Chemistry 12
Name:
Date:
Block:
Electrochemistry V
Notes
1. Electrolysis
2. Electrolytic Cell
Electrolysis
Electrolysis: the transformation of ______________________
energy.
chemical
electrical energy into ______________________
• Used mainly in industry to ______________________ a compound into its elements.
• The electrodes used are often inert (non-reactive) materials – just involved in electron transfer
separate
Electrochemical Cell
•
•
___________
Makeselectricity.
Electrolytic Cell
•
___________ electricity.
Takes
Transforms ________________
electricalenergy into
________________ energy.
chemical
•
___________ a voltage source.
Requires
•
Transforms ________________
chemical energy into
________________ energy.
electrical
Is
•
___________ a voltage source.
•
___________ half cells.
•
___________ cell.
•
______________________ redox reaction.
•
______________________ redox reaction.
•
2
semis
E is ________________.
o
•
nonnegative
E is ________________.
o
NO
•
Needs
___________ salt bridge
•
___________ salt bridge.
•
Diagram:
•
Diagram:
QQ
•
Oxidation half reaction is ________________
the
below
•
reduction half reaction in the SRP table.
o
•
Will use the _________________
strongest OA and
•
Will use the _________________
strongest OA and
strongest
the_________________ RA.
anode
Electrons travel from the ________________ to
the ________________.
cathode
Oxidation half reaction is ________________
above the
reduction half reaction in the SRP table.
the_________________
strongest RA.
•
4h
EH
EFFI
o
I
•
anodl
Electrons travel from the ________________ to
cathode
the ________________.
O
flipped
What Am I?
1. I have 2 half cells.
E C
10.26V
O 45V
EL
2. My oxidation half-reaction is: Ni à Ni 2+ + 2 e- and my reduction half reaction is Fe2+ + 2 e- à Fe
EC
4. I transform chemical energy into electricity
EL
EC
6. You can use the SRP table to calculate how much voltage is “takes” to operate me.
Both
3. Oxidation occurs at my anode.
30th
5. In order to flow, the electrical charge requires a complete path or circuit.
7. My Eo is +0.94V.
Electrolytic Cells
THINGS TO CONSIDER:
Ex.
Liquid Content:
Electrodes:
Molten
“melted”
Inert
“non-reactive”
Naam
Ex.
Carbon
no wat
Aqueous
“dissolved in water”
Ex.
or
Platinum
Non-inert
“reactive”
Nadeau
ae
ag
Must considerHzof
as OA or RA
Ex.
Anynetalf
must consider
OA IR'A
as
Overpotential Effect of WATER:
H2O exhibits a higher potential than its
true position on the table and therefore
needs to be re-positioned.
H2O as a REDUCING Agent
Half Reaction:
acid
H2O
c
Oz 12
Eo=
0.82
2e
CT
____________________________________________________________________________________________________________________
H2O as an OXIDIZING Agent
Half Reaction:
basic
2e
Eo=
02h20
Hz 12
0.4 IV
water is
neater than
how it appears
voltage
nowater
inert
Example 1: Identify the half-reactions occurring in an electrolytic cell with carbon electrodes in molten
MgI2 and predict the voltage required to operate this cell.
o Identify the oxidizing agent and the reducing agent.
d
OI
Mg2
Mga
o
RAZI
Write the two half-reactions and calculate the voltage required.
2 I
o
2e
Iz
2e
Mga
Draw the electrolytic cell:
V
2.372
Mg
2.91
nDTEetahiadeon
2e
Iet
0.54
117
coaxidad.tn
ZI
I
Mgk
1
2e
2.9 IV
Total
separating compound
E
Mg
Example 2: Identify the half-reactions that occur in the electrolysis of an aqueous solution of manganese
(II) bromide with platinum electrodes and predict the voltage required to operate this cell.
o Identify the oxidizing agent and the reducing agent.
Mr
Brzcae
Pt
o
inert
Write the two half-reactions and calculate the voltage required.
2 Br
Bre
2e
o
2e
Hz
E
120 H
log
E
tH
OI
RI
H2O.MN Hz0
Br2HzO
0.4
Draw the electrolytic cell:
cftheoddef.frFft
2h29
as
ag
Ion
HIT
TFf
anode
oxidation
2B
Brzt2e
Mr spectator
Example 3: Identify the half-reactions that occur in an electrolytic cell consisting of copper electrodes in an
aqueous solution of CrBr3 and predict the voltage required to operate this cell.
C 3
o Identify the oxidizing agent and the reducing agent.
Cu
0A
crest
H2O
o
RI
H2O cu Br
Write the two half-reactions and calculate the voltage required.
202
Exist
Cu
203 1 Cu
o
Cu2t
Draw the electrolytic cell:
7
2
2Cr2ttCU
E
Eo
total
0934144
0.75W
417
cos
Cu
Note
appear
twice choose
stronger RA
cu't
DEFEE Ice
125
0.75W
E total
No Wls
is
2
practice
Practice:
For the following, draw the electrolytic cell and the half-reactions occurring within it and the voltage
required to operate the cell.
1. Platinum electrodes in CaSO4(aq)
inert
t
F T
tkosfqffff.IE
cathode
Jp
Coit
E Total
042
5042
0.4N
t
0.82W
1.23W
2. Iron electrodes in NaCl (aq)
non
insert
HI
1
Cl
All'T
FEIFEF.ee
fJE
EYIHthzIF2e
sHzt2oHCFe
thot
10.45W
Cl
0.4N
E'total
Nat
10.04 V
3. Carbon electrodes in molten NiBr2
inert
I
note Voltage
dueto H2O's
Overpotential
Tnotho
µO
effect
BRIT
a
DT
nineties
2B
Eototal
Breeze
C
O 26V
1.09 v
1.35W
4. Inert electrodes in CuBr2 (aq)
g
Corpt
was
Heo
fi
IIIf
HI
i
af3r
cuztJEototal
tO 34V
Hebden Workbook: Pg. 242 #65-68
0.75W
C
l.oav