Question 1

Explain how a buffer solution manages to stabilize the pH against the addition of acid, base, or additional solvent (dilution).

Accepted Answer

A buffer consists of a weak acid and its

Question 2

Which of the following is not a buffer system? A solution containing roughly equal concentrations of __________

Accepted Answer

A)  fluoride ion and hydrofluoric acid. 
B)  bromide ion and hydrobromic acid. 
C)  phosphate ion and hydrogen phosphate ion. 
D)  carbonate ion and hydrogen carbonate ion. 
E)  phosphoric acid and dihydrogen phosphate ion. 
A)  fluoride ion and hydrofluoric acid. 
B)  bromide ion and hydrobromic acid. 
C)  phosphate ion and hydrogen phosphate ion. 
D)  carbonate ion and hydrogen carbonate ion. 
E)  phosphoric acid and dihydrogen phosphate ion.

Question 3

The analysis label on a 500 mL bottle of Fiji Natural Artesian Water reports pH = 7.5 and 140 mg of bicarbonates, HCO3-. Calculate the pH expected as a result of the bicarbonates to see if these two numbers are consistent with each other. (Kb = 2.4 F1F1F1S1F1F1F10 10-8 for HCO3-)

Accepted Answer

A)  7.5 
B)  5.0 
C)  9.6 
D)  4.4 
E)  9.0 
A)  7.5 
B)  5.0 
C)  9.6 
D)  4.4 
E)  9.0

Question 4

The concentration of acetic acid (pKa = 4.75) in vinegar is about 1.0 M. With this information, what do you predict the pH of vinegar to be?

Accepted Answer

Question 5

Which one of the following is a conjugate acid-base pair?

Accepted Answer

A)  NaF and F- 
B)  HNO3 and HNO2 
C)  HI and I- 
D)  NH4+ and NH2- 
E)  H2O and H2O2 
A)  NaF and F- 
B)  HNO3 and HNO2 
C)  HI and I- 
D)  NH4+ and NH2- 
E)  H2O and H2O2

Question 6

Identify all the correct statements about an acid-base buffer solution.
(I) It can be prepared by combining a strong acid with a salt of its conjugate base.
(II) It can be prepared by combining a weak acid with a salt of its conjugate base.
(III) It can be prepared by combining a weak base with its conjugate acid.
(IV) The pH of a buffer solution does not change when the solution is diluted.
(V) A buffer solution resists changes in its pH when an acid or base is added to it.

Accepted Answer

A)  I, II, and IV 
B)  II, III, and V 
C)  II, III, IV, and V 
D)  I, II, IV, and V 
E)  II, III, and IV 
A)  I, II, and IV 
B)  II, III, and V 
C)  II, III, IV, and V 
D)  I, II, IV, and V 
E)  II, III, and IV

Question 7

In a titration of monoprotic acids and bases, there is a large change in pH __________

Accepted Answer

A)  at the point where pH = pKa of the acid. 
B)  when the volume of acid is exactly equal to the volume of base. 
C)  when the concentration of acid is exactly equal to the concentration of base. 
D)  when the number of moles of acid is exactly equal to the number of moles of base. 
E)  at the point where pH = pKb of the base. 
A)  at the point where pH = pKa of the acid. 
B)  when the volume of acid is exactly equal to the volume of base. 
C)  when the concentration of acid is exactly equal to the concentration of base. 
D)  when the number of moles of acid is exactly equal to the number of moles of base. 
E)  at the point where pH = pKb of the base.

Question 8

A mining operation needs to separate silver and copper. You are hired as a summer intern in a beautiful Colorado mining town, and one of your tasks is to determine whether this separation can be accomplished by oxidizing the metals to Ag+ and Cu+, each one at a concentration of 0.15 M, and then precipitate one as the chloride salt without precipitate the other. AgCl precipitates first. What is the concentration of the Ag+ remaining in solution when CuCl begins to precipitate? For AgCl, pKsp = 9.74. and for CuCl, pKsp = 6.76.

Accepted Answer

A)  1.57 F1F1F1S1F1F1F10 10-2 M 
B)  1.57 F1F1F1S1F1F1F10 10-4 M 
C)  2.23 F1F1F1S1F1F1F10 10-2 M 
D)  2.23 F1F1F1S1F1F1F10 10-4 M 
E)  3.72 F1F1F1S1F1F1F10 10-3 M 
A)  1.57 F1F1F1S1F1F1F10 10-2 M 
B)  1.57 F1F1F1S1F1F1F10 10-4 M 
C)  2.23 F1F1F1S1F1F1F10 10-2 M 
D)  2.23 F1F1F1S1F1F1F10 10-4 M 
E)  3.72 F1F1F1S1F1F1F10 10-3 M

Question 9

What is the pH of a solution made from 46.20 mL of a 0.0500 nitric acid solution diluted to 100.0 mL?

Accepted Answer

The answer of What is the pH of a solution...

Question 10

Which expression defines the autoionization constant for water, Kw?

Accepted Answer

A)  [H3O+][OH-] 
B)  [H2O][H3O+] 
C)  [OH-][H2O] 
D)  [H4O2+][O2-] 
E)  [H2O][H2O] 
A)  [H3O+][OH-] 
B)  [H2O][H3O+] 
C)  [OH-][H2O] 
D)  [H4O2+][O2-] 
E)  [H2O][H2O]

Question 11

Which ending to the statement is not correct? The weak acid HY will be stronger than the weak acid HZ if __________

Accepted Answer

A)  more Lewis resonance structures can be written for the Y group than for the Z group. 
B)  Y is more electronegative than Z. 
C)  the Y group has more oxygen atoms than the Z group. 
D)  the HF1F1F1S1F1F1F10Y bond is weaker than the HF1F1F1S1F1F1F10Z bond and other things are about the same. 
E)  the Y group contains Br rather than Cl, which is in the Z group. 
A)  more Lewis resonance structures can be written for the Y group than for the Z group. 
B)  Y is more electronegative than Z. 
C)  the Y group has more oxygen atoms than the Z group. 
D)  the HF1F1F1S1F1F1F10Y bond is weaker than the HF1F1F1S1F1F1F10Z bond and other things are about the same. 
E)  the Y group contains Br rather than Cl, which is in the Z group.

Question 12

What is the hydronium ion concentration of a 0.20 M solution of ammonia? The Kb value for ammonia is 1.8 F1F1F1S1F1F1F10 10-5

Accepted Answer

A)  2.8 F1F1F1S1F1F1F10 10-10 
B)  5.5 F1F1F1S1F1F1F10 10-10 
C)  1.8 F1F1F1S1F1F1F10 10-5 
D)  5.2 F1F1F1S1F1F1F10 10-12 
E)  1.9 F1F1F1S1F1F1F10 10-3 
A)  2.8 F1F1F1S1F1F1F10 10-10 
B)  5.5 F1F1F1S1F1F1F10 10-10 
C)  1.8 F1F1F1S1F1F1F10 10-5 
D)  5.2 F1F1F1S1F1F1F10 10-12 
E)  1.9 F1F1F1S1F1F1F10 10-3

Question 13

Phosphoric acid is a triprotic acid, ionizing in the following sequential steps: H3PO4 + H2O   H2PO4- + H3O+ Ka
     
H2PO4- + H2O   HPO42- + H3O+ Ka
    HPO42- + H2O   PO43- + H3O+ Ka
    What is the Kb expression for the base, sodium phosphate?

Accepted Answer

A)    
B)    
C)    
D)    
E)    
A)    
B)    
C)    
D)    
E)

Question 14

The concentration of acetic acid in vinegar is about 1.0 M, and the pH is about 2.4. With this information, what do you expect the pKa of vinegar to be?

Accepted Answer

Question 15

What is the pOH of a 0.20 M solution of ammonia? The Kb value for ammonia is 1.8 F1F1F1S1F1F1F10 10-5

Accepted Answer

A)  4.44 
B)  4.74 
C)  0.70 
D)  2.72 
E)  3.38 
A)  4.44 
B)  4.74 
C)  0.70 
D)  2.72 
E)  3.38

Question 16

In each of the following, the stronger acid is identified and an explanation is given. All except one are correct statements. Which one is not correct?

Accepted Answer

A)  HCl > HF because the HF bond energy is larger than the HCl bond energy. 
B)  HCO3- > H2CO3 because the negative charge stabilizes the loss of a proton. 
C)  CCl3COOH > CH3COOH because electronegative substituents stabilize the conjugate base. 
D)  HBrO3 > HBrO2 because of the additional electronegative oxygen atom. 
E)  ClOH > BrOH because Cl is more electronegative than Br. 
A)  HCl > HF because the HF bond energy is larger than the HCl bond energy. 
B)  HCO3- > H2CO3 because the negative charge stabilizes the loss of a proton. 
C)  CCl3COOH > CH3COOH because electronegative substituents stabilize the conjugate base. 
D)  HBrO3 > HBrO2 because of the additional electronegative oxygen atom. 
E)  ClOH > BrOH because Cl is more electronegative than Br.

Question 17

Which sketch best represents the qualitative molecular view of an aqueous solution of nitric acid? (Water molecules are not shown explicitly.)

Accepted Answer

A)    
B)    
C)    
D)    
A)    
B)    
C)    
D)

Question 18

Four solutions have pH values of 3, 5, 8, and 10. Arrange these in order of increasing acidity, and identify those that are acidic, basic, and neutral.

Accepted Answer

Increasing acidity:

Question 19

Which sketch best represents the qualitative molecular view of an aqueous solution of nitrous acid? (Water molecules are not shown explicitly.)

Accepted Answer

A)    
B)    
C)    
D)    
A)    
B)    
C)    
D)

Question 20

What is the solubility of barium sulfate in a solution containing 0.050 M sodium sulfate? The Ksp value for barium sulfate is 1.1 F1F1F1S1F1F1F10 10-10.

Accepted Answer

A)  7.4 F1F1F1S1F1F1F10 10-6 M 
B)  5.5 F1F1F1S1F1F1F10 10-11 M 
C)  1.0 F1F1F1S1F1F1F10 10-5 M 
D)  2.2 F1F1F1S1F1F1F10 10-9 M 
E)  1.1 F1F1F1S1F1F1F10 10-10 M 
A)  7.4 F1F1F1S1F1F1F10 10-6 M 
B)  5.5 F1F1F1S1F1F1F10 10-11 M 
C)  1.0 F1F1F1S1F1F1F10 10-5 M 
D)  2.2 F1F1F1S1F1F1F10 10-9 M 
E)  1.1 F1F1F1S1F1F1F10 10-10 M

Explain how a buffer solution manages to stabilize the pH against the addition of acid, base, or additional solvent (dilution).

Which of the following is not a buffer system? A solution containing roughly equal concentrations of __________

The analysis label on a 500 mL bottle of Fiji Natural Artesian Water reports pH = 7.5 and 140 mg of bicarbonates, HCO₃^-. Calculate the pH expected as a result of the bicarbonates to see if these two numbers are consistent with each other. (K_b = 2.4  10^-⁸ for HCO₃^-)

The concentration of acetic acid (pK_a = 4.75) in vinegar is about 1.0 M. With this information, what do you predict the pH of vinegar to be?

Which one of the following is a conjugate acid-base pair?

In a titration of monoprotic acids and bases, there is a large change in pH __________

What is the pH of a solution made from 46.20 mL of a 0.0500 nitric acid solution diluted to 100.0 mL?

Which expression defines the autoionization constant for water, K_w?

Which ending to the statement is not correct? The weak acid HY will be stronger than the weak acid HZ if __________

What is the hydronium ion concentration of a 0.20 M solution of ammonia? The K_b value for ammonia is 1.8  10^-⁵

Phosphoric acid is a triprotic acid, ionizing in the following sequential steps: H₃PO₄ + H₂O H₂PO₄^- + H₃O⁺ K_a H₂PO₄^- + H₂O HPO₄²^- + H₃O⁺ K_a HPO₄²^- + H₂O PO₄³^- + H₃O⁺ K_a What is the K_b expression for the base, sodium phosphate?

The concentration of acetic acid in vinegar is about 1.0 M, and the pH is about 2.4. With this information, what do you expect the pK_a of vinegar to be?

What is the pOH of a 0.20 M solution of ammonia? The K_b value for ammonia is 1.8  10^-⁵

In each of the following, the stronger acid is identified and an explanation is given. All except one are correct statements. Which one is not correct?

Which sketch best represents the qualitative molecular view of an aqueous solution of nitric acid? (Water molecules are not shown explicitly.)

Four solutions have pH values of 3, 5, 8, and 10. Arrange these in order of increasing acidity, and identify those that are acidic, basic, and neutral.

Which sketch best represents the qualitative molecular view of an aqueous solution of nitrous acid? (Water molecules are not shown explicitly.)

What is the solubility of barium sulfate in a solution containing 0.050 M sodium sulfate? The K_sp value for barium sulfate is 1.1  10^-¹⁰.

Matter, Energy, and the Origins of the Universe

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Chemical Reactions and Earths Composition

Solution Chemistry and the Hydrosphere

Thermochemistry

Properties of Gases: the Air We Breathe

Electrons in Atoms and Periodic Properties

Chemical Bonding and Climate Change

Molecular Geometry and Bonding Theories

Forces Between Ions and Molecules

Solutions and Their Colligative Properties

The Chemistry of Solids

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Thermodynamics: Spontaneous Processes, Entropy, and Free Energy

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Electrochemistry and the Quest for Clean Energy

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Exam 17: Equilibrium in the Aqueous Phase

Explain how a buffer solution manages to stabilize the pH against the addition of acid, base, or additional solvent (dilution).

Which of the following is not a buffer system? A solution containing roughly equal concentrations of __________

The analysis label on a 500 mL bottle of Fiji Natural Artesian Water reports pH = 7.5 and 140 mg of bicarbonates, HCO3-. Calculate the pH expected as a result of the bicarbonates to see if these two numbers are consistent with each other. (Kb = 2.4  10-8 for HCO3-)

The concentration of acetic acid (pKa = 4.75) in vinegar is about 1.0 M. With this information, what do you predict the pH of vinegar to be?

Which one of the following is a conjugate acid-base pair?

In a titration of monoprotic acids and bases, there is a large change in pH __________

What is the pH of a solution made from 46.20 mL of a 0.0500 nitric acid solution diluted to 100.0 mL?

Which expression defines the autoionization constant for water, Kw?

Which ending to the statement is not correct? The weak acid HY will be stronger than the weak acid HZ if __________

What is the hydronium ion concentration of a 0.20 M solution of ammonia? The Kb value for ammonia is 1.8  10-5

Phosphoric acid is a triprotic acid, ionizing in the following sequential steps: H3PO4 + H2O H2PO4- + H3O+ Ka H2PO4- + H2O HPO42- + H3O+ Ka HPO42- + H2O PO43- + H3O+ Ka What is the Kb expression for the base, sodium phosphate?

The concentration of acetic acid in vinegar is about 1.0 M, and the pH is about 2.4. With this information, what do you expect the pKa of vinegar to be?

What is the pOH of a 0.20 M solution of ammonia? The Kb value for ammonia is 1.8  10-5

In each of the following, the stronger acid is identified and an explanation is given. All except one are correct statements. Which one is not correct?

Which sketch best represents the qualitative molecular view of an aqueous solution of nitric acid? (Water molecules are not shown explicitly.)

Four solutions have pH values of 3, 5, 8, and 10. Arrange these in order of increasing acidity, and identify those that are acidic, basic, and neutral.

Which sketch best represents the qualitative molecular view of an aqueous solution of nitrous acid? (Water molecules are not shown explicitly.)

What is the solubility of barium sulfate in a solution containing 0.050 M sodium sulfate? The Ksp value for barium sulfate is 1.1  10-10.

Matter, Energy, and the Origins of the Universe

Atoms, Ions, and Compounds

Chemical Reactions and Earths Composition

Solution Chemistry and the Hydrosphere

Thermochemistry

Properties of Gases: the Air We Breathe

Electrons in Atoms and Periodic Properties

Chemical Bonding and Climate Change

Molecular Geometry and Bonding Theories

Forces Between Ions and Molecules

Solutions and Their Colligative Properties

The Chemistry of Solids

Organic Chemistry: Fuels, Pharmaceuticals, and Materials

Thermodynamics: Spontaneous Processes, Entropy, and Free Energy

Chemical Kinetics

Chemical Equilibrium

The Colorful Chemistry of Metals

Electrochemistry and the Quest for Clean Energy

Biochemistry: the Compounds of Life

Nuclear Chemistry

Life and the Periodic Table

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The analysis label on a 500 mL bottle of Fiji Natural Artesian Water reports pH = 7.5 and 140 mg of bicarbonates, HCO₃^-. Calculate the pH expected as a result of the bicarbonates to see if these two numbers are consistent with each other. (K_b = 2.4  10^-⁸ for HCO₃^-)

The concentration of acetic acid (pK_a = 4.75) in vinegar is about 1.0 M. With this information, what do you predict the pH of vinegar to be?

Which expression defines the autoionization constant for water, K_w?

What is the hydronium ion concentration of a 0.20 M solution of ammonia? The K_b value for ammonia is 1.8  10^-⁵

Phosphoric acid is a triprotic acid, ionizing in the following sequential steps: H₃PO₄ + H₂O H₂PO₄^- + H₃O⁺ K_a H₂PO₄^- + H₂O HPO₄²^- + H₃O⁺ K_a HPO₄²^- + H₂O PO₄³^- + H₃O⁺ K_a What is the K_b expression for the base, sodium phosphate?

The concentration of acetic acid in vinegar is about 1.0 M, and the pH is about 2.4. With this information, what do you expect the pK_a of vinegar to be?

What is the pOH of a 0.20 M solution of ammonia? The K_b value for ammonia is 1.8  10^-⁵

What is the solubility of barium sulfate in a solution containing 0.050 M sodium sulfate? The K_sp value for barium sulfate is 1.1  10^-¹⁰.