Name ________________________________________ Class _________________ Date _______________
22
OXIDATION–REDUCTION REACTIONS
PRACTICE PROBLEMS
In your notebook, solve the following problems.
SECTION 22.1 THE MEANING OF OXIDATION AND REDUCTION
Determine what is oxidized and what is reduced in each reaction. Identify the
oxidizing agent and the reducing agent.
1. 2Sr 1 O2 y 2SrO
2. 2Li 1 S y 2Li2S
3. 2Cs 1 Br2 y 2CsBr
4. 3Mg 1 N2 y Mg3N2
5. 4Fe 1 3O2 y 2Fe2O3
6. Cl2 1 2NaBr y 2NaCl 1 Br2
7. Si 1 2F2 y SiF4
8. 2Ca 1 O2 y 2CaO
9. Mg 1 2HCl y MgCl2 1 H2
10. 2Na 1 2H2O y 2NaOH 1 H2
SECTION 22.2 OXIDATION NUMBERS
1. Give the oxidation number of each kind of atom or ion.
a. Sn
c. S22
e. Se
g. Sn41
b. K1
d. Fe31
f. Mg21
h. Br2
2. Calculate the oxidation number of chromium in each of the following formulas.
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a. Cr2O3
b. H2Cr2O7
c. CrSO4
d. CrO422
3. Use the changes in oxidation number to determine which elements are oxidized
and which are reduced in these reactions. (Note: It is not necessary to use
balanced reactions.)
a. C 1 H2SO4 y CO2 1 SO2 1 H2O
b. HNO3 1 HI y NO 1 I2 1 H2O
c. KMnO4 1 HCl y MnCl2 1 Cl2 1 H2O 1 KCl
d. Sb 1 HNO3 y Sb2O5 1 NO 1 H2O
4. For each reaction in problem 3 above, identify the oxidizing agent and reducing
agent.
Review Module / Chapters 21–24
35
Name ________________________________________ Class _________________ Date _______________
SECTION 22.3 BALANCING REDOX EQUATIONS
1. Balance these equations using the oxidation-number-change method.
a. C 1 H2SO4 y CO2 1 SO2 1 H2O
b. H2S 1 HNO3 y S 1 NO 1 H2O
c. HNO3 1 HI y NO 1 I2 1 H2O
d. Sb 1 HNO3 y Sb2O5 1 NO 1 H2O
e. KMnO4 1 HCl y MnCl2 1 Cl2 1 H2O 1 KCl
f. KIO4 1 KI 1 HCl y KCl 1 I2 1 H2O
g. Zn 1 Cr2O722 1 H1 y Zn21 1 Cr31 1 H2O
2. Write half-reactions for the oxidation and reduction processes for each of the
following reactions.
a. Fe21 1 MnO42 y Fe31 1 Mn21 (acidic solution)
b. Sn21 1 IO32 y Sn41 1 I2 (acidic solution)
c. S22 1 NO32 y S 1 NO (acidic solution)
d. Mn21 1 H2O2 y MnO2 1 H2O (basic solution)
3. Balance these reactions using the half-reaction method.
a. Zn 1 HgO y ZnO222 1 Hg (basic solution)
b. Fe21 1 MnO42 y Fe31 1 Mn21 (acidic solution)
c. Sn21 1 IO32 y Sn42 1 I2 (acidic solution)
d. S22 1 NO32 y S 1 NO (acidic solution)
e. Mn21 1 H2O2 y MnO2 1 H2O (basic solution)
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f. CrO2 1 ClO2 y CrO422 1 Cl2 (basic solution)
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Review Module / Chapters 21–24