Section 20.3
Half-Reactions
Practice Test
1.
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
SC.B.1.4.2
a.
9
b.
2
c.
3
d.
6
Hint
2.
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.
2
b.
6
c.
1
d.
3
Hint
3.
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
SC.B.1.4.2
a.
2
b.
1
c.
3
d.
4
Hint
4.
Which of the following half-reactions represents oxidation?
a.
Cu
2+
+ 2e
-
→ Cu
b.
Fe
3+
+ 3e
-
→ Fe
c.
Fe → Fe
2+
+ 2e
-
d.
O
2
+ 4e
-
→ 2O
2-
Hint
5.
A balanced reaction that shows only the oxidation process is a ___________.
a.
half-reaction
b.
synthesis reaction
c.
single-replacement reaction
d.
balanced chemical equation
Hint
6.
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
SC.B.1.4.2
a.
4
b.
6
c.
2
d.
3
Hint
