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 Dr. Matt Law Chemistry 1C Worksheet 6
Redox Reactions
1. Identify the oxidation numbers of all of the atoms in each of the following compounds:
NH3, CrO42-, K3PO4, Mg3N2, C2H5OH, CH3CN
2. Arrange the following compounds in order of increasing oxidation state for carbon:
CO, CO2, H2CO, CH3OH, CH4
3. In the reaction of zinc metal with aqueous sulfuric acid to produce zinc sulfate and
hydrogen gas, which element is oxidized and which element is reduced? Explain.
4. Balance the following reaction equations, identify the oxidizing and reducing agents,
the number of electrons transferred, and the substances that are oxidized and reduced.
a. HCl (aq) + Cu (s) + HNO3 (aq)  CuCl2 (aq) + NO (g) + H2O (l)
b. HCl (aq) + HClO4 (aq) + FeCl2 (aq)  H2O (l) + FeCl3 (aq)
c. CoSO4 + KI + KIO3 + H2O  Co(OH)2 + K2SO4 + I2
5. Balance the following reaction equations, identify the oxidizing and reducing agents,
the number of electrons transferred, and the substances that are oxidized and reduced.
a. Cr (s) + CrO42- (aq)  Cr(OH)3 (s) in basic aqueous solution
b. MnO4- (aq) + S2- (aq)  MnS (s) + S (s) in acidic aqueous solution
c. CN- (aq) + MnO4- (aq)  CNO- (aq) + MnO2 (s) in basic aqueous solution
d. Cl2 (g)  Cl- (aq) + OCl- (aq) in acidic aqueous solution
Dr. Matt Law 6. Which of the following isn’t an example of an oxidation-reduction reaction?
(a) P4 (s) + 5 O2 (g)  P4O10 (s)
(b) 2 PH3 (g) + 4 O2 (g)  H3PO4 (s)
(c) Ca3P2 (s) + 6 H2O (l)  3 Ca2+ (aq) + 6 OH– (aq) + 2 PH3 (g)
(d) 6 Ca (s) + P4 (s)  2 Ca3P2 (s)
7. Use a table of standard reduction potentials to determine which of the following is the
strongest reducing agent: Co, Ca2+, Co3+, Cr, Au
8. Use the following half reactions and accompanying standard reduction potentials to
determine the best reducing agent. Is it Ga3+, Be2+, Be, Pd2+, or Pd?
Ga3+ + 3e  Ga
Be2+ + 2e  Be
Pd2+ + 2e  Pd
ERed
0.560 V
1.70 V
+0.987 V
9. Consider the following standard reduction potentials:
Mg2+ + 2 e–
Cr2+ + 2 e–
2 H+ + 2 e–
Pd2+ + 2 e–
Ce4+ + e–
Mg
Cr
H2
Pd
Ce3+
E = -2.37 V
E = -0.91 V
E = 0.00 V
E = 0.987 V
E = 1.61 V
(a) Which of Ce4+, Ce3+, H+, Cr2+, or Mg is the strongest reducing agent?
(b) Which of the following reagents should react with H+ to produce H2?
(a) both Mg2+ and Cr2+
(b) both Pd and Cr2+
(c) only Pd2+
(d) both Mg and Cr
(e) Mg, Cr, and Pd
10. Is Fe3+ capable of oxidizing Br-? Why or why not?
11. Which of the following would be the best oxidizing agent? Explain why.
Cl2, Na+, Fe, F-, Na
Standard Electrode Potentials
Half-reaction
Li+(aq) + e− → Li(s)
K+(aq) + e− → K(s)
Ba2+(aq) + 2e− → Ba(s)
Sr2+(aq) + 2e− → Sr(s)
Ca2+(aq) + 2e− → Ca(s)
Na+(aq) + e− → Na(s)
Mg2+(aq) + 2e− → Mg(s)
Be2+(aq) + 2e− → Be(s)
Al3+(aq) + 3e− → Al(s)
Mn2+(aq) + 2e− → Mn(s)
2 H2O(l) + 2e– → H2(g) + 2 OH–(aq)
Zn2+(aq) + 2e− → Zn(s)
Cr3+(aq) + 3e− → Cr(s)
Fe2+(aq) + 2e− → Fe(s)
Cr3+(aq) + e− → Cr2+(aq)
Cd2+(aq) + 2e− → Cd(s)
PbSO4(s) + 2e– → Pb(s) +SO42-(aq)
Co2+(aq) + 2e → Co(s)
Ni2+(aq) + 2e− → Ni(s)
As(s) + 3H+ + 3e− → AsH3(g)
Sn2+(aq) + 2e− → Sn(s)
Pb2+(aq) + 2e− → Pb(s)
2H+(aq) + 2e− → H2(g)
Sn4+(aq) + 2e− → Sn2+(aq)
Cu2+(aq) + e− → Cu+(aq)
SO42−(aq) + 4H+ + 2e− → 2H2O(l) +
SO2(aq)
Cu2+(aq) + 2e− → Cu(s)
O2(g) + 2H2O(l) + 4e– → 4OH–(aq)
Cu+(aq) + e− → Cu(s)
I2(s) + 2e− → 2I−(aq)
I3−(aq) + 2e− → 3I−(aq)
MnO4–(aq) + 2H2O(l) + 3e– → MnO2(s)
+ 4 OH–(aq)
O2(g) + 2H+ + 2e− → H2O2(aq)
Fe3+(aq) + e− → Fe2+(aq)
Hg22+(aq) + 2e− → 2Hg(l)
Ag+(aq) + e− → Ag(s)
NO3–(aq) + 2H+(aq) +e– → NO2(g) +
H2O(l)
Hg2+(aq) + 2e− → Hg(l)
MnO2(s) + 4H+ + e− → Mn3+(aq) + 2H2O
Br2(l) + 2e− → 2Br−(aq)
ClO4−(aq) + 2H+ + 2e− → ClO3−(aq) +
H2O
Eo
(V)
−3.05
−2.93
−2.91
−2.89
−2.76
−2.71
−2.38
−1.85
−1.68
−1.18
−0.83
−0.76
−0.74
−0.44
−0.42
−0.40
−0.36
−0.28
−0.25
−0.23
−0.13
−0.13
0.00
+0.15
+0.16
+0.17
+0.34
+0.40
+0.52
+0.54
+0.54
+0.59
+0.70
+0.77
+0.80
+0.80
+0.80
+0.85
+0.95
+1.07
+1.20
O2(g) + 4H+ + 4e− → 2H2O
MnO2(s) + 4H+ + 2e− → Mn2+(aq) +
2H2O
Cl2(g) + 2e− → 2Cl−(aq)
Cr2O72−(aq) + 14H+ + 6e− → 2Cr3+(aq) +
7H2O
2BrO3− + 12H+ + 10e− → Br2(l) + 6H2O
2ClO3− + 12H+ + 10e− → Cl2(g) + 6H2O
MnO4−(aq) + 8H+ + 5e− → Mn2+(aq) +
4H2O
Au3+(aq) + 3e− → Au(s)
Pb4+(aq) + 2e− → Pb2+(aq)
MnO4−(aq) + 4H+ + 3e− → MnO2(s) +
2H2O
H2O2(aq) + 2H+ + 2e− → 2H2O
Co3+(aq) + e− → Co2+(aq)
F2(g) + 2e− → 2F−(aq)
+1.23
+1.23
+1.36
+1.36
+1.48
+1.49
+1.51
+1.52
+1.69
+1.70
+1.76
+1.92
+2.87