Question 1

What will be the effect of adding 0.5 mL of 0.1 M HCl to 100 mL of a phosphate buffer in which [H2PO4¯] = [HPO42¯] = 0.35 M?

Accepted Answer

A)  The pH will increase slightly. 
B)  The pH will increase significantly. 
C)  The pH will decrease slightly. 
D)  The pH will decrease significantly. 
E)  Since it is a buffer solution, the pH will not be affected. 
A)  The pH will increase slightly. 
B)  The pH will increase significantly. 
C)  The pH will decrease slightly. 
D)  The pH will decrease significantly. 
E)  Since it is a buffer solution, the pH will not be affected.

Question 2

Which one of the following is the best representation of the titration curve which will be obtained in the titration of a weak diprotic acid H2A (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 3

A lab technician adds 0.20 mol of NaF to 1.00 L of 0.35 M cadmium nitrate, Cd(NO3)2. Which of the following statements is correct? Ksp = 6.44 * 10¯3 for CdF2.

Accepted Answer

A)  Cadmium fluoride precipitates until the solution is saturated. 
B)  The solution is unsaturated and no precipitate forms. 
C)  The solubility of cadmium fluoride is increased by the presence of additional fluoride ions. 
D)  One must know Ksp for cadmium nitrate to make meaningful predictions on this system. 
E)  The presence of NaF will raise the solubility of Cd(NO3)2. 
A)  Cadmium fluoride precipitates until the solution is saturated. 
B)  The solution is unsaturated and no precipitate forms. 
C)  The solubility of cadmium fluoride is increased by the presence of additional fluoride ions. 
D)  One must know Ksp for cadmium nitrate to make meaningful predictions on this system. 
E)  The presence of NaF will raise the solubility of Cd(NO3)2.

Question 4

What is the maximum amount of sodium sulfate that can be added to 1.00 L of 0.0020 M Ca(NO3)2 before precipitation of calcium sulfate begins? Ksp = 2.4 *10¯5 for calcium sulfate

Accepted Answer

A)  1.2 * 10¯2 mol 
B)  4.9 * 10¯3 mol 
C)  3.5 *10¯3 mol 
D)  1.2 * 10¯5 mol 
E)  4.8 * 10¯8 mol 
A)  1.2 * 10¯2 mol 
B)  4.9 * 10¯3 mol 
C)  3.5 *10¯3 mol 
D)  1.2 * 10¯5 mol 
E)  4.8 * 10¯8 mol

Question 5

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 these choices is correct. 
A)  1.1 * 10¯7 
B)  3.5 * 10¯8 
C)  1.2 * 10¯8 
D)  4.9 * 10¯11 
E)  None of these choices is correct.

Question 6

Calculate the solubility of silver oxalate, Ag2C2O4, in pure water. Ksp = 1.0 * 10¯11

Accepted Answer

A)  1.4 *10¯4 M 
B)  8.2 * 10¯5 M 
C)  5.4 * 10¯5 M 
D)  3.2 * 10¯6 M 
E)  2.5 * 10¯12 M 
A)  1.4 *10¯4 M 
B)  8.2 * 10¯5 M 
C)  5.4 * 10¯5 M 
D)  3.2 * 10¯6 M 
E)  2.5 * 10¯12 M

Question 7

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 8

A 10.0-mL sample of 0.75 M CH3CH2COOH is titrated with 0.30 M NaOH. What is the pH of the solution after 22.0 mL of NaOH have been added to the acid? Ka = 1.3 * 10¯5

Accepted Answer

A)  5.75 
B)  4.94 
C)  4.83 
D)  4.02 
E)  3.95 
A)  5.75 
B)  4.94 
C)  4.83 
D)  4.02 
E)  3.95

Question 9

Write the ion product expression for silver sulfide, Ag2S.

Accepted Answer

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

Question 10

Barium sulfate (BaSO4) is a slightly soluble salt, with Ksp = 1.1 * 10¯10. What mass of Ba2+ ions will be present in 1.0 L of a saturated solution of barium sulfate?

Accepted Answer

A)  7 g 
B)  1.0 *10¯5 g 
C)  0.0014 g 
D)  0.0024 g 
E)  > 0.05 g 
A)  7 g 
B)  1.0 *10¯5 g 
C)  0.0014 g 
D)  0.0024 g 
E)  > 0.05 g

Question 11

A 25.0-mL sample of 0.10 M C2H3NH2 (ethylamine) is titrated with 0.15 M HCl. What is the pH of the solution after 9.00 mL of acid have been added to the amine? Kb = 6.5 *10¯4

Accepted Answer

A)  11.08 
B)  10.88 
C)  10.74 
D)  10.55 
E)  10.49 
A)  11.08 
B)  10.88 
C)  10.74 
D)  10.55 
E)  10.49

Question 12

What volume of 0.200 M KOH must be added to 17.5 mL of 0.135 M H3PO4 to reach the third equivalence point?

Accepted Answer

A)  3.94 mL 
B)  11.8 mL 
C)  17.5 mL 
D)  23.6 mL 
E)  35.4 mL 
A)  3.94 mL 
B)  11.8 mL 
C)  17.5 mL 
D)  23.6 mL 
E)  35.4 mL

Question 13

A popular buffer solution consists of carbonate (CO32¯) and hydrogen carbonate (HCO3¯) conjugate acid-base pair. Which, if any, of the following such buffers can neutralize the greatest amount of added hydrochloric acid, while remaining within its buffer range?

Accepted Answer

A)  1 L of 0.9 M CO32¯ and 0.1 M HCO3¯ 
B)  1 L of 0.1 M CO32¯ and 0.9 M HCO3¯ 
C)  1 L of 0.5 M CO32¯ and 0.5 M HCO3¯ 
D)  1 L of 0.1 M CO32¯ and 0.1 M HCO3¯ 
E)  They can all neutralize the same amount of hydrochloric acid. 
A)  1 L of 0.9 M CO32¯ and 0.1 M HCO3¯ 
B)  1 L of 0.1 M CO32¯ and 0.9 M HCO3¯ 
C)  1 L of 0.5 M CO32¯ and 0.5 M HCO3¯ 
D)  1 L of 0.1 M CO32¯ and 0.1 M HCO3¯ 
E)  They can all neutralize the same amount of hydrochloric acid.

Question 14

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 15

The pH of blood is 7.35. It is maintained in part by the buffer system composed of carbonic acid (H2CO3) and the bicarbonate (hydrogen carbonate, HCO3¯) ion. What is the ratio of [bicarbonate]/[carbonic acid] at this pH? For carbonic acid, Ka1 = 4.2 * 10¯7

Accepted Answer

A)  [bicarbonate]/[carbonic acid] = 0.11 
B)  [bicarbonate]/[carbonic acid] = 0.38 
C)  [bicarbonate]/[carbonic acid] = 2.65 
D)  [bicarbonate]/[carbonic acid] = 9.4 
E)  None of these choices is correct. 
A)  [bicarbonate]/[carbonic acid] = 0.11 
B)  [bicarbonate]/[carbonic acid] = 0.38 
C)  [bicarbonate]/[carbonic acid] = 2.65 
D)  [bicarbonate]/[carbonic acid] = 9.4 
E)  None of these choices is correct.

Question 16

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 17

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 18

Make a clear distinction between buffer range and buffer capacity.

Accepted Answer

Buffer range is the range of pH over whi

Question 19

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

Question 20

A buffer is prepared by adding 0.5 mol of solid sodium hydroxide to 1.0 L of 1.0 M acetic acid (CH3COOH). What is the pH of the buffer?

Accepted Answer

A)  The pH will be pKa - 0.30, where pKa is that of acetic acid. 
B)  The pH will be greater than the pKa for acetic acid. 
C)  The pH will be less than the the pKa for acetic acid. 
D)  The pH will be equal to the pKa for acetic acid. 
E)  More information is needed to solve the problem. 
A)  The pH will be pKa - 0.30, where pKa is that of acetic acid. 
B)  The pH will be greater than the pKa for acetic acid. 
C)  The pH will be less than the the pKa for acetic acid. 
D)  The pH will be equal to the pKa for acetic acid. 
E)  More information is needed to solve the problem.

Exam 19: Ionic Equilibria in Aqueous Systems

What will be the effect of adding 0.5 mL of 0.1 M HCl to 100 mL of a phosphate buffer in which [H2PO4¯] = [HPO42¯] = 0.35 M?

Which one of the following is the best representation of the titration curve which will be obtained in the titration of a weak diprotic acid H2A (0.10 mol L¯1) with a strong base of the same concentration?

A lab technician adds 0.20 mol of NaF to 1.00 L of 0.35 M cadmium nitrate, Cd(NO3)2. Which of the following statements is correct? Ksp = 6.44 * 10¯3 for CdF2.

What is the maximum amount of sodium sulfate that can be added to 1.00 L of 0.0020 M Ca(NO3)2 before precipitation of calcium sulfate begins? Ksp = 2.4 *10¯5 for calcium sulfate

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?

Calculate the solubility of silver oxalate, Ag2C2O4, in pure water. Ksp = 1.0 * 10¯11

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

A 10.0-mL sample of 0.75 M CH3CH2COOH is titrated with 0.30 M NaOH. What is the pH of the solution after 22.0 mL of NaOH have been added to the acid? Ka = 1.3 * 10¯5

Write the ion product expression for silver sulfide, Ag2S.

Barium sulfate (BaSO4) is a slightly soluble salt, with Ksp = 1.1 * 10¯10. What mass of Ba2+ ions will be present in 1.0 L of a saturated solution of barium sulfate?

A 25.0-mL sample of 0.10 M C2H3NH2 (ethylamine) is titrated with 0.15 M HCl. What is the pH of the solution after 9.00 mL of acid have been added to the amine? Kb = 6.5 *10¯4

What volume of 0.200 M KOH must be added to 17.5 mL of 0.135 M H3PO4 to reach the third equivalence point?

A popular buffer solution consists of carbonate (CO32¯) and hydrogen carbonate (HCO3¯) conjugate acid-base pair. Which, if any, of the following such buffers can neutralize the greatest amount of added hydrochloric acid, while remaining within its buffer range?

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?

The pH of blood is 7.35. It is maintained in part by the buffer system composed of carbonic acid (H2CO3) and the bicarbonate (hydrogen carbonate, HCO3¯) ion. What is the ratio of [bicarbonate]/[carbonic acid] at this pH? For carbonic acid, Ka1 = 4.2 * 10¯7

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?

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.

Make a clear distinction between buffer range and buffer capacity.

A buffer is prepared by adding 0.5 mol of solid sodium hydroxide to 1.0 L of 1.0 M acetic acid (CH3COOH). What is the pH of the buffer?

Keys to the Study of Chemistry

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 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 will be the effect of adding 0.5 mL of 0.1 M HCl to 100 mL of a phosphate buffer in which [H₂PO₄¯] = [HPO₄²¯] = 0.35 M?

Which one of the following is the best representation of the titration curve which will be obtained in the titration of a weak diprotic acid H₂A (0.10 mol L¯¹) with a strong base of the same concentration?

A lab technician adds 0.20 mol of NaF to 1.00 L of 0.35 M cadmium nitrate, Cd(NO₃)₂. Which of the following statements is correct? K_sp = 6.44 * 10¯³ for CdF₂.

What is the maximum amount of sodium sulfate that can be added to 1.00 L of 0.0020 M Ca(NO₃)₂ before precipitation of calcium sulfate begins? K_sp = 2.4 *10¯⁵ for calcium sulfate

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?

Calculate the solubility of silver oxalate, Ag₂C₂O₄, in pure water. K_sp = 1.0 * 10¯¹¹

A 10.0-mL sample of 0.75 M CH₃CH₂COOH is titrated with 0.30 M NaOH. What is the pH of the solution after 22.0 mL of NaOH have been added to the acid? K_a = 1.3 * 10¯⁵

Write the ion product expression for silver sulfide, Ag₂S.

Barium sulfate (BaSO₄) is a slightly soluble salt, with K_sp = 1.1 * 10¯¹⁰. What mass of Ba²⁺ ions will be present in 1.0 L of a saturated solution of barium sulfate?

A 25.0-mL sample of 0.10 M C₂H₃NH₂ (ethylamine) is titrated with 0.15 M HCl. What is the pH of the solution after 9.00 mL of acid have been added to the amine? K_b = 6.5 *10¯⁴

What volume of 0.200 M KOH must be added to 17.5 mL of 0.135 M H₃PO₄ to reach the third equivalence point?

A popular buffer solution consists of carbonate (CO₃²¯) and hydrogen carbonate (HCO₃¯) conjugate acid-base pair. Which, if any, of the following such buffers can neutralize the greatest amount of added hydrochloric acid, while remaining within its buffer range?

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?

The pH of blood is 7.35. It is maintained in part by the buffer system composed of carbonic acid (H₂CO₃) and the bicarbonate (hydrogen carbonate, HCO₃¯) ion. What is the ratio of [bicarbonate]/[carbonic acid] at this pH? For carbonic acid, K_a1 = 4.2 * 10¯⁷

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 buffer is prepared by adding 0.5 mol of solid sodium hydroxide to 1.0 L of 1.0 M acetic acid (CH₃COOH). What is the pH of the buffer?