
2. electrolytic cells
spontan react occur in _______ cells?: galvanic or voltaic cells
galvanic cells are also called?: voltaic cells
nonspon react occur in ?: electrolytic cells
galvanic and electro cells have?: electrodes
redox in a galvanic cell has a _______ change in G: NEGATIVE
galvanic cells ________ energy: supply
galvanic cells oxid and reduct react are put in seperate?: half cells
batteries are galvanic or electrolytic cells?: galvanic
daniell c is an example of?: a galvanic c
daniell c zinc bar is put in a?: ZnSO4 solution
danielle c copper bar is put in ?: CuSO4 solution
danielle cell anode is?: zinc bar where Zn is oxidized
daniell cell cathode is?: the copper bar. site of reduction of Cu2+ to Cu
daniell c what happens at the cathode?: Cu2+ is reduced to Cu
daniell cell what would happen if the 2 half c were not seperated?: the Cu2+ ions would react directly with the zinc bar and no useful electr work would be done
daniell c why do you need a salt bridge and a wire to connect the half reactions?: bec otherwise an excess negat ch would build up in solut sorrounding the cathode, and exc posit ch in solut sorrounding the anode
daniell c salt bridge does what?: permits the exch of cations and anions
daniell cell the salt bridge usually has?: an inert electrolyte like KCl or NH4NO3.
these ions wont react with the electrodes or with the ions in solution
daniell cell the cations of the salt bridge flow into the ____________ to bal out the charge of __________: CuSO4 solution
SO42- ions left in solution when the Cu2+ ions deposit as copper metal
daniell cell electrons flow from _______, toward the ____________: anode,
cathode
daniell cell electrons flow from the zince bar, which is the ________.: anode
daniell cell what does the flow of electrons do to the cell?: it depletes the salt bridge and uses up the Cu2+
cell diagram what are the rules for writing it?: 1. react and prod are listed from left to right
anode I anode solut II cathode sol I cathode
2. single vertical line repres a phase boundary
3. double vertical line repres the salt bridge or
cell diagram how are the reactants and products written?: anode I anode solution II cathode sol I cathode
cell diagram single vertical line is a?: phase boundary
cell diagram double vertical line is?: presence of a salt bridge or some other barrier
electrolytic c has a ________ G: positive
electrolytic cell is spontan or nonspont?: nonspontaneous
electrolysis the half reactions are placed?: in the same container
what happens at the anode?: Zn is oxid to Zn2+
electrolytic c michael faraday theory the amount of chem change is directly proportional to?: number of moles of electr that are exch during a redox react
electr c number of moles exch can be determ from?: balanced half reaction
M n+ + ne- --> M (s)
M n+ + ne- --> M (s) one mole of M will be prod in an electr c if ________ moles of electr are supplied: n
electr cell How do you calculate the charge of a mole of electrons?: (1.6 X 10-19 C)( 6.022 X 1023 mole-1e-1)= 96487 C/mol e-
electr cell what is the charge of a mole of electrons?: 96,487 C/mol e-
faradays constant is?: 1 F=96,487 C or J/V
t or f 1 f=96,487 c: t
reminder from physics J=?: J=VC
in an electrolytic cell the anode is __________ and the cathode is __________: anode is positive
cathode is negative
in a galvanic cell, the __________ is negative and the cathode is __________: anode is negative,
cathode is positive
in an electrolytic cell reduction occurs at the _______ and the __________ is posit and the _______ is negat: reduct occurs at cathode
anode is positiv
cath is negative
galvanic cell _________ occurs at cathode ____ is neg _____ is positv: galv cell
reduct occurs at cathode
anode is negat
cath is positiv
electrolytic cell molten NaCl is electrolyzed to form?: Cl2(g) and Na (l)
what occurs at the anode?: oxidation
Na+ migrates toward the?: cathode
where does the liquid sodium end up?: it floats at the top and can be removed
Cl- ions migrate towards the?: anode. there they are oxid to Cl2
anode of an electr cell is considered to be ?: positive
why is the anode of an electrolytic cell considered pos?: its attach to posit pole of battery and attracts anions from the solut
in an electrolyt cell Is it the anode or the cathode that attracts anions from the solution?: anode
why is the anode of the galvanic cell considered negative?: bec the spont oxidat react that occurs there is the source of the cells negative charge.
oxidation occurs at the _____ in galvanic and electrolytic cells: anode
CAThode atrracts the CATions so in a daniel cell, in the copper half cell, what moves towards the cathode?: the copper II cations
CAThode attracts the CATions in a daniel cell, in the __________ half cell, the copper II cations move towards the cathode: copper
CAThode attracts the CATions in electrophoresis, the ____________ charged Amino acids will migrate toward the cathode: positively charged
CAThode attracts the CATions electrophoresis negativ ch AA will move towards the?: anode
electrophoresis _________ move towar cathode _________ move toward the anode: positiv ch aa - cathode
negat ch aa- anode
sometimes when electrolysis is done in aq solut, __________ and not the solute might be oxid or reduc: water
in aq NaCl. if it is electrolyzed, H2O migth be reduced at the cathode to prod?: H2 gas and OH- ions
aq NaCl water be reduced to H2 and OH- instead of?: Na+ being reduced to Na (s)
What can you use to determine the species in a reaction that will be oxidized or reduced?: reduction potential
reduction potential is?: tendency of a species to acquire electrons and be reduced
reduction potential the more positive the potential the greater?: the species tendency to be reduced
reduct pot the more ____________, the greater ___________: more posit the potent,
greater tend to be reduced
reduct potential ___________ the reduct potent, ____________ tendency to be reduced: more posit the reduct potent,
greater the tendency to be reduced
reduct potential what is the mnemonic?: A positive potential means more likely to succeed.
a reduct potent is measured in?: volts (V)
a reduct pot is defined relative to?: a standard hydrogen electrode
(SHE)
SHE is?: standard hydrogen electrode
SHE has a potent of?: 0.00 volts
Standard reduction potential Eo is measured under?: standard condit
what are standard conditions?: 25 C
1 M conc for each particip ion, part press of 1 ATM for each gas and metals in pure state
higer Eo mean?: greater tendenc for reduct to occur
lower Eo means?: a greater tend for oxidat to occur
a ___________ Eo means a greater tend for reduct to occur: higher
Ag+ + e -> Ag (s) E° = +0.80 V Tl+ + e- -> Tl(s) E°= -0.34 V which species will be oxid and which will be reduced?: Ag+ will be red to Ag cause it has the higher Eo
to get the oxidat potential of a given half reaction you have to?: 1.the reduct half react has to be reversed.
2. sign of reduct potent has to be reversed
standard electromotive force is?: EMF.
the differ in potential betw the 2 half cells
how do you figure out the EMF?: add the stand reduct pot of the reduc species and the stand oxidat potent of the oxidized species
t or f when adding stand potent do not multiply by the number of moles oxid or reduc: t
EMF= Eo red + ?: EMF= Eo red + Eo ox
a galvanic cell has a ___________ EMF: positive
an electrolytic cell has a ____________ EMF: negative
standard reduction potentials for Sm3+ and [RhCI6]3- are -2.41 V and +0.44 V respectively, EMF of reaction: Sm3- + Rh + 6 Cl- -> [RhCI6]3- + Sm who is getting reduced?: Sm3+ is getting reduced
standard reduction potentials for Sm3+ and [RhCI6]3- are -2.41 V and +0.44 V respectively, EMF of reaction: Sm3- + Rh + 6 Cl- -> [RhCI6]3- + Sm who is getting oxidized?: Rh is oxidized to Rh3+
standard reduction potentials for Sm3+ and [RhCI6]3- are -2.41 V and +0.44 V respectively, EMF of reaction: Sm3- + Rh + 6 Cl- -> [RhCI6]3- + Sm whats the EMF?: -2.41 V + -.44 V
=-2.85
standard reduction potentials for Sm3+ and [RhCI6]3- are -2.41 V and +0.44 V respectively, EMF of reaction: Sm3- + Rh + 6 Cl- -> [RhCI6]3- + Sm if EMF is - 2.85, what kind of cell is this?: electrolytic
standard reduction potentials for Sm3+ and [RhCI6]3- are -2.41 V and +0.44 V respectively, EMF of reaction: Sm3- + Rh + 6 Cl- -> [RhCI6]3- + Sm if EMF is -2.85. in which direct will the react be spontaneous?: to the left
a positive ch in G or Gibbs free energy is spont or non spont?: it is not spontant
a ch in G that is negat is spont or non spont?: spont
How do you determ the spontaneity of a reaction?: use ch in G
the maximum amount of useful work produced by a chemical reaction is: ch in G
or Gibbs free energy
electrochem cell the work done is dependent on?: number of coulombs and the energy available
electrochem cell ch in G=: ch G= -nFEcell
-nFEcell=?: ch in G
âˆ†G= -nFEcell what is F: faraday's constant
âˆ†G= -nFEcell in terms of units, what do you have to watch out for?: that F and G are both expressed in J. You cant have one in J and the other in KJ
âˆ†Go= -nFEocell this means that the react?: took place under standard conditions
âˆ†G= -nFEcell âˆ†G is negative only if?: EMF is positive
âˆ†G is ________, when __________ is positive: negative,
EMF is positive

Start Studying!

Deck Info

Number of cards 143