Question 1

The indicator propyl red has Ka = 3.3 × 10-6. What would be the approximate pH range over which it would change color?

Accepted Answer

A)  3.5-5.5 
B)  4.5-6.5 
C)  5.5-7.5 
D)  6.5-8.5 
E)  None of these choices are correct. 
A)  3.5-5.5 
B)  4.5-6.5 
C)  5.5-7.5 
D)  6.5-8.5 
E)  None of these choices are correct.

Question 2

When 20.0 mL of 0.15 M hydrochloric acid is mixed with 20.0 mL of 0.10 M sodium hydroxide, the pH of the resulting solution is

Accepted Answer

A)  0.00. 
B)  12.40. 
C)  1.60. 
D)  0.82. 
E)  7.00. 
A)  0.00. 
B)  12.40. 
C)  1.60. 
D)  0.82. 
E)  7.00.

Question 3

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 4

Which of the following substances has the greatest solubility in water?

Accepted Answer

A)  Ba(IO3)2, Ksp = 1.5 × 10-9 
B)  PbF2, Ksp = 3.6 × 10-8 
C)  SrSO4, Ksp = 3.2 × 10-7 
D)  CuCl, Ksp = 1.9 × 10-7 
E)  CdS, Ksp = 1.0 × 10-24 
A)  Ba(IO3)2, Ksp = 1.5 × 10-9 
B)  PbF2, Ksp = 3.6 × 10-8 
C)  SrSO4, Ksp = 3.2 × 10-7 
D)  CuCl, Ksp = 1.9 × 10-7 
E)  CdS, Ksp = 1.0 × 10-24

Question 5

A buffer is to be prepared by adding solid sodium acetate to 0.10 M CH3COOH. Which of the following concentrations of sodium acetate will produce the most effective buffer?

Accepted Answer

A)  3.0 M CH3COONa 
B)  2.5 M CH3COONa 
C)  2.0 M CH3COONa 
D)  1.5 M CH3COONa 
E)  0.30 M CH3COONa 
A)  3.0 M CH3COONa 
B)  2.5 M CH3COONa 
C)  2.0 M CH3COONa 
D)  1.5 M CH3COONa 
E)  0.30 M CH3COONa

Question 6

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 7

Write the ion product expression for magnesium fluoride, MgF2.

Accepted Answer

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

Question 8

The solubility of silver chloride _______________ when dilute nitric acid is added to it.

Accepted Answer

A)  increases 
B)  decreases 
C)  does not change 
D)  first increases, then decreases 
E)  first decreases, then increases 
A)  increases 
B)  decreases 
C)  does not change 
D)  first increases, then decreases 
E)  first decreases, then increases

Question 9

The solubility of lead(II) chloride is 0.45 g/100 mL of solution. What is the Ksp of PbCl2?

Accepted Answer

A)  4.9 × 10-2 
B)  1.7 × 10-5 
C)  8.5 × 10-6 
D)  4.2 × 10-6 
E)  -6 
A)  4.9 × 10-2 
B)  1.7 × 10-5 
C)  8.5 × 10-6 
D)  4.2 × 10-6 
E)  -6

Question 10

When a weak acid is titrated with a weak base, the pH at the equivalence point

Accepted Answer

A)  is greater than 7.0. 
B)  is equal to 7.0. 
C)  is less than 7.0. 
D)  is determined by the sizes of Ka and Kb. 
E)  is no longer affected by addition of base. 
A)  is greater than 7.0. 
B)  is equal to 7.0. 
C)  is less than 7.0. 
D)  is determined by the sizes of Ka and Kb. 
E)  is no longer affected by addition of base.

Question 11

A buffer is prepared by adding 1.00 L of 1.0 M HCl to 750 mL of 1.5 M NaHCOO. What is the pH of this buffer? Ka = 1.7 × 10-4

Accepted Answer

A)  2.87 
B)  3.72 
C)  3.82 
D)  3.95 
E)  4.66 
A)  2.87 
B)  3.72 
C)  3.82 
D)  3.95 
E)  4.66

Question 12

What volume of 0.500 M H2SO4 is needed to react completely with 20.0 mL of 0.400 M LiOH?

Accepted Answer

A)  4.00 mL 
B)  8.00 mL 
C)  12.5 mL 
D)  16.0 mL 
E)  32.0 mL 
A)  4.00 mL 
B)  8.00 mL 
C)  12.5 mL 
D)  16.0 mL 
E)  32.0 mL

Question 13

You need to use KH2PO4 and K2HPO4 to prepare a buffer with a pH of 7.45. Which of the following ratios of [base]/[acid] is required? For phosphoric acid, (H3PO4), Ka2 = 6.2 × 10-8.

Accepted Answer

A)  [base]/[acid] = 1.75 
B)  [base]/[acid] = 1.27 
C)  [base]/[acid] = 1.24 
D)  [base]/[acid] = 0.79 
E)  [base]/[acid] = 0.57 
A)  [base]/[acid] = 1.75 
B)  [base]/[acid] = 1.27 
C)  [base]/[acid] = 1.24 
D)  [base]/[acid] = 0.79 
E)  [base]/[acid] = 0.57

Question 14

When 0.300 g of a diprotic acid was titrated with 0.100 M LiOH, 40.0 mL of the LiOH solution was needed to reach the second equivalence point. Identify the formula of the diprotic acid.

Accepted Answer

A)  H2S 
B)  H2C2O4 
C)  H2C4H4O6 
D)  H2Se 
E)  H2Te 
A)  H2S 
B)  H2C2O4 
C)  H2C4H4O6 
D)  H2Se 
E)  H2Te

Question 15

At the equivalence point in an acid-base titration

Accepted Answer

A)  the [H3O+] equals the Ka of the acid. 
B)  the [H3O+] equals the Ka of the indicator. 
C)  the amounts of acid and base which have been combined are in their stoichiometric ratio. 
D)  the pH is 7.0. 
E)  the pH has reached a maximum. 
A)  the [H3O+] equals the Ka of the acid. 
B)  the [H3O+] equals the Ka of the indicator. 
C)  the amounts of acid and base which have been combined are in their stoichiometric ratio. 
D)  the pH is 7.0. 
E)  the pH has reached a maximum.

Question 16

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 these choices are correct. 
A)  1 M NaNO3 
B)  1 M HCl 
C)  1 M HNO3 
D)  1 M NaCl 
E)  None of these choices are correct.

Question 17

A phosphate buffer (H2PO4-/HPO42-) has a pH of 8.3. Which of the following changes will cause the pH to increase?

Accepted Answer

A)  dissolving a small amount of Na2HPO4 
B)  dissolving a small amount of NaH2PO4 
C)  adding a small amount of dilute hydrochloric acid 
D)  adding a small amount of dilute phosphoric acid 
E)  making the buffer more concentrated by removing some water 
A)  dissolving a small amount of Na2HPO4 
B)  dissolving a small amount of NaH2PO4 
C)  adding a small amount of dilute hydrochloric acid 
D)  adding a small amount of dilute phosphoric acid 
E)  making the buffer more concentrated by removing some water

Question 18

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. Which of the answers gives the concentration of chloride ions will precipitate the most YCl2 without precipitating any XCl2? Given Ksp values: XCl2, 2 × 10-5 YCl2, 1 × 10-10

Accepted Answer

A)  1 M Cl- 
B)  0.1 M Cl- 
C)  0.01 M Cl- 
D)  0.001 M Cl- 
E)  0.0001 M Cl- 
A)  1 M Cl- 
B)  0.1 M Cl- 
C)  0.01 M Cl- 
D)  0.001 M Cl- 
E)  0.0001 M Cl-

Question 19

What mass of NaF must be added to 50.0 mL of a 0.500 M HF solution to achieve a pH of 3.25? For HF, Ka = 7.2 × 10-4.

Accepted Answer

A)  1.3 g 
B)  0.69 g 
C)  6.9 g 
D)  23 g 
E)  1.5 g 
A)  1.3 g 
B)  0.69 g 
C)  6.9 g 
D)  23 g 
E)  1.5 g

Question 20

A buffer is prepared by adding 300.0 mL of 2.0 M NaOH to 500.0 mL of 2.0 M CH3COOH. What is the pH of this buffer? Ka = 1.8 × 10-5

Accepted Answer

A)  4.57 
B)  4.52 
C)  4.87 
D)  4.92 
E)  4.97 
A)  4.57 
B)  4.52 
C)  4.87 
D)  4.92 
E)  4.97

Exam 19: Ionic Equilibria in Aqueous Systems

The indicator propyl red has Ka = 3.3 × 10-6. What would be the approximate pH range over which it would change color?

When 20.0 mL of 0.15 M hydrochloric acid is mixed with 20.0 mL of 0.10 M sodium hydroxide, the pH of the resulting solution is

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

Which of the following substances has the greatest solubility in water?

A buffer is to be prepared by adding solid sodium acetate to 0.10 M CH3COOH. Which of the following concentrations of sodium acetate will produce the most effective buffer?

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.

Write the ion product expression for magnesium fluoride, MgF2.

The solubility of silver chloride _______________ when dilute nitric acid is added to it.

The solubility of lead(II) chloride is 0.45 g/100 mL of solution. What is the Ksp of PbCl2?

When a weak acid is titrated with a weak base, the pH at the equivalence point

A buffer is prepared by adding 1.00 L of 1.0 M HCl to 750 mL of 1.5 M NaHCOO. What is the pH of this buffer? Ka = 1.7 × 10-4

What volume of 0.500 M H2SO4 is needed to react completely with 20.0 mL of 0.400 M LiOH?

You need to use KH2PO4 and K2HPO4 to prepare a buffer with a pH of 7.45. Which of the following ratios of [base]/[acid] is required? For phosphoric acid, (H3PO4), Ka2 = 6.2 × 10-8.

When 0.300 g of a diprotic acid was titrated with 0.100 M LiOH, 40.0 mL of the LiOH solution was needed to reach the second equivalence point. Identify the formula of the diprotic acid.

At the equivalence point in an acid-base titration

A phosphate buffer (H2PO4-/HPO42-) has a pH of 8.3. Which of the following changes will cause the pH to increase?

What mass of NaF must be added to 50.0 mL of a 0.500 M HF solution to achieve a pH of 3.25? For HF, Ka = 7.2 × 10-4.

A buffer is prepared by adding 300.0 mL of 2.0 M NaOH to 500.0 mL of 2.0 M CH3COOH. What is the pH of this buffer? Ka = 1.8 × 10-5

Keys to Studying Chemistry Definitions, Units, and Problem Solving

The Components of Matter

Stoichiometry of Formulas and Equations

Three 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

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 Reaction Direction

Electrochemistry Chemical Change and Electrical Work

The Elements in Nature and Industry

Transition Elements and Their Coordination Compounds

Nuclear Reactions and Their Applications

Filters

The indicator propyl red has K_a = 3.3 × 10^-6. What would be the approximate pH range over which it would change color?

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

A buffer is to be prepared by adding solid sodium acetate to 0.10 M CH₃COOH. Which of the following concentrations of sodium acetate will produce the most effective buffer?

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.

Write the ion product expression for magnesium fluoride, MgF₂.

The solubility of lead(II) chloride is 0.45 g/100 mL of solution. What is the K_sp of PbCl₂?

A buffer is prepared by adding 1.00 L of 1.0 M HCl to 750 mL of 1.5 M NaHCOO. What is the pH of this buffer? K_a = 1.7 × 10^-4

What volume of 0.500 M H₂SO₄ is needed to react completely with 20.0 mL of 0.400 M LiOH?

You need to use KH₂PO₄ and K₂HPO₄ to prepare a buffer with a pH of 7.45. Which of the following ratios of [base]/[acid] is required? For phosphoric acid, (H₃PO₄), K_a2 = 6.2 × 10^-8.

A phosphate buffer (H₂PO₄^-/HPO₄^2-) has a pH of 8.3. Which of the following changes will cause the pH to increase?

What mass of NaF must be added to 50.0 mL of a 0.500 M HF solution to achieve a pH of 3.25? For HF, K_a = 7.2 × 10^-4.

A buffer is prepared by adding 300.0 mL of 2.0 M NaOH to 500.0 mL of 2.0 M CH₃COOH. What is the pH of this buffer? K_a = 1.8 × 10^-5