Question 1

Which one of the following mixtures would make the best buffer?

Accepted Answer

A)  HI and NaOH 
B)  NaCl and NaOH 
C)  NH3 and CH3COONa 
D)  HF and NaF 
E)  NaOH and HCl 
A)  HI and NaOH 
B)  NaCl and NaOH 
C)  NH3 and CH3COONa 
D)  HF and NaF 
E)  NaOH and HCl

Question 2

Succinic acid (HO2CCH2CH2CO2H) is an intermediate in the Kreb's cycle used to "burn" carbohydrates, proteins and lipids. The formula for succinic acid can be abbreviated as H2Sc.
H2Sc(aq) + H2O(l)   H3O+(aq) + HSc-(aq) &emsp; Ka1 = 6.9 x 10-5
HSc-(aq) + H2O(l)   H3O+(aq) + Sc2-(aq) &emsp; Ka2 = 2.5 x 10-6
Which of the following assumptions may not be valid for solutions of succinic acid because the difference between Ka1 and Ka2 for H2Sc is very small?

Accepted Answer

A)  [H3O+]  $\approx$ Kw/[OH-] 
B)  [H2Sc] 2-] 
C)  [HSc- ]  $\approx$ [H3O+] 
D)  [H2Sc]  $\approx$  CH2Sc 
E)  None of these assumptions are legitimate for this solution. 
A)  [H3O+]  $\approx$ Kw/[OH-] 
B)  [H2Sc] 2-] 
C)  [HSc- ]  $\approx$ [H3O+] 
D)  [H2Sc]  $\approx$  CH2Sc 
E)  None of these assumptions are legitimate for this solution.

Question 3

Use the following information to answer 
HS1U1B12S1U1B0Se: KS1U1B1a1S1U1B0 = 1.0 x 10S1U1P1-4S1S1P0, KS1U1B1a2S1U1B0 = 1.0 x 10S1U1P1-10S1S1P0
-In a 0.10 M solution of H2Se, the Se2- concentration is:

Accepted Answer

A)  [Se2-] = 0.10 x Ka2 = 1.0 x 10-11 
B)  [Se2-] = Ka2 = 1.0 x 10-10 
C)  [Se2-] = (0.10 x Ka2)1/2 = 3.2 x 10-6 
D)  [Se2-] = (0.10 x Ka1)1/2 = 3.2 x 10-3 
E)  none of the above 
A)  [Se2-] = 0.10 x Ka2 = 1.0 x 10-11 
B)  [Se2-] = Ka2 = 1.0 x 10-10 
C)  [Se2-] = (0.10 x Ka2)1/2 = 3.2 x 10-6 
D)  [Se2-] = (0.10 x Ka1)1/2 = 3.2 x 10-3 
E)  none of the above

Question 4

What is the pH of a solution that is simultaneously 0.10 M in both NH3 and the NH4+ ion? 
(NH4+: Ka = 5.6 x 10-10)
NH3(aq) + H2O(l)   NH4+(aq) + OH-(aq)

Accepted Answer

A)  4.75 
B)  7.00 
C)  9.25 
D)  The pH of this solution would be impossible to predict. 
E)  none of the above 
A)  4.75 
B)  7.00 
C)  9.25 
D)  The pH of this solution would be impossible to predict. 
E)  none of the above

Question 5

Which of the following won't produce an acidic solution when dissolved in water?

Accepted Answer

A)  HF 
B)  NH4Cl 
C)  CH3CO2H 
D)  CH3CO2Na 
E)  HClO4 
A)  HF 
B)  NH4Cl 
C)  CH3CO2H 
D)  CH3CO2Na 
E)  HClO4

Question 6

For H2CO3, Ka2 = 4.7 x 10-11. Which of the following numbers is closest to the pH of a 0.200 M Na2CO3 solution? (Hint: Only the first step in the hydrolysis of the CO32- ion need be considered in this calculation.)

Accepted Answer

A)  5.9 x 10-3 
B)  2.2 
C)  2.48 
D)  11.6 
E)  11.8 
A)  5.9 x 10-3 
B)  2.2 
C)  2.48 
D)  11.6 
E)  11.8

Question 7

Which of the following compounds cannot be a base?

Accepted Answer

A)  H2O 
B)  NH3 
C)  CO32- 
D)  OH- 
E)  NH4+ 
A)  H2O 
B)  NH3 
C)  CO32- 
D)  OH- 
E)  NH4+

Question 8

The base-ionization constants for three bases, A(OH), B(OH), and C(OH), are 1.8 x 10-5, 4.4 x 10-4, and 7.4 x 10-4, respectively. Solutions of the bases having equal molarity have pH values that decrease in the following order:

Accepted Answer

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

Question 9

HA is a weak monoprotic acid with Ka = 2.4 x 10-6. What is [OH-] in a 0.300 M solution of the salt, NaA?

Accepted Answer

A)  5.8 x 10-12 
B)  2.4 x 10-10 
C)  3.5 x 10-5 
D)  6.5 x 10-5 
E)  1.6 x 10-3 
A)  5.8 x 10-12 
B)  2.4 x 10-10 
C)  3.5 x 10-5 
D)  6.5 x 10-5 
E)  1.6 x 10-3

Question 10

Predict the products of the following acid-base reaction.
NH4Cl(aq) + NaSH(aq)

Accepted Answer

Question 11

Assume a solution is prepared by adding 1.0 x 10-3 moles of a weak monoprotic acid (Ka = 2.0 x 10-4) to enough water to give a liter of solution. If you want to compute the H3O+ ion concentration with an error of 5% or less, you can legitimately ignore:

Accepted Answer

A)  both the contribution of the dissociation of water and the  $\Delta$ C term. 
B)  neither the dissociation of water nor the  $\Delta$ C term. 
C)  the dissociation of water but not the  $\Delta$ C term. 
D)  the $\Delta$ C term but not the dissociation of water. 
E)  You can't compute the H3O+ concentration with an error of less than 5%. 
A)  both the contribution of the dissociation of water and the  $\Delta$ C term. 
B)  neither the dissociation of water nor the  $\Delta$ C term. 
C)  the dissociation of water but not the  $\Delta$ C term. 
D)  the $\Delta$ C term but not the dissociation of water. 
E)  You can't compute the H3O+ concentration with an error of less than 5%.

Question 12

If equimolar amounts of NH3 and NH4Cl are dissolved in 1.00 L of water, what is the H3O+ ion concentration in this solution? (NH3: Kb = 1.8 x 10-5)

Accepted Answer

A)  1.0 x 10-14 
B)  5.5 x 10-10 
C)  1.0 x 10-7 
D)  1.8 x 10-5 
E)  It cannot be calculated from the information given. 
A)  1.0 x 10-14 
B)  5.5 x 10-10 
C)  1.0 x 10-7 
D)  1.8 x 10-5 
E)  It cannot be calculated from the information given.

Question 13

Using a table of Ka's, determine which of the following is the strongest acid.

Accepted Answer

A)  NH2- 
B)  HS- 
C)  H2O 
D)  CH4 
E)  NH4+ 
A)  NH2- 
B)  HS- 
C)  H2O 
D)  CH4 
E)  NH4+

Question 14

Use the following acid-dissociation equilibrium constants for 
  
-Solutions of each acid are prepared in which the initial concentration of the acid is 0.1000 M. Which of the four solutions will be the most acidic?

Accepted Answer

A)  HA 
B)  HB 
C)  HC 
D)  HD 
E)  Not enough information is provided to answer this question. 
A)  HA 
B)  HB 
C)  HC 
D)  HD 
E)  Not enough information is provided to answer this question.

Question 15

Which of the following would form the most basic 0.100 M solution?

Accepted Answer

A)  NaHSO4 
B)  NaHCO3 
C)  NaH2PO4 
D)  Na2CO3 
E)  NaCl 
A)  NaHSO4 
B)  NaHCO3 
C)  NaH2PO4 
D)  Na2CO3 
E)  NaCl

Question 16

"Cocaine", as it is shown on television, is actually a salt known as cocaine hydrochloride, [C17H22NO4+][Cl-], which forms white crystals that stupid people snort through straws to make them even more stupid. Recently, a lot of attention has been paid to a frightening substance known as "crack", which is formed by treating cocaine with sodium hydrogen carbonate, NaHCO3. "Crack" is a neutral compound with the formula C17H21NO4. Which of the following statements is true?

Accepted Answer

A)  "Crack" is the conjugate base of cocaine hydrochloride. 
B)  "Cocaine" contains the conjugate acid of "crack". 
C)  When "cocaine" is treated with NaHCO3, the bicarbonate ion acts as a base, removing an H+ ion. 
D)  "Crack" can be "smoked" because it is a covalent compound that becomes reasonably volatile when heated, but "cocaine" must be snorted because it is a salt that does not easily boil even when heated. 
E)  All of the above are true. 
A)  "Crack" is the conjugate base of cocaine hydrochloride. 
B)  "Cocaine" contains the conjugate acid of "crack". 
C)  When "cocaine" is treated with NaHCO3, the bicarbonate ion acts as a base, removing an H+ ion. 
D)  "Crack" can be "smoked" because it is a covalent compound that becomes reasonably volatile when heated, but "cocaine" must be snorted because it is a salt that does not easily boil even when heated. 
E)  All of the above are true.

Question 17

Which of the following solutions would be the best buffer capable of resisting change in pH when a small amount of NaOH is added to the solution?

Accepted Answer

A)  a 1.0 L solution prepared by adding 0.10 mol of carbonic acid and 0.10 mol of sodium bicarbonate 
B)  a 1.0 L solution prepared by adding 0.20 mol of carbonic acid and 0.20 mol of sodium bicarbonate 
C)  a 1.0 L solution prepared by adding 0.10 mol of hydrochloric acid and 0.10 mol of sodium hydroxide 
D)  a 1.0 L solution prepared by adding 0.20 mol of hydrochloric acid and 0.20 mol of sodium hydroxide 
E)  All of these solutions would have the same buffer capacity. 
A)  a 1.0 L solution prepared by adding 0.10 mol of carbonic acid and 0.10 mol of sodium bicarbonate 
B)  a 1.0 L solution prepared by adding 0.20 mol of carbonic acid and 0.20 mol of sodium bicarbonate 
C)  a 1.0 L solution prepared by adding 0.10 mol of hydrochloric acid and 0.10 mol of sodium hydroxide 
D)  a 1.0 L solution prepared by adding 0.20 mol of hydrochloric acid and 0.20 mol of sodium hydroxide 
E)  All of these solutions would have the same buffer capacity.

Question 18

Using a table of Ka's, determine which of the following is the strongest base.

Accepted Answer

A)  I- 
B)  NO3- 
C)  HS- 
D)  O2- 
E)  OH- 
A)  I- 
B)  NO3- 
C)  HS- 
D)  O2- 
E)  OH-

Question 19

What would be the effect of doubling the NH3 concentration in the solution described in the previous question?

Accepted Answer

A)  The pH would increase. 
B)  The buffering capacity would increase. 
C)  The NH4+ concentration would increase. 
D)  All of the above statements are true. 
E)  None of these statements are true. 
A)  The pH would increase. 
B)  The buffering capacity would increase. 
C)  The NH4+ concentration would increase. 
D)  All of the above statements are true. 
E)  None of these statements are true.

Question 20

Which of the following isn't true for the H3O+ ion concentration in a
0)0100 M solution of acetic acid (Ka = 1.8 x 10-5)?

Accepted Answer

A)  It is less than the H3O+ concentration in an 0.0100 M solution of HCl. 
B)  It is equal to the OAc- ion concentration. 
C)  It is equal to the OH- ion concentration. 
D)  The pH of the solution is less than 7.0. 
E)  None of the above are true. 
A)  It is less than the H3O+ concentration in an 0.0100 M solution of HCl. 
B)  It is equal to the OAc- ion concentration. 
C)  It is equal to the OH- ion concentration. 
D)  The pH of the solution is less than 7.0. 
E)  None of the above are true.

Which one of the following mixtures would make the best buffer?

Use the following information to answer H₂Se: K_a1 = 1.0 x 10^-4, K_a2 = 1.0 x 10^-10 -In a 0.10 M solution of H₂Se, the Se^2- concentration is:

What is the pH of a solution that is simultaneously 0.10 M in both NH₃ and the NH₄⁺ ion? (NH₄⁺: K_a = 5.6 x 10^-10) NH₃(aq) + H₂O(l) NH₄⁺(aq) + OH^-(aq)

Which of the following won't produce an acidic solution when dissolved in water?

For H₂CO₃, K_a2 = 4.7 x 10^-11. Which of the following numbers is closest to the pH of a 0.200 M Na₂CO₃ solution? (Hint: Only the first step in the hydrolysis of the CO₃^2- ion need be considered in this calculation.)

Which of the following compounds cannot be a base?

The base-ionization constants for three bases, A(OH), B(OH), and C(OH), are 1.8 x 10^-5, 4.4 x 10^-4, and 7.4 x 10^-4, respectively. Solutions of the bases having equal molarity have pH values that decrease in the following order:

HA is a weak monoprotic acid with K_a = 2.4 x 10^-6. What is [OH^-] in a 0.300 M solution of the salt, NaA?

Predict the products of the following acid-base reaction. NH₄Cl(aq) + NaSH(aq)

Assume a solution is prepared by adding 1.0 x 10^-3 moles of a weak monoprotic acid (K_a = 2.0 x 10^-4) to enough water to give a liter of solution. If you want to compute the H₃O⁺ ion concentration with an error of 5% or less, you can legitimately ignore:

If equimolar amounts of NH₃ and NH₄Cl are dissolved in 1.00 L of water, what is the H₃O⁺ ion concentration in this solution? (NH₃: K_b = 1.8 x 10^-5)

Using a table of K_a's, determine which of the following is the strongest acid.

Use the following acid-dissociation equilibrium constants for -Solutions of each acid are prepared in which the initial concentration of the acid is 0.1000 M. Which of the four solutions will be the most acidic?

Which of the following would form the most basic 0.100 M solution?

Which of the following solutions would be the best buffer capable of resisting change in pH when a small amount of NaOH is added to the solution?

Using a table of K_a's, determine which of the following is the strongest base.

What would be the effect of doubling the NH₃ concentration in the solution described in the previous question?

Which of the following isn't true for the H₃O⁺ ion concentration in a 0)0100 M solution of acetic acid (K_a = 1.8 x 10^-5)?

Elements Compounds

The Mole

Structure of the Atom

The Covalent Bond

Ionic and Metallic Bonds

Gases

Making and Breaking of Bonds

Liquids and Solutions

Solids

An Introduction to Kinetics and Equilibrium

Oxidation-Reduction Reactions

Chemical Thermodynamics

Kinetics

Nuclear Chemistry

Organic Chemistry

Filters

Exam 11: Acids and Bases

Which one of the following mixtures would make the best buffer?

Use the following information to answer H2Se: Ka1 = 1.0 x 10-4, Ka2 = 1.0 x 10-10 -In a 0.10 M solution of H2Se, the Se2- concentration is:

What is the pH of a solution that is simultaneously 0.10 M in both NH3 and the NH4+ ion? (NH4+: Ka = 5.6 x 10-10) NH3(aq) + H2O(l) NH4+(aq) + OH-(aq)

Which of the following won't produce an acidic solution when dissolved in water?

For H2CO3, Ka2 = 4.7 x 10-11. Which of the following numbers is closest to the pH of a 0.200 M Na2CO3 solution? (Hint: Only the first step in the hydrolysis of the CO32- ion need be considered in this calculation.)

Which of the following compounds cannot be a base?

The base-ionization constants for three bases, A(OH), B(OH), and C(OH), are 1.8 x 10-5, 4.4 x 10-4, and 7.4 x 10-4, respectively. Solutions of the bases having equal molarity have pH values that decrease in the following order:

HA is a weak monoprotic acid with Ka = 2.4 x 10-6. What is [OH-] in a 0.300 M solution of the salt, NaA?

Predict the products of the following acid-base reaction. NH4Cl(aq) + NaSH(aq)

Assume a solution is prepared by adding 1.0 x 10-3 moles of a weak monoprotic acid (Ka = 2.0 x 10-4) to enough water to give a liter of solution. If you want to compute the H3O+ ion concentration with an error of 5% or less, you can legitimately ignore:

If equimolar amounts of NH3 and NH4Cl are dissolved in 1.00 L of water, what is the H3O+ ion concentration in this solution? (NH3: Kb = 1.8 x 10-5)

Using a table of Ka's, determine which of the following is the strongest acid.

Use the following acid-dissociation equilibrium constants for -Solutions of each acid are prepared in which the initial concentration of the acid is 0.1000 M. Which of the four solutions will be the most acidic?

Which of the following would form the most basic 0.100 M solution?

Which of the following solutions would be the best buffer capable of resisting change in pH when a small amount of NaOH is added to the solution?

Using a table of Ka's, determine which of the following is the strongest base.

What would be the effect of doubling the NH3 concentration in the solution described in the previous question?

Which of the following isn't true for the H3O+ ion concentration in a 0)0100 M solution of acetic acid (Ka = 1.8 x 10-5)?

Elements Compounds

The Mole

Structure of the Atom

The Covalent Bond

Ionic and Metallic Bonds

Gases

Making and Breaking of Bonds

Liquids and Solutions

Solids

An Introduction to Kinetics and Equilibrium

Oxidation-Reduction Reactions

Chemical Thermodynamics

Kinetics

Nuclear Chemistry

Organic Chemistry

Filters

Use the following information to answer H₂Se: K_a1 = 1.0 x 10^-4, K_a2 = 1.0 x 10^-10 -In a 0.10 M solution of H₂Se, the Se^2- concentration is:

What is the pH of a solution that is simultaneously 0.10 M in both NH₃ and the NH₄⁺ ion? (NH₄⁺: K_a = 5.6 x 10^-10) NH₃(aq) + H₂O(l) NH₄⁺(aq) + OH^-(aq)

For H₂CO₃, K_a2 = 4.7 x 10^-11. Which of the following numbers is closest to the pH of a 0.200 M Na₂CO₃ solution? (Hint: Only the first step in the hydrolysis of the CO₃^2- ion need be considered in this calculation.)

The base-ionization constants for three bases, A(OH), B(OH), and C(OH), are 1.8 x 10^-5, 4.4 x 10^-4, and 7.4 x 10^-4, respectively. Solutions of the bases having equal molarity have pH values that decrease in the following order:

HA is a weak monoprotic acid with K_a = 2.4 x 10^-6. What is [OH^-] in a 0.300 M solution of the salt, NaA?

Predict the products of the following acid-base reaction. NH₄Cl(aq) + NaSH(aq)

Assume a solution is prepared by adding 1.0 x 10^-3 moles of a weak monoprotic acid (K_a = 2.0 x 10^-4) to enough water to give a liter of solution. If you want to compute the H₃O⁺ ion concentration with an error of 5% or less, you can legitimately ignore:

If equimolar amounts of NH₃ and NH₄Cl are dissolved in 1.00 L of water, what is the H₃O⁺ ion concentration in this solution? (NH₃: K_b = 1.8 x 10^-5)

Using a table of K_a's, determine which of the following is the strongest acid.

Using a table of K_a's, determine which of the following is the strongest base.

What would be the effect of doubling the NH₃ concentration in the solution described in the previous question?

Which of the following isn't true for the H₃O⁺ ion concentration in a 0)0100 M solution of acetic acid (K_a = 1.8 x 10^-5)?