Chemistry, The Central Science, 10th edition

1
Chapter 17Additional Aspects of Aqueous
Equilibria

• Chemistry, The Central Science, 10th edition
• Theodore L. Brown H. Eugene LeMay, Jr.
• and Bruce E. Bursten

Troy Wood University of Buffalo Buffalo, NY ?
2006, Prentice Hall
2

• What is H of a 0.050 M HF solution dissolved
  in 0.20 M NaF? Ka (HF) 6.8 ? 10?4.

1. 1.7 ? 10?4 M
2. 3.4 ? 10?4 M
3. 6.8 ? 10?4 M

1. 1.4 ? 10?3 M
2. 2.7 ? 10?3 M

3
Correct Answer

1. 1.7 ? 10?4 M
2. 3.4 ? 10?4 M
3. 6.8 ? 10?4 M

1. 1.4 ? 10?3 M
2. 2.7 ? 10?3 M

The solution to problem is on the following
slide.
4
Correct Answer
HF H F?
Initial 0.050 0 0.20
Change -x x x
Eq. 0.050 - x x 0.20 x
-
?
4
)(0.050)
10
(6.8
HF
K



a

H
-
(0.20)

F

-
?

4
10
1.7

H
5

• Calculate the pH of a 0.50 M solution of sodium
  acetate in 0.050 M acetic acid (HOAc).
• pKa (HOAc) 4.74.

1. 3.74
2. 4.24
3. 4.74

1. 5.24
2. 5.74

6
Correct Answer

1. 3.74
2. 4.24
3. 4.74

1. 5.24
2. 5.74

base


log
p
pH
K
a
acid
0.50


log
4.74
pH
0.050
7

• Calculate the pH of a buffer solution containing
  0.25 moles sodium acetate and 0.30 moles acetic
  acid (HOAc) to which 0.20 moles HCl are added.
• pKa (HOAc) 4.74.

1. 3.74
2. 4.24
3. 4.74

1. 5.24
2. 5.74

8
Correct Answer

1. 3.74
2. 4.24
3. 4.74

1. 5.24
2. 5.74

base


log
4.74
pH
acid
-
0.20
0.25


log
4.74
pH

0.20
0.30
0.05



3.74
log
4.74
pH
0.50
9

• What is the pH of an aqueous solution to which
  51.0 mL of 0.10 M NaOH have been added to 50.0 mL
  0.10 M HCl?

1. 2.00
2. 2.70
3. 3.00
4. 3.30
5. 4.00

10
Correct Answer

1. 2.00
2. 2.70
3. 3.00
4. 3.30
5. 4.00

The solution to problem is on the following
slide.
11
Correct Answer
Moles H (0.10 M)(0.0500 L) 0.0050 Moles OH?
(0.10 M)(0.0490 L) 0.0049
-
0.0049)
(0.0050

?


3

10

1.0




H
?

0.049)
(0.050
pH ?log(1.0 ? 10?3) 3.00
12

• What is the pH of an aqueous solution to which
  26.0 mL of 0.10 M NaOH have been added to 50.0 mL
  0.050 M HCl?

1. 10.00
2. 10.70
3. 11.00
4. 11.30
5. 12.00

13
Correct Answer

1. 10.00
2. 10.70
3. 11.00
4. 11.30
5. 12.00

The solution to problem is on the following
slide.
14
Correct Answer
Moles H (0.050 M)(0.050 L) 0.0025 Moles OH?
(0.10 M)(0.0260 L) 0.0026
-
0.0025)
(0.0026
-
?


3

10

2.0




OH
?

0.025)
(0.026
pOH ?log(2.0 ? 10?3) 2.70 pH 14.00 ? 2.70
11.30
15
What is the molar solubility of BaF2 if its Ksp
1.0 ? 10?6?

1. 3.1 ? 10?3 M
2. 1.0 ? 10?2 M
3. 6.3 ? 10?3 M
4. 8.0 ? 10?3 M

16
Correct Answer

1. 3.1 ? 10?3 M
2. 1.0 ? 10?2 M
3. 6.3 ? 10?3 M
4. 8.0 ? 10?3 M

The solution to problem is on the following
slide.
17
Correct Answer
Ksp Ba2F?2 Let x Ba2 F? 2x. Ksp
(x)(2x)2 4x3 x (Ksp /4)1/3 x 6.3 ? 10?3
18
What is the molar solubility of CaF2 in 0.010 M
NaF? Ksp 3.9 ? 10?11?

1. 9.5 ? 10?6 M
2. 1.9 ? 10?7 M
3. 3.9 ? 10?7M
4. 3.9 ? 10?9 M

19
Correct Answer

1. 9.5 ? 10?6 M
2. 1.9 ? 10?7 M
3. 3.9 ? 10?7M
4. 3.9 ? 10?9 M

The solution to problem is on the following
slide.
20
Correct Answer
Ksp Ca2F?2 Let x Ca2 F? 0.010
2x. Ksp (x)(0.010)2 x Ksp /(0.010)2 x 3.9
? 10?7
21
Which of the following substances will not be
more soluble in acidic solution than basic
solution? The sinkhole below is a dire result of
such solubility.

1. AgCl
2. Ni(OH)2
3. CaCO3
4. BaF2

22
Correct Answer

1. AgCl
2. Ni(OH)2
3. CaCO3
4. BaF2

Of these, only AgCl does not produce a basic
anion that will react with H.
23
Calculate Ag when a NaCN solution is added to
0.10 M AgNO3 (and the equilibrium CN? 0.10 M.
Kf (Ag(CN)2?) 1 ? 1021?

1. 1 ? 10?17 M
2. 1 ? 10?18 M
3. 1 ? 10?19 M

1. 1 ? 10?20 M
2. 1 ? 10?21 M

24
Correct Answer

1. 1 ? 10?17 M
2. 1 ? 10?18 M
3. 1 ? 10?19 M

• 1 ? 10?20 M
• 1 ? 10?21 M

The solution to problem is on the following
slide.
25
Correct Answer

• Kf Ag(CN)2?/AgCN?2
• Assume Ag initially is converted to Ag(CN)2?
• Ag Ag(CN)2?/Kf CN?2
• Ag (0.10)/1 ? 1021(0.1)2
• Ag 1 ? 10?18

26
Upon addition of 6 M HCl to an aqueous solution,
a precipitate forms. Which of the following
cannot be in the precipitate?

1. AgCl
2. Hg2Cl2
3. PbCl2
4. CuCl2

27
Correct Answer

1. AgCl
2. Hg2Cl2
3. PbCl2
4. CuCl2

Chlorides of Ag, Hg22, and Pb2 are insoluble.