Question 1

What is the [H3O+] in a buffer that consists of 0.30 M HCOOH and 0.20 M HCOONa? For HCOOH, Ka = 1.7 × 10-4

Accepted Answer

A)  1.1 × 10-4 M 
B)  2.6 × 10-4 M 
C)  4.3 × 10-4 M 
D)  6.7 × 10-5 M 
E)  none of the above 
A)  1.1 × 10-4 M 
B)  2.6 × 10-4 M 
C)  4.3 × 10-4 M 
D)  6.7 × 10-5 M 
E)  none of the above

Question 2

A solution is prepared by adding 4.50 mol of sodium hydroxide to 1.00 L of 1.00 M Co(NO3)2. What is the equilibrium concentration of cobalt ions? Kf = 5.0 × 109 for Co(OH)42-

Accepted Answer

A)  1.1 × 10-2 M 
B)  1.4 × 10-5 M 
C)  3.2 × 10-9 M 
D)  2.0 × 10-10 M 
E)  4.9 × 10-13 M 
A)  1.1 × 10-2 M 
B)  1.4 × 10-5 M 
C)  3.2 × 10-9 M 
D)  2.0 × 10-10 M 
E)  4.9 × 10-13 M

Question 3

A buffer is prepared by adding 100 mL of 0.50 M sodium hydroxide to 100 mL of 0.75 M propanoic acid. Is this a buffer solution, and if so, what is its pH?

Accepted Answer

A)  It is a buffer, pH > pKa of propanoic acid. 
B)  It is a buffer, pH a of propanoic acid. 
C)  It is a buffer, pH = pKa of propanoic acid. 
D)  It is a buffer, pH = pKb of sodium propanoate. 
E)  Since sodium hydroxide is a strong base, this is not a buffer. 
A)  It is a buffer, pH > pKa of propanoic acid. 
B)  It is a buffer, pH a of propanoic acid. 
C)  It is a buffer, pH = pKa of propanoic acid. 
D)  It is a buffer, pH = pKb of sodium propanoate. 
E)  Since sodium hydroxide is a strong base, this is not a buffer.

Question 4

Which of the following indicators would be the best to use when 0.050 M benzoic acid (Ka = 6.6 × 10-5) is titrated with 0.05 M NaOH?

Accepted Answer

A)  bromphenol blue, pH range: 3.0-4.5 
B)  bromcresol green, pH range: 3.8-5.4 
C)  alizarin, pH range: 5.7-7.2 
D)  phenol red, pH range: 6.9-8.2 
E)  phenolphthalein, pH range: 8.0-10.1 
A)  bromphenol blue, pH range: 3.0-4.5 
B)  bromcresol green, pH range: 3.8-5.4 
C)  alizarin, pH range: 5.7-7.2 
D)  phenol red, pH range: 6.9-8.2 
E)  phenolphthalein, pH range: 8.0-10.1

Question 5

The solubility of silver chloride _______________ when dilute nitric 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 6

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

Accepted Answer

A)  MgCO3, Ksp = 3.5 × 10-8 
B)  NiCO3, Ksp = 1.3 × 10-7 
C)  AgIO3, Ksp = 3.1 × 10-8 
D)  CuBr, Ksp = 5.0 × 10-9 
E)  AgCN, Ksp = 2.2 × 10-16 
A)  MgCO3, Ksp = 3.5 × 10-8 
B)  NiCO3, Ksp = 1.3 × 10-7 
C)  AgIO3, Ksp = 3.1 × 10-8 
D)  CuBr, Ksp = 5.0 × 10-9 
E)  AgCN, Ksp = 2.2 × 10-16

Question 7

A 20.0-mL sample of 0.25 M HNO3 is titrated with 0.15 M NaOH. What is the pH of the solution after 30.0 mL of NaOH have been added to the acid?

Accepted Answer

A)  2.00 
B)  1.60 
C)  1.05 
D)  1.00 
E)  none of the above 
A)  2.00 
B)  1.60 
C)  1.05 
D)  1.00 
E)  none of the above

Question 8

What is the pH of 375 mL of solution containing 0.150 mol of propenoic acid (HA) and 0.250 mol of sodium propenoate (NaA)? (Ka for propenoic acid is 5.52 × 10-5.)

Accepted Answer

Question 9

When a strong 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 equal to the pKa of the acid. 
E)  is equal to the pKb of the base. 
A)  is greater than 7.0. 
B)  is equal to 7.0. 
C)  is less than 7.0. 
D)  is equal to the pKa of the acid. 
E)  is equal to the pKb of the base.

Question 10

What is the pKa for the acid HA if a solution of 0.65 M HA and 0.85 M NaA has a pH of 4.75?

Accepted Answer

A)   5.50 
A)   5.50

Question 11

Which of the following aqueous mixtures would be a buffer system?

Accepted Answer

A)  HCl, NaCl 
B)  HNO3, NaNO3 
C)  H3PO4, H2PO4- 
D)  H2SO4, CH3COOH 
E)  NH3, NaOH 
A)  HCl, NaCl 
B)  HNO3, NaNO3 
C)  H3PO4, H2PO4- 
D)  H2SO4, CH3COOH 
E)  NH3, NaOH

Question 12

Use a carefully drawn and labeled diagram of the titration curve to illustrate the titration of a weak diprotic acid, in which Ka1 and Ka2 are substantially different, with a strong base (base is the titrant). Label as many features of the diagram as possible.

Accepted Answer

Question 13

A 20.0-mL sample of 0.30 M HClO was titrated with 0.30 M NaOH. The following data were collected during the titration.  
What is the Ka for HClO?

Accepted Answer

A)  1.1 × 10-7 
B)  3.5 × 10-8 
C)  1.2 × 10-8 
D)  4.9 × 10-11 
E)  none of the above 
A)  1.1 × 10-7 
B)  3.5 × 10-8 
C)  1.2 × 10-8 
D)  4.9 × 10-11 
E)  none of the above

Question 14

Consider the dissolution of MnS in water
 
How is the solubility of manganese(II) sulfide affected by the addition of aqueous potassium hydroxide to the system?

Accepted Answer

A)  The solubility will be unchanged. 
B)  The solubility will decrease. 
C)  The solubility will increase. 
D)  The amount of KOH added must be known before its effect can be predicted. 
E)  The pKa of H2S is needed before a reliable prediction can be made. 
A)  The solubility will be unchanged. 
B)  The solubility will decrease. 
C)  The solubility will increase. 
D)  The amount of KOH added must be known before its effect can be predicted. 
E)  The pKa of H2S is needed before a reliable prediction can be made.

Question 15

A 25.0-mL sample of 0.35 M HCOOH is titrated with 0.20 M KOH. What is the pH of the solution after 25.0 mL of KOH has been added to the acid? Ka = 1.77 × 10-4

Accepted Answer

A)  4.00 
B)  3.88 
C)  3.63 
D)  3.51 
E)  3.47 
A)  4.00 
B)  3.88 
C)  3.63 
D)  3.51 
E)  3.47

Question 16

Use the following information to calculate the solubility product constant, Ksp, for PbCl2. A saturated solution of PbCl2 in water was prepared and filtered. From the filtrate, 1.0 L was measured out into a beaker and evaporated to dryness. The solid PbCl2 residue recovered in the beaker amounted to 0.0162 moles.

Accepted Answer

A)  Ksp = 6.9 × 10-8 
B)  Ksp = 4.3 × 10-6 
C)  Ksp = 1.7 × 10-5 
D)  Ksp = 2.6 × 10-4 
E)  Ksp = 3.2 × 10-2 
A)  Ksp = 6.9 × 10-8 
B)  Ksp = 4.3 × 10-6 
C)  Ksp = 1.7 × 10-5 
D)  Ksp = 2.6 × 10-4 
E)  Ksp = 3.2 × 10-2

Question 17

What is the [H3O+] in a solution that consists of 1.5 M NH3 and 2.5 NH4Cl? Kb = 1.8 × 10-5

Accepted Answer

A)  1.1 × 10-5 M 
B)  3.0 × 10-6 M 
C)  3.3 × 10-9 M 
D)  9.3 × 10-10 M 
E)  none of the above 
A)  1.1 × 10-5 M 
B)  3.0 × 10-6 M 
C)  3.3 × 10-9 M 
D)  9.3 × 10-10 M 
E)  none of the above

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

A lab technician adds 0.015 mol of KOH to 1.00 L of 0.0010 M Ca(NO3)2. Ksp = 6.5 × 10-6 for Ca(OH)2). Which of the following statements is correct?

Accepted Answer

A)  Calcium hydroxide precipitates until the solution is saturated. 
B)  The solution is unsaturated and no precipitate forms. 
C)  The concentration of calcium ions is reduced by the addition of the hydroxide ions. 
D)  One must know Ksp for calcium nitrate to make meaningful predictions on this system. 
E)  The presence of KOH will raise the solubility of Ca(NO3)2. 
A)  Calcium hydroxide precipitates until the solution is saturated. 
B)  The solution is unsaturated and no precipitate forms. 
C)  The concentration of calcium ions is reduced by the addition of the hydroxide ions. 
D)  One must know Ksp for calcium nitrate to make meaningful predictions on this system. 
E)  The presence of KOH will raise the solubility of Ca(NO3)2.

Question 20

Assuming that the total volume does not change after 0.200 g of KCl is added to 1.0 L of a saturated aqueous solution of AgCl, calculate the number of moles of Ag+ ion in the solution after equilibrium has been reestablished. For AgCl, Ksp = 1.8 × 10- 10.

Accepted Answer

A)  1.8 × 10-10 mol Ag+ 
B)  9.0 × 10-10 mol Ag+ 
C)  9.0 × 10-9 mol Ag+ 
D)  6.7 × 10-8 mol Ag+ 
E)  1.3 × 10-5 mol Ag+ 
A)  1.8 × 10-10 mol Ag+ 
B)  9.0 × 10-10 mol Ag+ 
C)  9.0 × 10-9 mol Ag+ 
D)  6.7 × 10-8 mol Ag+ 
E)  1.3 × 10-5 mol Ag+

Exam 19: Ionic Equilibria in Aqueous Systems

What is the [H3O+] in a buffer that consists of 0.30 M HCOOH and 0.20 M HCOONa? For HCOOH, Ka = 1.7 × 10-4

A solution is prepared by adding 4.50 mol of sodium hydroxide to 1.00 L of 1.00 M Co(NO3)2. What is the equilibrium concentration of cobalt ions? Kf = 5.0 × 109 for Co(OH)42-

A buffer is prepared by adding 100 mL of 0.50 M sodium hydroxide to 100 mL of 0.75 M propanoic acid. Is this a buffer solution, and if so, what is its pH?

Which of the following indicators would be the best to use when 0.050 M benzoic acid (Ka = 6.6 × 10-5) is titrated with 0.05 M NaOH?

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

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

A 20.0-mL sample of 0.25 M HNO3 is titrated with 0.15 M NaOH. What is the pH of the solution after 30.0 mL of NaOH have been added to the acid?

What is the pH of 375 mL of solution containing 0.150 mol of propenoic acid (HA) and 0.250 mol of sodium propenoate (NaA)? (Ka for propenoic acid is 5.52 × 10-5.)

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

What is the pKa for the acid HA if a solution of 0.65 M HA and 0.85 M NaA has a pH of 4.75?

Which of the following aqueous mixtures would be a buffer system?

Use a carefully drawn and labeled diagram of the titration curve to illustrate the titration of a weak diprotic acid, in which Ka1 and Ka2 are substantially different, with a strong base (base is the titrant). Label as many features of the diagram as possible.

A 20.0-mL sample of 0.30 M HClO was titrated with 0.30 M NaOH. The following data were collected during the titration. What is the Ka for HClO?

Consider the dissolution of MnS in water How is the solubility of manganese(II) sulfide affected by the addition of aqueous potassium hydroxide to the system?

A 25.0-mL sample of 0.35 M HCOOH is titrated with 0.20 M KOH. What is the pH of the solution after 25.0 mL of KOH has been added to the acid? Ka = 1.77 × 10-4

What is the [H3O+] in a solution that consists of 1.5 M NH3 and 2.5 NH4Cl? Kb = 1.8 × 10-5

A lab technician adds 0.015 mol of KOH to 1.00 L of 0.0010 M Ca(NO3)2. Ksp = 6.5 × 10-6 for Ca(OH)2). Which of the following statements is correct?

Assuming that the total volume does not change after 0.200 g of KCl is added to 1.0 L of a saturated aqueous solution of AgCl, calculate the number of moles of Ag+ ion in the solution after equilibrium has been reestablished. For AgCl, Ksp = 1.8 × 10- 10.

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 [H₃O⁺] in a buffer that consists of 0.30 M HCOOH and 0.20 M HCOONa? For HCOOH, K_a = 1.7 × 10^-4

A solution is prepared by adding 4.50 mol of sodium hydroxide to 1.00 L of 1.00 M Co(NO₃)₂. What is the equilibrium concentration of cobalt ions? K_f= 5.0 × 10⁹ for Co(OH)₄^2-

Which of the following indicators would be the best to use when 0.050 M benzoic acid (K_a = 6.6 × 10^-5) is titrated with 0.05 M NaOH?

A 20.0-mL sample of 0.25 M HNO₃is titrated with 0.15 M NaOH. What is the pH of the solution after 30.0 mL of NaOH have been added to the acid?

What is the pH of 375 mL of solution containing 0.150 mol of propenoic acid (HA) and 0.250 mol of sodium propenoate (NaA)? (K_a for propenoic acid is 5.52 × 10^-5.)

What is the pK_a for the acid HA if a solution of 0.65 M HA and 0.85 M NaA has a pH of 4.75?

Use a carefully drawn and labeled diagram of the titration curve to illustrate the titration of a weak diprotic acid, in which K_a1 and K_a2 are substantially different, with a strong base (base is the titrant). Label as many features of the diagram as possible.

A 20.0-mL sample of 0.30 M HClO was titrated with 0.30 M NaOH. The following data were collected during the titration. What is the K_a for HClO?

A 25.0-mL sample of 0.35 M HCOOH is titrated with 0.20 M KOH. What is the pH of the solution after 25.0 mL of KOH has been added to the acid? K_a = 1.77 × 10^-4

What is the [H₃O⁺] in a solution that consists of 1.5 M NH₃and 2.5 NH₄Cl? K_b = 1.8 × 10^-5

A lab technician adds 0.015 mol of KOH to 1.00 L of 0.0010 M Ca(NO₃)₂. K_sp = 6.5 × 10^-6 for Ca(OH)₂). Which of the following statements is correct?

Assuming that the total volume does not change after 0.200 g of KCl is added to 1.0 L of a saturated aqueous solution of AgCl, calculate the number of moles of Ag⁺ ion in the solution after equilibrium has been reestablished. For AgCl, K_sp = 1.8 × 10^{- 10}.