LECTURE:
Electrochemistry
"The L,\.TODAY'S study of the interchange of
chemical and electrical enerry"
"Electrochemistry"
(Chapter 11)
l)
>
Reduction-Oxidation (Redox) Reactions
(rxns involving the transfer of electrons)
Galvanic Cells
-> 2 Processes
2)
Standard Reduction Potentials
3)
Standard Hydrogen Electrode
O the generation of an electric current from
chemical reaction
a
@ the use of electric current to produce
chemical change
Important applications:
.
.
.
Batteries
Corrosion prevention
Commercial electrolyticprocesses
2
Redox processes
1) Separate
For the redox reaction:
zr{A>
.
two half
reactions\-,
2) Link metals (electrodes)
+ Ct}*(aq) -+ Zr**(aq1 +
J-
Current
@-
flow)
Cri'1s)
Znmetal
Oxidation reaction:
Zn(s) half -+
Generating Gurrent
Cu Metal
Z**(aq) + 2e- (loss of electrons)
+
Increase oxidation number
.
Reduction half reaction:
Ct*(aq)+ 2e-+ Cu(s) (gainof
+
.
electrons)
Reduced oxidation number
Spontaneous reaction: Put Ztncmetalrn
CrP* solution -+ coppermetal
Zn: reducing
ZnSOu(aq) solution
CuSOo(aq) solution
-+Znz* +
-+
SO42-
(1M)
Cu2+
Oxidation occurs at
Reduction occurs at
(Zn electrode)
Anode
Cathode (Cu electrode)
Zn(s) -+ Zr*+(aq) + 2e- A**@q) + 2e- -+ Cu(s)
Electrons flow from anode
agent (reduces Cu2*)
Cu2*: oxidizing
agent (oxidizes Zn)
+ SO42- (lM)
+
But only for an instant!
Charge builds up on each side
cathode