Question 1

A solution is prepared by adding 100 mL of 0.2 M hydrochloric acid to 100 mL of 0.4 M sodium formate. Is this a buffer solution, and if so, what is its pH?

Accepted Answer

A)  It is a buffer, pH > pKa of formic acid. 
B)  It is a buffer, pH a of formic acid. 
C)  It is a buffer, pH = pKa of formic acid. 
D)  It is a buffer, pH = pKb of sodium formate. 
E)  Since hydrochloric acid is a strong acid, this is not a buffer. 
A)  It is a buffer, pH > pKa of formic acid. 
B)  It is a buffer, pH a of formic acid. 
C)  It is a buffer, pH = pKa of formic acid. 
D)  It is a buffer, pH = pKb of sodium formate. 
E)  Since hydrochloric acid is a strong acid, this is not a buffer.

Question 2

What is the pH of a buffer that consists of 0.45 M CH3COOH and 0.35 M CH3COONa? Ka = 1.8 × 10-5

Accepted Answer

A)  4.49 
B)  4.64 
C)  4.85 
D)  5.00 
E)  5.52 
A)  4.49 
B)  4.64 
C)  4.85 
D)  5.00 
E)  5.52

Question 3

Which one of the following is the best representation of the titration curve which will be obtained in the titration of a weak acid (0.10 mol L-1) with a strong base of the same concentration?

Accepted Answer

A)    
B)

C)

D)

E)   
A)    
B)

C)

D)

E)

Question 4

A solution is prepared by dissolving 20.0 g of K2HPO4 and 25.0 g of KH2PO4 in enough water to produce 1.0 L of solution. What is the pH of this buffer? For phosphoric acid (H3PO4), Ka2 = 6.2 × 10-8.

Accepted Answer

A)  7.70 
B)  7.42 
C)  7.21 
D)  7.00 
E)  6.72 
A)  7.70 
B)  7.42 
C)  7.21 
D)  7.00 
E)  6.72

Question 5

If 10.0 g of NaF and 20.0 g of HF are dissolved in water to make one liter of solution, what will the pH be? For HF, Ka = 6.8 × 10-4.

Accepted Answer

A)  7.13 
B)  2.54 
C)  1.57 
D)  3.17 
E)  4.86 
A)  7.13 
B)  2.54 
C)  1.57 
D)  3.17 
E)  4.86

Question 6

The salts X(NO3)2 and Y(NO3)2 (where X+ and Y+ are metal ions) are dissolved in water to give a solution which is 0.1 M in each of them. Using the Ksp values listed below, decide which aqueous reagent, if any, will definitely precipitate X+ before precipitating Y+ from solution. Given Ksp values:
XCl2, 1 × 10-5 YCl2, 1 × 10-10 X(OH)2, 1 × 10-10 Y(OH)2, 1 × 10-5

Accepted Answer

A)  1 M NH3 
B)  1 M HCl 
C)  1 M HNO3 
D)  1 M NaCl 
E)  None of the above reagents will accomplish the precipitation. 
A)  1 M NH3 
B)  1 M HCl 
C)  1 M HNO3 
D)  1 M NaCl 
E)  None of the above reagents will accomplish the precipitation.

Question 7

The solubility of silver chromate is 0.0287 g/1.0 L of solution. What is the Ksp for Ag2CrO4?

Accepted Answer

A)  9.5 × 10-5 
B)  2.4 × 10-5 
C)  2.6 × 10-12 
D)  6.5 × 10-13 
E)  -13 
A)  9.5 × 10-5 
B)  2.4 × 10-5 
C)  2.6 × 10-12 
D)  6.5 × 10-13 
E)  -13

Question 8

Calculate the solubility of lead(II) iodide, PbI2, in 0.025 M KI. Ksp = 7.9 × 10-9

Accepted Answer

A)  4.5 × 10-2 M 
B)  2.8 × 10-2 M 
C)  8.9 × 10-5 M 
D)  5.0 × 10-5 M 
E)  1.3 × 10-5 M 
A)  4.5 × 10-2 M 
B)  2.8 × 10-2 M 
C)  8.9 × 10-5 M 
D)  5.0 × 10-5 M 
E)  1.3 × 10-5 M

Question 9

A 50.0-mL sample of 0.50 M HCl is titrated with 0.50 M NaOH. What is the pH of the solution after 28.0 mL of NaOH have been added to the acid?

Accepted Answer

A)  0.85 
B)  0.75 
C)  0.66 
D)  0.49 
E)  3.8 
A)  0.85 
B)  0.75 
C)  0.66 
D)  0.49 
E)  3.8

Question 10

Silver phosphate, Ag3PO4, is an ionic compound with a solubility product constant Ksp of 2.6 × 10-18. Calculate the solubility of this compound in
a. pure water.
b. 0.20 mol L-1 Na3PO4 solution.

Accepted Answer

a. 1.8 × 1

Question 11

What is the pH of a buffer that consists of 0.20 M NaH2PO4 and 0.40 M Na2HPO4? For NaH2PO4, Ka = 6.2 × 10-8

Accepted Answer

A)  6.51 
B)  6.91 
C)  7.51 
D)  7.90 
E)  8.13 
A)  6.51 
B)  6.91 
C)  7.51 
D)  7.90 
E)  8.13

Question 12

A buffer is prepared by adding 150 mL of 1.0 M NaOH to 250 mL of 1.0 M NaH2PO4. How many moles of HCl must be added to this buffer solution to change the pH by 0.18 units? If necessary, assume the total volume remains unchanged at 400 mL.

Accepted Answer

A)  0.025 mol HCl 
B)  0.063 mol HCl 
C)  0.082 mol HCl 
D)  0.50 mol HCl 
E)  1.0 mol HCl 
A)  0.025 mol HCl 
B)  0.063 mol HCl 
C)  0.082 mol HCl 
D)  0.50 mol HCl 
E)  1.0 mol HCl

Question 13

The salts X(NO3)2 and Y(NO3)2 (where X+ and Y+ are metal ions) are dissolved in water to give a solution which is 0.1 M in each of them. Using the Ksp values listed below, decide which aqueous reagent, if any, will definitely precipitate X+ before precipitating Y+ from solution. Given Ksp values:
XCl2, 1 × 10-5 YCl2, 1 × 10-10 X(OH)2, 1 × 10-10  Y(OH)2, 1 × 10-5

Accepted Answer

A)  1 M NaNO3 
B)  1 M HCl 
C)  1 M HNO3 
D)  1 M NaCl 
E)  None of the above reagents will accomplish the precipitation. 
A)  1 M NaNO3 
B)  1 M HCl 
C)  1 M HNO3 
D)  1 M NaCl 
E)  None of the above reagents will accomplish the precipitation.

Question 14

An acetic acid buffer containing 0.50 M CH3COOH and 0.50 M CH3COONa has a pH of 4.74. What will the pH be after 0.0020 mol of HCl has been added to 100.0 mL of the buffer?

Accepted Answer

A)  4.77 
B)  4.71 
C)  4.68 
D)  4.62 
E)  none of the above 
A)  4.77 
B)  4.71 
C)  4.68 
D)  4.62 
E)  none of the above

Question 15

What is the [H3O+] in a solution that consists of 1.2 M HClO and 2.3 M NaClO? Ka = 3.5 × 10-8

Accepted Answer

A)  7.8 × 10-9 M 
B)  1.8 × 10-8 M 
C)  6.7 × 10-8 M 
D)  1.6 × 10-7 M 
E)  none of the above 
A)  7.8 × 10-9 M 
B)  1.8 × 10-8 M 
C)  6.7 × 10-8 M 
D)  1.6 × 10-7 M 
E)  none of the above

Question 16

Which of the following acids should be used to prepare a buffer with a pH of 4.5?

Accepted Answer

A)  HOC6H4OCOOH, Ka = 1.0 × 10-3 
B)  C6H4(COOH)2, Ka = 2.9 × 10-4 
C)  CH3COOH, Ka = 1.8 × 10-5 
D)  C5H5O5COOH, Ka = 4.0 × 10-6 
E)  HBrO, Ka = 2.3 × 10-9 
A)  HOC6H4OCOOH, Ka = 1.0 × 10-3 
B)  C6H4(COOH)2, Ka = 2.9 × 10-4 
C)  CH3COOH, Ka = 1.8 × 10-5 
D)  C5H5O5COOH, Ka = 4.0 × 10-6 
E)  HBrO, Ka = 2.3 × 10-9

Question 17

Calculate the solubility of silver chromate, Ag2CrO4, in 0.005 M Na2CrO4. Ksp = 2.6 × 10-12

Accepted Answer

A)  1.4 × 10-4 M 
B)  3.4 × 10-5 M 
C)  1.1 × 10-5 M 
D)  1.6 × 10-6 M 
E)  -6 M 
A)  1.4 × 10-4 M 
B)  3.4 × 10-5 M 
C)  1.1 × 10-5 M 
D)  1.6 × 10-6 M 
E)  -6 M

Question 18

If the pH of a buffer solution is greater than the pKa value of the buffer acid, the buffer will have more capacity to neutralize added base than added acid.

Accepted Answer

A) True 
 B)False

Question 19

A saturated solution of calcium hydroxide, Ca(OH)2, is in contact with excess solid Ca(OH)2. Which of the following statements correctly describes what will happen when aqueous HCl (a strong acid) is added to this mixture, and system returns to equilibrium? (For Ca(OH)2, Ksp = 6.5 × 10-6))

Accepted Answer

A)  The solubility of Ca(OH)2 will be unchanged. 
B)  The OH- concentration will decrease and the Ca2+ concentration will increase. 
C)  The OH- concentration will increase and the Ca2+ concentration will decrease. 
D)  The concentrations of both Ca2+ and OH- will increase. 
E)  The solubility of Ca(OH)2 will decrease. 
A)  The solubility of Ca(OH)2 will be unchanged. 
B)  The OH- concentration will decrease and the Ca2+ concentration will increase. 
C)  The OH- concentration will increase and the Ca2+ concentration will decrease. 
D)  The concentrations of both Ca2+ and OH- will increase. 
E)  The solubility of Ca(OH)2 will decrease.

Question 20

Which one of the following aqueous solutions, when mixed with an equal volume of 0.10 mol L-1 aqueous NH3, will produce a buffer solution?

Accepted Answer

A)  0.10 mol L-1 HCl 
B)  0.20 mol L-1 HCl 
C)  0.10 mol L-1 CH3COOH 
D)  0.050 mol L-1 NaOH 
E)  0.20 mol L-1 NH4Cl 
A)  0.10 mol L-1 HCl 
B)  0.20 mol L-1 HCl 
C)  0.10 mol L-1 CH3COOH 
D)  0.050 mol L-1 NaOH 
E)  0.20 mol L-1 NH4Cl

Exam 19: Ionic Equilibria in Aqueous Systems

A solution is prepared by adding 100 mL of 0.2 M hydrochloric acid to 100 mL of 0.4 M sodium formate. Is this a buffer solution, and if so, what is its pH?

What is the pH of a buffer that consists of 0.45 M CH3COOH and 0.35 M CH3COONa? Ka = 1.8 × 10-5

Which one of the following is the best representation of the titration curve which will be obtained in the titration of a weak acid (0.10 mol L-1) with a strong base of the same concentration?

A solution is prepared by dissolving 20.0 g of K2HPO4 and 25.0 g of KH2PO4 in enough water to produce 1.0 L of solution. What is the pH of this buffer? For phosphoric acid (H3PO4), Ka2 = 6.2 × 10-8.

If 10.0 g of NaF and 20.0 g of HF are dissolved in water to make one liter of solution, what will the pH be? For HF, Ka = 6.8 × 10-4.

The solubility of silver chromate is 0.0287 g/1.0 L of solution. What is the Ksp for Ag2CrO4?

Calculate the solubility of lead(II) iodide, PbI2, in 0.025 M KI. Ksp = 7.9 × 10-9

A 50.0-mL sample of 0.50 M HCl is titrated with 0.50 M NaOH. What is the pH of the solution after 28.0 mL of NaOH have been added to the acid?

Silver phosphate, Ag3PO4, is an ionic compound with a solubility product constant Ksp of 2.6 × 10-18. Calculate the solubility of this compound in a. pure water. b. 0.20 mol L-1 Na3PO4 solution.

What is the pH of a buffer that consists of 0.20 M NaH2PO4 and 0.40 M Na2HPO4? For NaH2PO4, Ka = 6.2 × 10-8

A buffer is prepared by adding 150 mL of 1.0 M NaOH to 250 mL of 1.0 M NaH2PO4. How many moles of HCl must be added to this buffer solution to change the pH by 0.18 units? If necessary, assume the total volume remains unchanged at 400 mL.

An acetic acid buffer containing 0.50 M CH3COOH and 0.50 M CH3COONa has a pH of 4.74. What will the pH be after 0.0020 mol of HCl has been added to 100.0 mL of the buffer?

What is the [H3O+] in a solution that consists of 1.2 M HClO and 2.3 M NaClO? Ka = 3.5 × 10-8

Which of the following acids should be used to prepare a buffer with a pH of 4.5?

Calculate the solubility of silver chromate, Ag2CrO4, in 0.005 M Na2CrO4. Ksp = 2.6 × 10-12

If the pH of a buffer solution is greater than the pKa value of the buffer acid, the buffer will have more capacity to neutralize added base than added acid.

A saturated solution of calcium hydroxide, Ca(OH)2, is in contact with excess solid Ca(OH)2. Which of the following statements correctly describes what will happen when aqueous HCl (a strong acid) is added to this mixture, and system returns to equilibrium? (For Ca(OH)2, Ksp = 6.5 × 10-6))

Which one of the following aqueous solutions, when mixed with an equal volume of 0.10 mol L-1 aqueous NH3, will produce a buffer solution?

Keys to the Study of Chemistry

The Components of Matter

Stoichiometry of Formulas and Equations

The Major Classes of Chemical Reactions

Gases and the Kinetic-Molecular Theory

Thermochemistry: Energy Flow and Chemical Change

Quantum Theory and Atomic Structure

Electron Configuration and Chemical Periodicity

Models of Chemical Bonding

The Shapes of Molecules

Theories of Covalent Bonding

Intermolecular Forces: Liquids, Solids, and Phase Changes

The Properties of Mixtures: Solutions and Colloids

Periodic Patterns in the Main Group Elements: Bonding, Structure, and Reactivity

Organic Compounds and the Atomic Properties of Carbon

Kinetics: Rates and Mechanisms of Chemical Reactions

Equilibrium: the Extent of Chemical Reactions

Acid-Base Equilibria

Thermodynamics: Entropy, Free Energy, and the Direction of Chemical Reactions

Electrochemistry: Chemical Change and Electrical Work

The Elements in Nature and Industry

The Transition Elements and Their Coordination Compounds

Nuclear Reactions and Their Applications

Filters

What is the pH of a buffer that consists of 0.45 M CH₃COOH and 0.35 M CH₃COONa? K_a = 1.8 × 10^-5

Which one of the following is the best representation of the titration curve which will be obtained in the titration of a weak acid (0.10 mol L^-1) with a strong base of the same concentration?

A solution is prepared by dissolving 20.0 g of K₂HPO₄ and 25.0 g of KH₂PO₄ in enough water to produce 1.0 L of solution. What is the pH of this buffer? For phosphoric acid (H₃PO₄), K_a2 = 6.2 × 10^-8.

If 10.0 g of NaF and 20.0 g of HF are dissolved in water to make one liter of solution, what will the pH be? For HF, K_a = 6.8 × 10^-4.

The solubility of silver chromate is 0.0287 g/1.0 L of solution. What is the K_sp for Ag₂CrO₄?

Calculate the solubility of lead(II) iodide, PbI₂, in 0.025 M KI. K_sp = 7.9 × 10^-9

Silver phosphate, Ag₃PO₄, is an ionic compound with a solubility product constant K_sp of 2.6 × 10^-18. Calculate the solubility of this compound in a. pure water. b. 0.20 mol L^-1 Na₃PO₄ solution.

What is the pH of a buffer that consists of 0.20 M NaH₂PO₄and 0.40 M Na₂HPO₄? For NaH₂PO₄,K_a = 6.2 × 10^-8

A buffer is prepared by adding 150 mL of 1.0 M NaOH to 250 mL of 1.0 M NaH₂PO₄. How many moles of HCl must be added to this buffer solution to change the pH by 0.18 units? If necessary, assume the total volume remains unchanged at 400 mL.

An acetic acid buffer containing 0.50 M CH₃COOH and 0.50 M CH₃COONa has a pH of 4.74. What will the pH be after 0.0020 mol of HCl has been added to 100.0 mL of the buffer?

What is the [H₃O⁺] in a solution that consists of 1.2 M HClO and 2.3 M NaClO? K_a = 3.5 × 10^-8

Calculate the solubility of silver chromate, Ag₂CrO₄, in 0.005 M Na₂CrO₄. K_sp = 2.6 × 10^-12

If the pH of a buffer solution is greater than the pK_a value of the buffer acid, the buffer will have more capacity to neutralize added base than added acid.

A saturated solution of calcium hydroxide, Ca(OH)₂, is in contact with excess solid Ca(OH)₂. Which of the following statements correctly describes what will happen when aqueous HCl (a strong acid) is added to this mixture, and system returns to equilibrium? (For Ca(OH)₂, K_sp = 6.5 × 10^-6))

Which one of the following aqueous solutions, when mixed with an equal volume of 0.10 mol L^-1 aqueous NH₃, will produce a buffer solution?