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Chem 162 Experiment #2: Electrochemistry (Latest Complete solution)
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Chem 162 Experiment #2: Electrochemistry (Latest Complete solution)
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Name: Quiz Section: CHID Number: Lab Partner:
Note:
Chem 162 Experiment #2: Electrochemistry All sections of this
report, except the
structural formulas,
Total Points = 60 (10 notebook, 50 report) must be typed.
By signing below, you certify that you have not falsified data, that you have not plagiarized any part of this lab report, and
that all calculations and responses other than the reporting of raw data are your own independent work. Failure to sign this
declaration will result in 5 points beind deducted from your report score.
Signature:
Data and Calculations
Part I: Standard Potentials
Standard Potentials vs. Silver/Silver Chloride Reference Electrode
Cell Number Potential, V Cathode Anode
vs. Ag/AgCl Electrode Electrode
(spontaneous rxn)
1 (Ag) 0.553 Ag Ag/AgCl
2 (Zn) 0.759 Ag/AgCl Zn
3 (Pb) 0.361 Ag/AgCl Pb
4 (Cu) 0.137 Cu Ag/AgCl
8 pts
Spontaneous Reaction
(between each half cell and Ag/AgCl reference)
Cell #
1 Ag+ + Ag(s) -> Ag+ + Ag(s)
2 2Ag+ + Zn(s) -> Zn2+ + 2Ag(s)
3 2Ag+ +Pb(s) -> Pb2+ +2Ag(s)
4 Cu2+ + 2Ag(s) -> 2Ag+ + Cu(s)
Using the data from Table 2.1 in the lab manual, type the calculation for the expected E o value for the Cu2+/Cu - Ag/AgCl cell.
(3 pts)
Cu2+/Cu Eo (redox) 0.34V; Ag/AgCl Eo (ox) -0.22V
Eo cell= Eo (red) + Eo (ox)
Eo cell = 0.34V + (-0.22V)
Eo cell= 0.12V
Based on your measured potential for this cell and the literature value for the standard reduction potential for the Ag/AgCl reference
electrode, what would you expect the overall potential to be for the spontaneous reaction between your Cu 2+/Cu electrode and a standard
hydrogen eletrode? Type your calculation for the expected standard reduction potential vs the SHE as well as the % error between this value
and the literature value. (3 pts)
Literature value for the standard reducton potential for Cu 2+/Cu (redox) = 0.34V
Standard reduction potential of Cu2+/Cu (with respect to SHE) = measured potetial + E(Ag/AgCl reference)
0.137 V + 0.22 V = 0.357 V
Percent Error = %error = |actual - theoretical| * 100 = |0.357– 0.34| * 100 = 0.5%
theoretical 0.34
Zinc (#2) and Lead (#3) Ecell, V
Expected Ecell (V) based on YOUR Eo values Actual value of your measurement (V)
0.398 V 0.393 V
4 pts
Oxidation Half-reaction: Zn(s) -> Zn^2+ +2e^-
Reduction Half- reaction: Pb^2+ +2e^- -> Pb(s)
Page 1 of 3
, Type the
calculation Cell/Line notation for cell that should give exactly 0.50V Actual value of your measurement (V)
of the |Cu(s)| Cu(NO3)2(aq) .1M || Cu(NO3)2(aq) 1M| Cu(s)| 0.47 V
expected
Type the calculations used to determine how to prepare the concentration cell:
potential
based on
YOUR Eo = 0.47 E= 0.50V
measured
0.5=0.47-(0.591/2)lnQ
Eo values: 0.03=-(0.591/2)lnQ
(this is one 0.06=-0.591lnQ
calc. (-0.06/0.591)=lnQ
example) Q=10^(-0.06/0.0591)
Q=0.096
Zn: : Eo =
0.759V for
the
Cathode
(reduction)
o
Pb: : E = = -
0.361V for
the Anode
(oxidation)
Eo cell= Eo
(reduction)
+ Eo
(oxidation)
Eo cell=
0.759V +
(–0.361)=
0.398V
Page 2 of 3
Part II:
Batteries
Cell/Line Notation for battery with voltage greater than +1.7V
|Zn(s)| Zn2+ (aq) 1M || AgCl (aq) 1M | Ag(s) | ; |Pb(s) | Pb2+ (aq) 1M || Ag+ (aq) 1M| Ag(s)|
Measured Voltage:
1.666 V
Part III: Concentration Effects
Copper
Concent
ration
Cell
(half
cells #4
and #5)
Potential, V
Measured
37.4 mV
Type the
calculation
for the
expected
cell
potential:
E= Eo –
(0.0591/n)l
ogQ
E=0 –
(0.0591/2)l
og(0.1/1)
E=
0.02955V
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