4. What is the pH of a solution prepared from 0.250 mol of NH
3
dissolved in sufficient
water to make 1.00 L of solution? (
K
b
= 1.8 x 10
-5
)
a.
2.12
b.
2.67
c.
8.92
d.
11.33
e.
13.40
5. Which of the following reactions illustrate Al(OH)
3
acting as a Lewis acid?
a.
Al(OH)
3
→
Al
3+
+ 3OH
-
b.
Al(OH)
3
+ OH
-
→
Al(OH)
2
O
-
+ H
2
O
c.
Al(OH)
3
+ OH
-
→
Al(OH)
4
-
d.
Al(OH)
3
+ 3H
+
→
Al
3+
+ 3H
2
O
e.
Al
3+
+ 3OH
-
→
Al(OH)
3
6. Which of the following pairs of species is
not
a conjugate acid-base pair?
a. HCl and H
+
b. HSO
4
-
and SO
4
2-
c. H
2
SO
4
and HSO
4
-
d. H
2
O and OH
-
e. NH
3
and NH
2
-
7. Consider each of the following pairs of acids. Which statement is correct?
a. HClO
2
is a stronger acid than HClO
4
.
b. H
2
SO
4
is a stronger acid than H
2
SeO
4
.
c. H
2
O is a stronger acid than HF.
d. H
2
S is a stronger acid than H
2
Se.
e. HS
-
is a stronger acid than H
2
S.
8. Consider the reaction
CH
3
NH
2
+ H
2
O
→
CH
3
NH
3
+
+ OH
-
where CH
3
NH
2
is methylamine and CH
3
NH
3
+
is the methylammonium ion. Select the
correct description of this reaction in terms of Lewis acid-base theory.
a. Methylamine serves as a Lewis acid in the forward reaction and
methylammonium ion serves as a Lewis base in the reverse reaction.
b. Water serves as a Lewis base in the forward reaction and the hydroxide ion serves
as a Lewis base in the reverse reaction.
c. Methylamine serves as a Lewis base in the forward reaction and hydroxide ion
serves as a Lewis acid in the reverse reaction.
d. Water serves as a Lewis acid in the forward reaction and methylammonium ion
serves as a Lewis base in the reverse reaction.
e. Methylamine serves as a Lewis base in the forward reaction and hydroxide ion
serves as a Lewis base in the reverse reaction.