Section 20.3
Half-Reactions
Practice Test
1.
A balanced reaction that shows only the oxidation process is a ___________.
a.
balanced chemical equation
b.
single-replacement reaction
c.
half-reaction
d.
synthesis reaction
Hint
2.
Balance the following equation. How many electrons must be transferred between the reducing agent and the oxidizing agent in this reaction?
H
2
S + HNO
3
→ S + NO + H
2
0
a.
2
b.
3
c.
4
d.
6
Hint
3.
What is the net change in oxidation number of iodine in the following ionic reaction?
2MnO
4
-
+ I
-
+ H
2
O → 2MnO
2
+ IO
3
-
+ 2OH
-
a.
1
b.
2
c.
3
d.
6
Hint
4.
Which of the following half-reactions represents oxidation?
a.
O
2
+ 4e
-
→ 2O
2-
b.
Fe
3+
+ 3e
-
→ Fe
c.
Fe → Fe
2+
+ 2e
-
d.
Cu
2+
+ 2e
-
→ Cu
Hint
5.
Complete and balance the following chemical reaction with the smallest set of coefficients. What is the coefficient for iodine in this reaction?
HI + HNO
3
→ I
2
+ NO + H
2
O
a.
1
b.
2
c.
3
d.
4
Hint
6.
Balance the following equation with the smallest whole—number coefficients. How many moles of zinc will react with 6 moles of cobalt(III) chloride?
Zn(s) + CoCl
3
(aq) → ZnCl
2
(aq) + Co(s)
a.
2
b.
3
c.
6
d.
9
Hint
