Electrochemistry.notebook
August 12, 2015
Determine the oxidation number of the
bolded element:
1) P2O5
2) NaH
3) Cr2O72­
4) H2SO4
5) NaSO3
6) H2O2
7) F2
8) PO43­
Electrochemistry
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1
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2
H
He
Hydrogen
3
Li
Lithium
11
Na
Sodium
19
K
Potassium
Helium
5
4
Be
Beryllium
Ca
Calcium
38
Strontium
55
56
Cesium
87
Fr
Francium
Sr
Ba
Barium
88
Ra
Radium
Aluminium
21
Sc
Scandium
39
Y
Yttrium
57
La
Lanthanum
89
Ac
Actinium
58
Ce
22
Ti
Titanium
40
Zr
Zirconium
72
Hf
Hafnium
104
Rf
Rutherfordium
59
Pr
Cerium Praseodymium
90
Th
Thorium
91
Pa
Protactinium
23
V
Vanadium
41
Nb
Niobium
73
Ta
Tantalum
105
Db
Dubnium
60
24
25
Cr
Mn
Chromium
Manganese
42
Mo
Molybdenum
74
W
44
Ruthenium
75
76
Tc
Re
Rhenium
107
61
Iron
43
Tungsten
Seaborgium
Fe
Technetium
106
Sg
26
Ru
Os
Osmium
27
28
Ni
Cu
Cobalt
Nickel
Copper
45
Rh
Rhodium
77
Ir
Iridium
108
109
Bohrium
Hassium
Meitnerium
62
63
Bh
Hs
29
Co
46
Pd
Palladium
78
Pt
Carbon
14
64
65
Pm
Sm
Eu
Gd
Tb
Promethium
Samarium
Europium
Gadolinium
Terbium
92
93
94
Np
Pu
Uranium
Neptunium
Plutonium
96
Am Cm
Americium
Silver
79
Au
Platinum
Nd
U
Ag
Gold
Zn
Zinc
48
Cd
Cadmium
80
Hg
Mercury
31
Ga
Gallium
49
In
Tl
Nitrogen
P
Silicon
Phosphorus
33
S
Sulfur
34
As
Se
Germanium
Arsenic
Selenium
51
F
52
Cl
Chlorine
35
Bromine
53
Te
I
Tellurium
Iodine
Pb
Thallium
Lead
Bi
Bismuth
Po
Polonium
Argon
Kr
Krypton
54
Sb
Antimony
84
Ar
36
Br
Tin
83
Neon
18
Sn
82
Ne
Fluorine
17
Ge
50
10
O
Oxygen
16
Si
Indium
81
N
15
32
9
85
At
Astatine
Xe
Xenon
86
Rn
Radon
Mt
Neodymium
95
47
30
8
C
Al
Magnesium
Rubidium
Cs
Boron
13
Mg
37
Rb
B
12
20
7
6
Curium
97
66
67
98
68
69
70
Ho
Er
Tm
Yb
Holmium
Erbium
Thulium
Ytterbium
Dy
Dysprosium
99
100
101
102
1) What substance is oxidized? Reduced?
2) Which substance is the anode? Cathode?
C) Which substance is losing mass?
IV) If the acid concentration is doubled, what
happens to the cell potential, Eo? What
happens to the ΔG?
71
Lu
Lutetium
103
Bk
Cf
Es
Fm
Md
No
Lr
Berkelium
Californium
Einsteinium
Fermium
Mendelevium
Nobelium
Lawrencium
Periodic table
Mar 26­8:02 AM
Cd (s) + NiO2 (s) + 2 H2O (l) ⇒ Cd(OH)2 (s) + Ni(OH)2 (s)
• Find the substance that is oxidized and
the substance that is reduced.
• Specify their oxidation numbers.
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Electrochemistry.notebook
August 12, 2015
e-
Oxidized
Anode
Reduced
Cathode
Gains mass
Loses mass
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Mar 7­10:57 AM
Calculate the cell potential and find out how
many electrons are transferred for:
Also, will each reaction occur?
• 2 Al (s) + 3 Ni+2 (aq) à 2 Al+3 (aq) + 3 Ni (s)
• Cl2 (g) + 2 Br­ (aq) à 2 Cl­ (aq) + Br2 (l)
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Electrochemistry.notebook
August 12, 2015
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Balancing by the Half-Reaction Method in
an Acidic Solution
__MnO4 - + __C2 O4 -2 -> __Mn+2 + __CO2
Cr2 O7 2­ + Cl­ à Cr3+ + Cl2
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Mar 28­8:10 AM
… Cr2O72­ (aq) + … H 2S(g) + … H +(aq) à ... Cr3+ (aq) + … S(s) + … H2O(l)
49. When the equation above is correctly balanced and all coefficients are reduced to lowest whole­number terms, the coefficient for H+(aq) is
(A)
(B)
(C)
(D)
(E)
2
4
6
8
14
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Electrochemistry.notebook
August 12, 2015
Cu2+ (aq) + 2 e­ ⇒ Cu (s) E = 0.34 V
Cd2+ (aq) + 2 e­ ⇒ Cd (s) E = ­0.40 V
Sn2+ (aq) + 2 e­ ⇒ Sn (s) E = ­0.14 V
Cl2 (g) + 2 e­ ⇒ 2 Cl­ (aq) E = 1.36 V
A 1M solution of Cu(NO3)2 is placed in a beaker with a strip of Cu metal. A 1M solution of SnSO4 is placed in a second beaker with a strip of Sn metal. A salt bridge and a wire is connected to the metals. The reaction occurs, therefore it is favorable.
(a) Which electrode is the anode, which is the cathode?
(2) Write the overall balanced cell reaction.
(C) What is that overall standard cell potential?
(Delta) What happens to the cell potential if the 1M Cu(NO 3)2 (aq)
is replaced with 4M Cu(NO 3)2 (aq)?
Mar 26­8:11 AM
Pt2+ (aq) + 2 e­ ⇒ Pt (s) Eo = 1.20 V
Ag+ (aq) + e­ ⇒ Ag (s) Eo = 0.80 V
Ni2+ (aq) + 2 e­ ⇒ Ni (s) Eo = ­0.25 V
(Alpha) Assume that electrodes of pure Pt, Ag, and Ni are available as well as 1.00 M solutions of their salts. Identify the two metals that when used to make a galvanic cell would produce the largest voltage. Calculate that voltage.
(Bravo) Will Pt metal react when placed in 1.00 M AgNO3 (aq). Justify your answer.
A 1M solution of Cd(NO3)2 is placed in a beaker with a strip of Cd metal. In the other beaker a platinum electrode is immersed in a NaCl solution with Cl2 gas bubbled around the electrode. A salt bridge and a wire is connected to the metals. The reaction occurs immediately.
(l) Does the strip of Cd metal gain or lose mass?
(m) Write the overall balanced cell reaction.
(14) What is the cell potential generated in this galvanic cell?
(o) How many electrons were transferred?
Mar 26­8:11 AM
When silver metal is placed in aqeous thallium (I) fluoride, TlF, no reaction occurs. When the switch is closed in the galvanic cell, the voltage reading is +1.14 V.
Ag+ (aq) + e­ ⇒ Ag (s) Eo = 0.80 V
(XVI) Write the reduction half­reaction for the cell.
(XVII) Write the overall reaction that occurs in the cell.
(XVIII) Calculate the value of the standard reduction potential for the Tl+/Tl half­reaction.
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Electrochemistry.notebook
August 12, 2015
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10. If the half­cell containing 1.00 M Zn(NO3)2 (aq) is replaced with a half­cell containing 4.00 M Zn(NO3)2 (aq), what will be the effect on the cell voltage of the overall reaction?
(A) The voltage will increase.
(B) The voltage will decrease.
(C) The voltage will remain the same.
(D) More information is needed to determine a result.
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