Additional Aspects of Aqueous Equilibria

1
Chemistry The Central Science, 10th
edition Theodore L. Brown, H. Eugene LeMay, Jr.,
and Bruce E. Bursten
Chapter 17 Additional Aspects of Aqueous
Equilibria
Todd Austell, The University of North Carolinai ?
2006, Pearson Prentice Hall
2

• a.
• NH4 0.050 M Cl 0.050 M NH3 0.12 M
• NH4 0.10 M Cl 0.10 M NH3 0.12 M
• N3 0.10 M H 0.30 M Cl 0.10 M
  NH3 0.12 M
• NH4 0.050 M Cl 0.050 M NH3 0.060 M

3

• a.
• NH4 0.050 M Cl 0.050 M NH3 0.12 M
• NH4 0.10 M Cl 0.10 M NH3 0.12 M
• N3 0.10 M H 0.30 M Cl 0.10 M
  NH3 0.12 M
• NH4 0.050 M Cl 0.050 M NH3 0.060 M

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• b.
• There are no spectator ions.
• Cl
• Both NH4 and Cl
• NH4

5

• b.
• There are no spectator ions.
• Cl
• Both NH4 and Cl
• NH4

6

• c.
• NH3(aq) H2O(l) ? NH4(aq) OH(aq)
• NH4(aq) OH(aq) ? NH3(aq) H2O(l)
• H3O(aq) OH(aq) ? 2H2O(l)
• NH4(aq) H2O(l) ? H3O(aq) NH3(aq)

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• c.
• NH3(aq) H2O(l) ? NH4(aq) OH(aq)
• NH4(aq) OH(aq) ? NH3(aq) H2O(l)
• H3O(aq) OH(aq) ? 2H2O(l)
• NH4(aq) H2O(l) ? H3O(aq) NH3(aq)

8

1. All acid-base pairs will function as buffers.
2. HCHO2 and CHO2 will not work as a buffer because
   CHO2 is a spectator ion.
3. HCO3 and CO32 will not work as a buffer because
   HCO3 is a spectator ion.
4. HNO3 and NO3 will not work as a buffer because
   NO3 is a spectator ion.

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1. All acid-base pairs will function as buffers.
2. HCHO2 and CHO2 will not work as a buffer because
   CHO2 is a spectator ion.
3. HCO3 and CO32 will not work as a buffer because
   HCO3 is a spectator ion.
4. HNO3 and NO3 will not work as a buffer because
   NO3 is a spectator ion.

10

• a.
• There is no reaction because C2H3O2 / HC2H3O2 is
  a buffer.
• The NaOH reacts with C2H3O2 converting some of
  it into HC2H3O2.
• The NaOH reacts with HC2H3O2 converting some of
  it into C2H3O2.
• The NaOH is neutralized and all concentrations
  (HC2H3O2 and C2H3O2) remain unchanged.

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• a.
• There is no reaction because C2H3O2 / HC2H3O2 is
  a buffer.
• The NaOH reacts with C2H3O2 converting some of
  it into HC2H3O2.
• The NaOH reacts with HC2H3O2 converting some of
  it into C2H3O2.
• The NaOH is neutralized and all concentrations
  (HC2H3O2 and C2H3O2) remain unchanged.

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• b.
• There is no reaction because C2H3O2 / HC2H3O2 is
  a buffer.
• The HCl reacts with C2H3O2 converting some of it
  into HC2H3O2.
• The HCl is neutralized and all concentrations
  (HC2H3O2 and C2H3O2) remain unchanged.
• The HCl reacts with HC2H3O2 converting some of it
  into C2H3O2.

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• b.
• There is no reaction because C2H3O2 / HC2H3O2 is
  a buffer.
• The HCl reacts with C2H3O2 converting some of it
  into HC2H3O2.
• The HCl is neutralized and all concentrations
  (HC2H3O2 and C2H3O2) remain unchanged.
• The HCl reacts with HC2H3O2 converting some of it
  into C2H3O2.

14

1. pH 9.26
2. pH 7.00
3. pH 4.74
4. pH 1.80

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1. pH 9.26
2. pH 7.00
3. pH 4.74
4. pH 1.80

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1. We need more information to determine pH when
   titrant is added.
2. The pH will remain the same when titrant is
   added.
3. The pH will decrease when titrant is added.
4. The pH will increase when titrant is added.

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1. We need more information to determine pH when
   titrant is added.
2. The pH will remain the same when titrant is
   added.
3. The pH will decrease when titrant is added.
4. The pH will increase when titrant is added.

18

1. The nearly vertical equivalence point portion of
   the titration curve is large for a weak
   acid-strong base titration, and fewer indicators
   undergo their color change so quickly its
   difficult to monitor.
2. The nearly vertical equivalence point portion of
   the titration curve is smaller for a weak
   acid-strong base titration, and fewer indicators
   undergo their color change within this narrow
   range.
3. Many indicators do not change colors at the
   equivalence points of weak acid-strong base
   titrations.
4. Equivalence points at pHs other than 7.00 are
   difficult to determine.

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1. The nearly vertical equivalence point portion of
   the titration curve is large for a weak
   acid-strong base titration, and fewer indicators
   undergo their color change so quickly its
   difficult to monitor.
2. The nearly vertical equivalence point portion of
   the titration curve is smaller for a weak
   acid-strong base titration, and fewer indicators
   undergo their color change within this narrow
   range.
3. Many indicators do not change colors at the
   equivalence points of weak acid-strong base
   titrations.
4. Equivalence points at pHs other than 7.00 are
   difficult to determine.

20

1. AgI is most soluble.
2. AgBr is most soluble.
3. AgCl is most soluble.
4. All of the compounds have equal solubility in
   water.

21

1. AgI is most soluble.
2. AgBr is most soluble.
3. AgCl is most soluble.
4. All of the compounds have equal solubility in
   water.

22

1. They are insoluble in water but dissolve readily
   in the presence of an acid or base.
2. They quickly liquefy if exposed to air at room
   temperature and atmospheric pressure.
3. They are insoluble in acid or base solutions but
   dissolve readily in pure water.
4. They give off hydrogen gas when mixed with water.

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1. They are insoluble in water but dissolve readily
   in the presence of an acid or base.
2. They quickly liquefy if exposed to air at room
   temperature and atmospheric pressure.
3. They are insoluble in acid or base solutions but
   dissolve readily in pure water.
4. They give off hydrogen gas when mixed with water.

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1. Increasing the pressure on the reaction will
   significantly lower the Cu2.
2. An elevated temperature will significantly lower
   the Cu2.
3. A high concentration of H2S and a low
   concentration of H (high pH) will reduce Cu2.
   
4. A low concentration of H2S and a high
   concentration of H (low pH) will reduce Cu2.

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1. Increasing the pressure on the reaction will
   significantly lower the Cu2.
2. An elevated temperature will significantly lower
   the Cu2.
3. A high concentration of H2S and a low
   concentration of H (high pH) will reduce Cu2.
   
4. A low concentration of H2S and a high
   concentration of H (low pH) will reduce Cu2.

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1. The solution definitely contains either Pb2 or
   Hg22 cation.
2. The solution definitely contains the Ag cation.
3. The solution must contain one of the following
   cations Cu2, Bi3, or Cd2.
4. The solution must contain one of the following
   cations Ag, Pb2 or Hg22.

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1. The solution definitely contains either Pb2 or
   Hg22 cation.
2. The solution definitely contains the Ag cation.
3. The solution must contain one of the following
   cations Cu2, Bi3, or Cd2.
4. The solution must contain one of the following
   cations Ag, Pb2 or Hg22.