105 / 912
Chapter 2
97
Copyright © 2017 Pearson Education, Inc.
19.
p
K
eq
=
p
K
a
1
reactant acid
2
-
p
K
a
1
product acid
2
For
a
, the reactant acid is HCl and the product acid is
H
3
O
+
.
For
b
, the reactant acid is
CH
3
COOH
and the product acid is
H
3
O
+
.
For
c
, the reactant acid is
H
2
O
and the product acid is
CH
3
N
+
H
3
.
For
d
, the reactant acid is
CH
3
N
+
H
3
and the product acid is
H
3
O
+
.
a.
p
K
eq
=
-
7
-
1
-
1.7
2
=
-
5.3
K
eq
=
2.0
*
10
5
b.
p
K
eq
=
4.8
-
1
-
1.7
2
=
6.5
K
eq
=
3.2
*
10
-
7
c.
p
K
eq
=
15.7
-
1
10.7
2
=
5.0
K
eq
=
1.0
*
10
-
5
d.
p
K
eq
=
10.7
-
1
-
1.7
2
=
12.4
K
eq
=
4.0
*
10
-
13
20.
Recall that the weakest acid has the strongest conjugate base.
CH
3
>
HO
−
F
−
−
NH
2
−
>
>
21.
Again, the weakest acid has the strongest conjugate base.
CH
2
>
>
CH
3
−
CH
−
H C
2
−
HC C
22.
The species on the right is the stronger acid because its hydrogen is attached to an
sp
2
oxygen, which is
more electronegative than the
sp
3
oxygen to which the hydrogen in the protonated alcohol is attached.
23.
a. A
−
CH
2
CH
3
−
C
HC CH
+
CH
3
CH
3
+
HC
B
−
HC CH
−
C
H
2
C CH
2
+
+
H
2
C CH
HC
C
−
H
2
C CH
2
+
+
H
2
C CH
CH
2
CH
3
−
CH
3
CH
3
b.
Only
A
, because only
A
has a reactant that is a stronger acid than the acid that is formed in the product.
24.
Reaction
B
. The equilibrium constants for the three reactions are:
K
eq
(A)
=
10
35
;
K
eq
(B)
=
10
-
19
;
K
eq
(C)
=
10
-
16
.
25.
The smaller the ion, the stronger it is as a base.
F
−
Cl
−
>
Br
−
>
I
−
>
26.
a.
oxygen
b.
H
2
S
c.
CH
3
SH
The size of an atom is more important than its electronegativity in determining stability. Therefore, even
though oxygen is more electronegative than sulfur,
H
2
S
is a stronger acid than
H
2
O
and
CH
3
SH
is a stron-
ger acid than
CH
3
OH
, because the sulfur atom is larger than the oxygen atom.
Because the sulfur atom is larger, the electrons in its conjugate base are spread out over a greater volume,
which stabilizes it. The more stable the base, the stronger its conjugate acid.
27.
The stronger acid has its proton attached to the more electronegative atom (if the atoms are about the
same size) or to the larger atom (if the atoms are not the same size).
a.
HBr
b.
CH
3
CH
2
CH
2
OH
2
+
c.
CH
3
CH
2
CH
2
OH
d.
CH
3
CH
2
CH
2
SH
28.
Remember that the stronger the acid, the weaker (or more stable) its conjugate base,
a.
Because HI is the strongest acid,
I
-
is the most stable (weakest) base.
b.
Because HF is the weakest acid,
F
-
is the least stable (strongest) base.