Redox Worksheet
Assign oxidation numbers to all of the elements in each of the compounds or ions below.
1. HCl
11. KMnO4
21. Ag
2. KNO3
12. LiH
22. CuCl2
3. OH-
13. MnO2
23. H2
4. KClO3
14. OF2
24. Ca(MnO4)2
5. Al(NO3)3
15. SO3
25. SiBr4
6. PbO2
16. NH3
26. HClO4
7. NaHSO4
17. N2O
27. Cr2O72-
8. H2SO3
18. H2S
28. Al(HCO3)3
9. H2SO4
19. FeSO4
29. (NH4)3PO4
10. Ba(OH)2
20. Ca3(PO4)2
30. K2H3IO6
In the following questions, give the oxidation number of the indicated atoms/ions.
1. C in CO
9. Fe in FeCl3
17. Cl-
2. Na in NaCl
10. N in NO3-
18. O2
3. H in H2O
11. Cu2+
19. I2
4. Ba in BaCl2
12. Zn2+
20. Na in Na2S
5. N in NO2-
13. C in CH4
21. S in H2S
6. S in Al2S3
14. Cl2
22. Ca2+
7. S in HSO4-
15. S in SO32-
23. C in CN-
8. Ag in AgNO3
16. Mg2+
24. P in P4O10
For following reactions write half-reactions (identify them as oxidation and reduction) and balance equations.
Identify oxidizing and reducing agents in each reaction.
1. H2 + O2  H2O
2. Fe + ZnCl2  FeCl3 + Zn
3. Al + Fe(NO3)2  Al(NO3)3 + Fe
4. Cu + AgNO3  Cu(NO3)2 + Ag
5. Al + Br2  AlBr3
6. Al + Fe2O3  Al2O3 + Fe
7. CuO + H2  Cu + H2O
8. CoCl2  Co + Cl2
9. Na + FeCl2  NaCl + Fe
10. PbS + O2  SO2 + PbO
11. Cu + HNO3  CuNO3 + H2
12. AgNO3 + Cu  CuNO3 + Ag
Electrochemistry Practice Questions
1. State the oxidation number of each element that is underlined.
a) NH3
b) H2SO4
c) ZnSO3
d) Al(OH)3
e) Na
f) Cl2
g) AgNO3
h) ClO4-
i) SO2
j) K2Cr2O4
k) Ca(ClO3)2
l) K2Cr2O7
m) HPO32-
n) HClO
o) MnO2
p) KClO3
q) PbO2
r) PbSO4
s) K2SO4
t) NH4+
2. What is the oxidation number of carbon in each of the following substances?
a) CO
b) C
c) CO2 d) CO32-
e) C2H6
f) CH3OH
3. For each of the following reactants, identify: the oxidizing agent, the reducing agent, the substance
oxidized and the substance reduced. Use oxidation numbers.
a)
Cu2+(aq) + Zn(s)  Cu(s) + Zn2+
b)
Cl2(g) + 2Na(s)  2Na+(aq) + 2Cl-
4. Write the oxidation and reduction half reactions for each redox reaction below. Then calculate the
cell potential for a cell in which these reactions occur.
a) Fe2+(aq) + Co(s) ↔Co2+(aq) + Fe(s)
b) 2Ag+(aq) + Ni(s) ↔ Ni2+(aq) + 2Ag(s)
c) Cu+(aq) + Pb(s) ↔ Pb2+(aq) + Cu(s)
5. Determine whether each reaction is spontaneous or non-spontaneous.
a) Cl2(g) + F-(aq) ↔ F2(g) + 2Cl-(aq)
b) Cu2+(aq) + 2Br-(aq) ↔ Cu(s) + Br2(g)
c) Pb2+(aq) + Fe2+(aq) ↔ Fe3+(aq) + Pb(s)
6. Oxidation is when electrons are
.
7. Reduction is when electrons are
.
8. The reducing agent undergoes
.
9. The oxidizing agent undergoes
.
10. A negative voltage means the reaction is
.