Question 1

Consider the titration of 50.0 mL of 0.0200 M HClO(aq)with 0.100 M NaOH(aq).What is the formula of the main species in the solution after the addition of 10.0 mL of base?

Accepted Answer

ClO<sup>-</sup>

Question 2

Calculate the ratio of the molarities of HPO42- and H2PO4- ions required to achieve buffering at pH = 7.00.For H3PO4,pKa1 = 2.12,pKa2 = 7.21,and pKa3 = 12.68.

Accepted Answer

A) 0.81 
B) 1.23 
C) 0.62 
D) 0.21 
E) 1.62 
A) 0.81 
B) 1.23 
C) 0.62 
D) 0.21 
E) 1.62 C

Question 3

If the molar solubility of the compound M2A3 is 7.0 * 10-6 M,what is the Ksp for this compound?

Accepted Answer

A) 1.7 * 10-26 
B) 1.8 * 10-24 
C) 2.9 * 10-10 
D) 3.5 * 10-5 
A) 1.7 * 10-26 
B) 1.8 * 10-24 
C) 2.9 * 10-10 
D) 3.5 * 10-5 B

Question 4

For pyridine,pKb = 8.75.What is the pH of an aqueous buffer solution that is 0.300 M C5H5N(aq)and 0.500 M C5H5NHCl(aq)?

Accepted Answer

A) 8.53 
B) 5.25 
C) 8.97 
D) 5.47 
E) 5.03 
A) 8.53 
B) 5.25 
C) 8.97 
D) 5.47 
E) 5.03

Question 5

Which of the following indicators would be most suitable for the titration of 0.10 M lactic acid with 0.10 M KOH(aq)? For lactic acid,pKa = 3.08.

Accepted Answer

A) Methyl orange (pKIn = 3.4) 
B) Thymol blue (pKIn = 1.7) 
C) Alizarin yellow (pKIn = 11.2) 
D) Bromophenol blue (pKIn = 3.9) 
E) Phenol red (pKIn = 7.9) 
A) Methyl orange (pKIn = 3.4) 
B) Thymol blue (pKIn = 1.7) 
C) Alizarin yellow (pKIn = 11.2) 
D) Bromophenol blue (pKIn = 3.9) 
E) Phenol red (pKIn = 7.9)

Question 6

Calculate the ratio of the molarities of CO32- and HCO3- ions required to achieve buffering at pH = 9.0.For H2CO3,pKa1 = 6.37,and pKa2 = 10.00.

Accepted Answer

A) 0.50 
B) 3.16 
C) 1.65 
D) 0.32 
E) 0.61 
A) 0.50 
B) 3.16 
C) 1.65 
D) 0.32 
E) 0.61

Question 7

Silver bromide is most soluble in

Accepted Answer

A) pure H2O(l). 
B) dilute HNO3(aq). 
C) 0.10 M AgNO3(aq). 
D) dilute NH3(aq). 
E) 0.10 M NaCl(aq). 
A) pure H2O(l). 
B) dilute HNO3(aq). 
C) 0.10 M AgNO3(aq). 
D) dilute NH3(aq). 
E) 0.10 M NaCl(aq).

Question 8

For HF,pKa = 3.45.What is the pH of an aqueous buffer solution that is 0.100 M HF(aq)and 0.300 M KF(aq)?

Accepted Answer

A) 10.07 
B) 2.97 
C) 3.45 
D) 3.93 
E) 11.03 
A) 10.07 
B) 2.97 
C) 3.45 
D) 3.93 
E) 11.03

Question 9

When silver ions form a coordination complex with the thiosulfate ion,the latter acts as a Lewis acid.

Accepted Answer

A) True 
 B)False

Question 10

The pH of 0.50 M HNO2(aq)is 1.8.Therefore,the pH of a solution that is 0.50 M HNO2(aq)and 0.10 M KNO2(aq)is greater than 1.8.

Accepted Answer

A) True 
 B)False

Question 11

Which of the following mixtures gives a buffer with a pH less than 7.0? For acetic acid,Ka = 1.8 * 10-5 and for NH3,Kb = 1.8 * 10-5.

Accepted Answer

A) 10 mL of 0.1 M NH3(aq)+ 10 ml of 0.1 M HCl(aq) 
B) 10 mL of 0.1 M aqueous acetic acid + 5.0 mL of 0.1 M NaOH(aq) 
C) 10 mL of 0.1 M aqueous acetic acid + 10 mL of 0.1 M NaOH(aq) 
D) 10 mL of 0.1 M aqueous acetic acid + 10 mL 0f 0.1 M NH3(aq) 
E) 10 mL of 0.1 M NH3(aq)+ 5.0 mL of 0.1 M HCl(aq) 
A) 10 mL of 0.1 M NH3(aq)+ 10 ml of 0.1 M HCl(aq) 
B) 10 mL of 0.1 M aqueous acetic acid + 5.0 mL of 0.1 M NaOH(aq) 
C) 10 mL of 0.1 M aqueous acetic acid + 10 mL of 0.1 M NaOH(aq) 
D) 10 mL of 0.1 M aqueous acetic acid + 10 mL 0f 0.1 M NH3(aq) 
E) 10 mL of 0.1 M NH3(aq)+ 5.0 mL of 0.1 M HCl(aq)

Question 12

The pH of 0.30 M CH3NH2(aq)is 12.0.Therefore,the pH of a solution that is 0.30 M CH3NH2(aq)and 0.10 M CH3NH3Cl(aq)is greater than 12.0.

Accepted Answer

A) True 
 B)False

Question 13

If a small amount of a strong acid is added to buffer made up of a weak acid,HA,and the sodium salt of its conjugate base,NaA,the pH of the buffer solution does not change appreciably because

Accepted Answer

A) the Ka of HA is changed. 
B) the strong acid reacts with A- to give HA,which is a weak acid. 
C) no reaction occurs. 
D) the strong acid reacts with HA to give H2A+. 
E) the strong acid reacts with A- to give H2A+. 
A) the Ka of HA is changed. 
B) the strong acid reacts with A- to give HA,which is a weak acid. 
C) no reaction occurs. 
D) the strong acid reacts with HA to give H2A+. 
E) the strong acid reacts with A- to give H2A+.

Question 14

Choose the effective pH range of a HF/NaF buffer.For HF,Ka = 3.5 * 10-4.

Accepted Answer

A) 6.0-8.0 
B) 9.6-11.6 
C) 5.0-7.0 
D) 0.7-2.7 
E) 2.5-4.5 
A) 6.0-8.0 
B) 9.6-11.6 
C) 5.0-7.0 
D) 0.7-2.7 
E) 2.5-4.5

Question 15

Choose the effective pH range of a pyridine/pyridinium chloride buffer? For pyridine,the value of Kb is 1.8 * 10-9.

Accepted Answer

A) 9.1-11.1 
B) 1.4-3.4 
C) 10.3-12.3 
D) 7.7-9.7 
E) 4.3-6.3 
A) 9.1-11.1 
B) 1.4-3.4 
C) 10.3-12.3 
D) 7.7-9.7 
E) 4.3-6.3

Question 16

What is the concentration of acetate ion at the stoichiometric point in the titration of 0.018 M CH3COOH(aq)with 0.072 M NaOH(aq)? For acetic acid,Ka = 1.8 * 10-5.

Accepted Answer

A) 0.054 M 
B) 0.036 M 
C) 0.018 M 
D) 0.072 M 
E) 0.014 M 
A) 0.054 M 
B) 0.036 M 
C) 0.018 M 
D) 0.072 M 
E) 0.014 M

Question 17

Calculate the equilibrium constant for the reaction that occurs when nitric acid is added to the buffer HA(aq)/NaA(aq).The Ka of HA is 1.2 * 10-5.

Accepted Answer

8.3 * 10<s

Question 18

What is the pH of an aqueous solution that is 0.018 M C6H5NH2 (Kb = 4.3 * 10-10)and 0.12 M C6H5NH3Cl?

Accepted Answer

A) 5.46 
B) 4.63 
C) 3.81 
D) 10.19 
E) 8.54 
A) 5.46 
B) 4.63 
C) 3.81 
D) 10.19 
E) 8.54

Question 19

Assuming no volume change on mixing,what mass of ammonium chloride should be added to 1.00 L of 0.250 M NH3(aq)to produce a buffer of pH 10.10? The molar mass of ammonium chloride is 53.49 g/mol.

Accepted Answer

Question 20

What is the pH at the half-stoichiometric point for the titration of 0.88 M HNO2(aq)with 0.10 M KOH(aq)? For HNO2,Ka = 4.3 * 10-4.

Accepted Answer

A) 3.37 
B) 2.01 
C) 1.86 
D) 7.00 
E) 1.71 
A) 3.37 
B) 2.01 
C) 1.86 
D) 7.00 
E) 1.71

Consider the titration of 50.0 mL of 0.0200 M HClO(aq)with 0.100 M NaOH(aq).What is the formula of the main species in the solution after the addition of 10.0 mL of base?

Calculate the ratio of the molarities of HPO₄^2- and H₂PO₄^- ions required to achieve buffering at pH = 7.00.For H₃PO₄,pK_a1 = 2.12,pK_a2 = 7.21,and pK_a3 = 12.68.

If the molar solubility of the compound M₂A₃ is 7.0 * 10^-⁶ M,what is the K_sp for this compound?

For pyridine,pK_b = 8.75.What is the pH of an aqueous buffer solution that is 0.300 M C₅H₅N(aq)and 0.500 M C₅H₅NHCl(aq)?

Which of the following indicators would be most suitable for the titration of 0.10 M lactic acid with 0.10 M KOH(aq)? For lactic acid,pK_a = 3.08.

Calculate the ratio of the molarities of CO₃²^- and HCO₃^- ions required to achieve buffering at pH = 9.0.For H₂CO₃,pK_a1 = 6.37,and pK_a2 = 10.00.

Silver bromide is most soluble in

For HF,pK_a = 3.45.What is the pH of an aqueous buffer solution that is 0.100 M HF(aq)and 0.300 M KF(aq)?

When silver ions form a coordination complex with the thiosulfate ion,the latter acts as a Lewis acid.

The pH of 0.50 M HNO₂(aq)is 1.8.Therefore,the pH of a solution that is 0.50 M HNO₂(aq)and 0.10 M KNO₂(aq)is greater than 1.8.

Which of the following mixtures gives a buffer with a pH less than 7.0? For acetic acid,K_a = 1.8 * 10^-5 and for NH₃,K_b = 1.8 * 10^-5.

The pH of 0.30 M CH₃NH₂(aq)is 12.0.Therefore,the pH of a solution that is 0.30 M CH₃NH₂(aq)and 0.10 M CH₃NH₃Cl(aq)is greater than 12.0.

If a small amount of a strong acid is added to buffer made up of a weak acid,HA,and the sodium salt of its conjugate base,NaA,the pH of the buffer solution does not change appreciably because

Choose the effective pH range of a HF/NaF buffer.For HF,K_a = 3.5 * 10^-4.

Choose the effective pH range of a pyridine/pyridinium chloride buffer? For pyridine,the value of K_b is 1.8 * 10^-9.

What is the concentration of acetate ion at the stoichiometric point in the titration of 0.018 M CH₃COOH(aq)with 0.072 M NaOH(aq)? For acetic acid,K_a = 1.8 * 10^-5.

Calculate the equilibrium constant for the reaction that occurs when nitric acid is added to the buffer HA(aq)/NaA(aq).The K_a of HA is 1.2 * 10^-5.

What is the pH of an aqueous solution that is 0.018 M C₆H₅NH₂ (K_b = 4.3 * 10^-10)and 0.12 M C₆H₅NH₃Cl?

Assuming no volume change on mixing,what mass of ammonium chloride should be added to 1.00 L of 0.250 M NH₃(aq)to produce a buffer of pH 10.10? The molar mass of ammonium chloride is 53.49 g/mol.

What is the pH at the half-stoichiometric point for the titration of 0.88 M HNO₂(aq)with 0.10 M KOH(aq)? For HNO₂,K_a = 4.3 * 10^-4.

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Exam 13: Aqueous Equilibria

Consider the titration of 50.0 mL of 0.0200 M HClO(aq)with 0.100 M NaOH(aq).What is the formula of the main species in the solution after the addition of 10.0 mL of base?

Calculate the ratio of the molarities of HPO42- and H2PO4- ions required to achieve buffering at pH = 7.00.For H3PO4,pKa1 = 2.12,pKa2 = 7.21,and pKa3 = 12.68.

If the molar solubility of the compound M2A3 is 7.0 * 10-6 M,what is the Ksp for this compound?

For pyridine,pKb = 8.75.What is the pH of an aqueous buffer solution that is 0.300 M C5H5N(aq)and 0.500 M C5H5NHCl(aq)?

Which of the following indicators would be most suitable for the titration of 0.10 M lactic acid with 0.10 M KOH(aq)? For lactic acid,pKa = 3.08.

Calculate the ratio of the molarities of CO32- and HCO3- ions required to achieve buffering at pH = 9.0.For H2CO3,pKa1 = 6.37,and pKa2 = 10.00.

Silver bromide is most soluble in

For HF,pKa = 3.45.What is the pH of an aqueous buffer solution that is 0.100 M HF(aq)and 0.300 M KF(aq)?

When silver ions form a coordination complex with the thiosulfate ion,the latter acts as a Lewis acid.

The pH of 0.50 M HNO2(aq)is 1.8.Therefore,the pH of a solution that is 0.50 M HNO2(aq)and 0.10 M KNO2(aq)is greater than 1.8.

Which of the following mixtures gives a buffer with a pH less than 7.0? For acetic acid,Ka = 1.8 * 10-5 and for NH3,Kb = 1.8 * 10-5.

The pH of 0.30 M CH3NH2(aq)is 12.0.Therefore,the pH of a solution that is 0.30 M CH3NH2(aq)and 0.10 M CH3NH3Cl(aq)is greater than 12.0.

If a small amount of a strong acid is added to buffer made up of a weak acid,HA,and the sodium salt of its conjugate base,NaA,the pH of the buffer solution does not change appreciably because

Choose the effective pH range of a HF/NaF buffer.For HF,Ka = 3.5 * 10-4.

Choose the effective pH range of a pyridine/pyridinium chloride buffer? For pyridine,the value of Kb is 1.8 * 10-9.

What is the concentration of acetate ion at the stoichiometric point in the titration of 0.018 M CH3COOH(aq)with 0.072 M NaOH(aq)? For acetic acid,Ka = 1.8 * 10-5.

Calculate the equilibrium constant for the reaction that occurs when nitric acid is added to the buffer HA(aq)/NaA(aq).The Ka of HA is 1.2 * 10-5.

What is the pH of an aqueous solution that is 0.018 M C6H5NH2 (Kb = 4.3 * 10-10)and 0.12 M C6H5NH3Cl?

Assuming no volume change on mixing,what mass of ammonium chloride should be added to 1.00 L of 0.250 M NH3(aq)to produce a buffer of pH 10.10? The molar mass of ammonium chloride is 53.49 g/mol.

What is the pH at the half-stoichiometric point for the titration of 0.88 M HNO2(aq)with 0.10 M KOH(aq)? For HNO2,Ka = 4.3 * 10-4.

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Molecular Shape and Structure

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Inorganic Materials

Thermodynamics: The First Law

Thermodynamics: The Second and Third Laws

Physical Equilibria

Chemical Equilibria

Acids and Bases

Electrochemistry

Chemical Kinetics

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Calculate the ratio of the molarities of HPO₄^2- and H₂PO₄^- ions required to achieve buffering at pH = 7.00.For H₃PO₄,pK_a1 = 2.12,pK_a2 = 7.21,and pK_a3 = 12.68.

If the molar solubility of the compound M₂A₃ is 7.0 * 10^-⁶ M,what is the K_sp for this compound?

For pyridine,pK_b = 8.75.What is the pH of an aqueous buffer solution that is 0.300 M C₅H₅N(aq)and 0.500 M C₅H₅NHCl(aq)?

Which of the following indicators would be most suitable for the titration of 0.10 M lactic acid with 0.10 M KOH(aq)? For lactic acid,pK_a = 3.08.

Calculate the ratio of the molarities of CO₃²^- and HCO₃^- ions required to achieve buffering at pH = 9.0.For H₂CO₃,pK_a1 = 6.37,and pK_a2 = 10.00.

For HF,pK_a = 3.45.What is the pH of an aqueous buffer solution that is 0.100 M HF(aq)and 0.300 M KF(aq)?

The pH of 0.50 M HNO₂(aq)is 1.8.Therefore,the pH of a solution that is 0.50 M HNO₂(aq)and 0.10 M KNO₂(aq)is greater than 1.8.

Which of the following mixtures gives a buffer with a pH less than 7.0? For acetic acid,K_a = 1.8 * 10^-5 and for NH₃,K_b = 1.8 * 10^-5.

The pH of 0.30 M CH₃NH₂(aq)is 12.0.Therefore,the pH of a solution that is 0.30 M CH₃NH₂(aq)and 0.10 M CH₃NH₃Cl(aq)is greater than 12.0.

Choose the effective pH range of a HF/NaF buffer.For HF,K_a = 3.5 * 10^-4.

Choose the effective pH range of a pyridine/pyridinium chloride buffer? For pyridine,the value of K_b is 1.8 * 10^-9.

What is the concentration of acetate ion at the stoichiometric point in the titration of 0.018 M CH₃COOH(aq)with 0.072 M NaOH(aq)? For acetic acid,K_a = 1.8 * 10^-5.

Calculate the equilibrium constant for the reaction that occurs when nitric acid is added to the buffer HA(aq)/NaA(aq).The K_a of HA is 1.2 * 10^-5.

What is the pH of an aqueous solution that is 0.018 M C₆H₅NH₂ (K_b = 4.3 * 10^-10)and 0.12 M C₆H₅NH₃Cl?

Assuming no volume change on mixing,what mass of ammonium chloride should be added to 1.00 L of 0.250 M NH₃(aq)to produce a buffer of pH 10.10? The molar mass of ammonium chloride is 53.49 g/mol.

What is the pH at the half-stoichiometric point for the titration of 0.88 M HNO₂(aq)with 0.10 M KOH(aq)? For HNO₂,K_a = 4.3 * 10^-4.