Question 1

For which of the following equilibria does Kc correspond to a base-ionization constant,Kb?

Accepted Answer

A) H3O+(aq)+ OH-(aq)   2H2O(l) 
B) HCO3-(aq)+ OH-(aq)   CO32-(aq)+ H2O(l) 
C) HOCl(aq)+ H2O(l)   H3O+(aq)+ OCl-(aq) 
D) CO32-(aq)+ H2O(l)   HCO3-(aq)+ OH-(aq) 
E) HCHO2(aq)+ NH3(aq)   CHO2-(aq)+ NH4+(aq) 
A) H3O+(aq)+ OH-(aq)   2H2O(l) 
B) HCO3-(aq)+ OH-(aq)   CO32-(aq)+ H2O(l) 
C) HOCl(aq)+ H2O(l)   H3O+(aq)+ OCl-(aq) 
D) CO32-(aq)+ H2O(l)   HCO3-(aq)+ OH-(aq) 
E) HCHO2(aq)+ NH3(aq)   CHO2-(aq)+ NH4+(aq)

Question 2

A 0.10 M solution of a weak monoprotic acid has a pH of 3.40 at 25°C.What is the acid-ionization constant,Ka,for this acid?

Accepted Answer

A) 1.6 × 10-6 
B) 4.0 × 10-4 
C) 3.4 × 10-5 
D) 1.2 × 10-3 
E) 1.8 × 10-7 
A) 1.6 × 10-6 
B) 4.0 × 10-4 
C) 3.4 × 10-5 
D) 1.2 × 10-3 
E) 1.8 × 10-7

Question 3

Consider the Ka values for the following acids:
Cyanic acid,HOCN,3.5 × 10-4
Formic acid,HCHO2,1.7 × 10-4
Lactic acid,HC3H5O3,1.3 × 10-4
Propionic acid,HC3H5O2,1.3 × 10-5
Benzoic acid,HC7H5O2,6.3 × 10-5
Given initially equimolar soutions of each weak acid,which solution will have the highest hydronium ion concentration once equilibrium is established?

Accepted Answer

A) cyanic acid 
B) benzoic acid 
C) lactic acid 
D) formic acid 
E) propionic acid 
A) cyanic acid 
B) benzoic acid 
C) lactic acid 
D) formic acid 
E) propionic acid

Question 4

Which of the following reactions is associated with the definition of Kb?

Accepted Answer

A) CN-(aq)+ H+(aq)   HCN(aq) 
B) F-(aq)+ H2O(l)   HF(aq)+ OH-(aq) 
C) Zn(OH2)62+(aq)   [Zn(OH2)5OH]+(aq)+ H+(aq) 
D) Cr3+(aq)+ 6H2O(l)   Cr(OH2)63+(aq) 
E) none of these 
A) CN-(aq)+ H+(aq)   HCN(aq) 
B) F-(aq)+ H2O(l)   HF(aq)+ OH-(aq) 
C) Zn(OH2)62+(aq)   [Zn(OH2)5OH]+(aq)+ H+(aq) 
D) Cr3+(aq)+ 6H2O(l)   Cr(OH2)63+(aq) 
E) none of these

Question 5

Saccharin is a weak organic base with a K​b of 4.80 × 10-3.A 0.900-g sample of saccharin dissolved in 45.0mL of water has a pH of 12.310.What is the molar mass of saccharin?

Accepted Answer

A) ​0.458 g/mol 
B) ​43.600 g/mol 
C) ​408.00000 g/mol 
D) ​186 g/mol 
E) ​200 g/mol 
A) ​0.458 g/mol 
B) ​43.600 g/mol 
C) ​408.00000 g/mol 
D) ​186 g/mol 
E) ​200 g/mol

Question 6

In a 0.10 M solution of sodium hydrogen sulfate,the HSO4- ion is 29% dissociated.What is Ka2 for H2SO4?

Accepted Answer

A) 2.4 × 10-1 
B) 1.2 × 10-2 
C) 1.0 × 10-2 
D) 8.4 × 10-3 
E) 2.0 × 10-2 
A) 2.4 × 10-1 
B) 1.2 × 10-2 
C) 1.0 × 10-2 
D) 8.4 × 10-3 
E) 2.0 × 10-2

Question 7

What is Ka for a weak monoprotic acid if a 0.020 M solution of the acid has a pH of 3.28 at 25°C?

Accepted Answer

A) 5.2 × 10-2 
B) 1.4 × 10-5 
C) 7.1 × 10-2 
D) 1.0 × 10-6 
E) 2.8 × 10-4 
A) 5.2 × 10-2 
B) 1.4 × 10-5 
C) 7.1 × 10-2 
D) 1.0 × 10-6 
E) 2.8 × 10-4

Question 8

What is Kc for the following equilibrium? For phosphoric acid (H3PO4),Ka1 = 6.9 × 10-3,Ka2 = 6.2 × 10-8,and Ka3 = 4.8 × 10-13.
HPO42-(aq)+ OH-(aq)  
PO43-(aq)+ H2O(l)

Accepted Answer

A) 7.3 × 10-16 
B) 6.4 × 10-23 
C) 491 
D) 48 
E) 2.3 × 10-35 
A) 7.3 × 10-16 
B) 6.4 × 10-23 
C) 491 
D) 48 
E) 2.3 × 10-35

Question 9

What is the pH of a solution that is 0.14 M in acetic acid,HC2H3O2,and 0.50 M in sodium acetate,NaC2H3O2,at 25°C? Ka of acetic acid is 1.8 × 10-5.

Accepted Answer

A) 4.19 
B) 1.23 
C) 4.74 
D) 2.47 
E) 5.30 
A) 4.19 
B) 1.23 
C) 4.74 
D) 2.47 
E) 5.30

Question 10

What is the hydronium-ion concentration of a 0.30 M solution of HCN (Ka = 4.9 × 10-10)at 25°C?

Accepted Answer

A) 1.7 × 10-4 M 
B) 3.4 × 10-6 M 
C) 2.2 × 10-6 M 
D) 1.2 × 10-5 M 
E) 4.0 × 10-5 M 
A) 1.7 × 10-4 M 
B) 3.4 × 10-6 M 
C) 2.2 × 10-6 M 
D) 1.2 × 10-5 M 
E) 4.0 × 10-5 M

Question 11

What is Ka at 25°C for the following equilibrium?
CH3NH3+(aq)+ H2O(l)  
CH3NH2(aq)+ H3O+(aq)
Kb (CH3NH2)= 4.4 × 10-4 at 25°C.

Accepted Answer

A) 4.4 × 10-4 
B) 2.3 × 103 
C) 4.4 × 10-10 
D) 4.4 × 104 
E) 2.3 × 10-11 
A) 4.4 × 10-4 
B) 2.3 × 103 
C) 4.4 × 10-10 
D) 4.4 × 104 
E) 2.3 × 10-11

Question 12

Which of the following substances,if added to a 0.10 M HC2H3O2 solution,would not increase the hydronium-ion concentration?

Accepted Answer

A) Na2CO3(s) 
B) NaHSO4(s) 
C) H2C2O4(s) 
D) HF(l) 
E) HCl(g) 
A) Na2CO3(s) 
B) NaHSO4(s) 
C) H2C2O4(s) 
D) HF(l) 
E) HCl(g)

Question 13

An initially 1.0 M aqueous solution of a weak monoprotic acid has a total ion concentration of   M when equilibrium is established.What is the acid-ionization constant,Ka,of the weak acid? (assume Ca/Ka ≥ 102)

Accepted Answer

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

Question 14

A 25.00-mL sample of propionic acid,HC3H5O2,of unknown concentration was titrated with 0.141 M KOH.The equivalence point was reached when 37.48 mL of base had been added.What is the concentration of the propionate ion at the equivalence point?

Accepted Answer

A) 0.141 M 
B) 0.147 M 
C) 0.0846 M 
D) 0.211 M 
E) 0.128 M 
A) 0.141 M 
B) 0.147 M 
C) 0.0846 M 
D) 0.211 M 
E) 0.128 M

Question 15

In a 0.01 M solution of 1,4-butanedicarboxylic acid,HOOCCH2CH2COOH (Ka1 = 2.9 × 10-5,Ka2 = 5.3 × 10-6),which species is present in the highest concentration?

Accepted Answer

A) HOOCCH2CH2COO-(aq) 
B) HOOCCH2CH2COOH(aq) 
C) H3O+(aq) 
D) (-OOCCH2CH2COO-)(aq) 
E) OH-(aq) 
A) HOOCCH2CH2COO-(aq) 
B) HOOCCH2CH2COOH(aq) 
C) H3O+(aq) 
D) (-OOCCH2CH2COO-)(aq) 
E) OH-(aq)

Question 16

What is the hydronium-ion concentration of a 0.210 M oxalic acid,H2C2O4,solution? For oxalic acid,Ka1 = 5.6 × 10-2 and Ka2 = 5.1 × 10-5.

Accepted Answer

A) 8.4 × 10-2 M 
B) 1.1 × 10-1 M 
C) 1.0 × 10-7 M 
D) 3.2 × 10-3 M 
E) 3.3 × 10-3 M 
A) 8.4 × 10-2 M 
B) 1.1 × 10-1 M 
C) 1.0 × 10-7 M 
D) 3.2 × 10-3 M 
E) 3.3 × 10-3 M

Question 17

Suppose a buffer solution is made from formic acid (HCHO2)and sodium formate (NaCHO2).What is the net ionic equation for the reaction that occurs when a small amount of sodium hydroxide is added to the buffer?

Accepted Answer

A) NaOH(aq)+ HCHO2(aq)→ NaCHO2(aq)+ H2O(l) 
B) Na+(aq)+ HCHO2(aq)→ NaH(aq)+ HCO2+(aq) 
C) OH-(aq)+ HCHO2(aq)→ CHO2-(aq)+ H2O(l) 
D) H3O+(aq)+ OH-(aq)→ 2H2O(l) 
E) NaOH(aq)+ H3O+(aq)→ Na+(aq)+ 2H2O(l) 
A) NaOH(aq)+ HCHO2(aq)→ NaCHO2(aq)+ H2O(l) 
B) Na+(aq)+ HCHO2(aq)→ NaH(aq)+ HCO2+(aq) 
C) OH-(aq)+ HCHO2(aq)→ CHO2-(aq)+ H2O(l) 
D) H3O+(aq)+ OH-(aq)→ 2H2O(l) 
E) NaOH(aq)+ H3O+(aq)→ Na+(aq)+ 2H2O(l)

Question 18

The oxygen-carrying function of blood depends on its being maintained very near a pH of _____.

Accepted Answer

A) ​4.8 
B) ​7.4 
C) ​5.7 
D) ​8.8 
E) ​9.6 
A) ​4.8 
B) ​7.4 
C) ​5.7 
D) ​8.8 
E) ​9.6

Question 19

What is the pH of a solution prepared by adding 0.254 g of ammonium chloride to 115 mL of water? Kb of NH3 is 1.8 × 10-5.

Accepted Answer

A) 5.32 
B) 3.07 
C) 7.00 
D) 8.68 
E) 10.93 
A) 5.32 
B) 3.07 
C) 7.00 
D) 8.68 
E) 10.93

Question 20

Which of the following would be the best mole ratio of conjugate acid to conjugate base for a large buffer capacity?

Accepted Answer

A) 100:1 
B) 1:1 
C) 1:100 
D) 1:10 
E) 10:1 
A) 100:1 
B) 1:1 
C) 1:100 
D) 1:10 
E) 10:1

Exam 16: Acid-Base Equilibria

For which of the following equilibria does Kc correspond to a base-ionization constant,Kb?

A 0.10 M solution of a weak monoprotic acid has a pH of 3.40 at 25°C.What is the acid-ionization constant,Ka,for this acid?

Which of the following reactions is associated with the definition of Kb?

Saccharin is a weak organic base with a K​b of 4.80 × 10-3.A 0.900-g sample of saccharin dissolved in 45.0mL of water has a pH of 12.310.What is the molar mass of saccharin?

In a 0.10 M solution of sodium hydrogen sulfate,the HSO4- ion is 29% dissociated.What is Ka2 for H2SO4?

What is Ka for a weak monoprotic acid if a 0.020 M solution of the acid has a pH of 3.28 at 25°C?

What is Kc for the following equilibrium? For phosphoric acid (H3PO4),Ka1 = 6.9 × 10-3,Ka2 = 6.2 × 10-8,and Ka3 = 4.8 × 10-13. HPO42-(aq)+ OH-(aq) PO43-(aq)+ H2O(l)

What is the pH of a solution that is 0.14 M in acetic acid,HC2H3O2,and 0.50 M in sodium acetate,NaC2H3O2,at 25°C? Ka of acetic acid is 1.8 × 10-5.

What is the hydronium-ion concentration of a 0.30 M solution of HCN (Ka = 4.9 × 10-10)at 25°C?

What is Ka at 25°C for the following equilibrium? CH3NH3+(aq)+ H2O(l) CH3NH2(aq)+ H3O+(aq) Kb (CH3NH2)= 4.4 × 10-4 at 25°C.

Which of the following substances,if added to a 0.10 M HC2H3O2 solution,would not increase the hydronium-ion concentration?

An initially 1.0 M aqueous solution of a weak monoprotic acid has a total ion concentration of M when equilibrium is established.What is the acid-ionization constant,Ka,of the weak acid? (assume Ca/Ka ≥ 102)

A 25.00-mL sample of propionic acid,HC3H5O2,of unknown concentration was titrated with 0.141 M KOH.The equivalence point was reached when 37.48 mL of base had been added.What is the concentration of the propionate ion at the equivalence point?

In a 0.01 M solution of 1,4-butanedicarboxylic acid,HOOCCH2CH2COOH (Ka1 = 2.9 × 10-5,Ka2 = 5.3 × 10-6),which species is present in the highest concentration?

What is the hydronium-ion concentration of a 0.210 M oxalic acid,H2C2O4,solution? For oxalic acid,Ka1 = 5.6 × 10-2 and Ka2 = 5.1 × 10-5.

Suppose a buffer solution is made from formic acid (HCHO2)and sodium formate (NaCHO2).What is the net ionic equation for the reaction that occurs when a small amount of sodium hydroxide is added to the buffer?

The oxygen-carrying function of blood depends on its being maintained very near a pH of _____.

What is the pH of a solution prepared by adding 0.254 g of ammonium chloride to 115 mL of water? Kb of NH3 is 1.8 × 10-5.

Which of the following would be the best mole ratio of conjugate acid to conjugate base for a large buffer capacity?

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Filters

For which of the following equilibria does K_c correspond to a base-ionization constant,K_b?

A 0.10 M solution of a weak monoprotic acid has a pH of 3.40 at 25°C.What is the acid-ionization constant,K_a,for this acid?

Which of the following reactions is associated with the definition of K_b?

Saccharin is a weak organic base with a K_b of 4.80 × 10^-3.A 0.900-g sample of saccharin dissolved in 45.0mL of water has a pH of 12.310.What is the molar mass of saccharin?

In a 0.10 M solution of sodium hydrogen sulfate,the HSO₄^- ion is 29% dissociated.What is Ka₂ for H₂SO₄?

What is K_a for a weak monoprotic acid if a 0.020 M solution of the acid has a pH of 3.28 at 25°C?

What is K_c for the following equilibrium? For phosphoric acid (H₃PO₄),Ka₁ = 6.9 × 10^-3,Ka₂ = 6.2 × 10^-8,and Ka₃ = 4.8 × 10^-13. HPO₄^2-(aq)+ OH^-(aq) PO₄^3-(aq)+ H₂O(l)

What is the pH of a solution that is 0.14 M in acetic acid,HC₂H₃O₂,and 0.50 M in sodium acetate,NaC₂H₃O₂,at 25°C? K_a of acetic acid is 1.8 × 10^-5.

What is the hydronium-ion concentration of a 0.30 M solution of HCN (K_a = 4.9 × 10^-10)at 25°C?

What is K_a at 25°C for the following equilibrium? CH₃NH₃⁺(aq)+ H₂O(l) CH₃NH₂(aq)+ H₃O⁺(aq) K_b (CH₃NH₂)= 4.4 × 10^-4 at 25°C.

Which of the following substances,if added to a 0.10 M HC₂H₃O₂ solution,would not increase the hydronium-ion concentration?

An initially 1.0 M aqueous solution of a weak monoprotic acid has a total ion concentration of M when equilibrium is established.What is the acid-ionization constant,K_a,of the weak acid? (assume C_a/K_a ≥ 10²)

A 25.00-mL sample of propionic acid,HC₃H₅O₂,of unknown concentration was titrated with 0.141 M KOH.The equivalence point was reached when 37.48 mL of base had been added.What is the concentration of the propionate ion at the equivalence point?

In a 0.01 M solution of 1,4-butanedicarboxylic acid,HOOCCH₂CH₂COOH (Ka₁ = 2.9 × 10^-5,Ka₂ = 5.3 × 10^-6),which species is present in the highest concentration?

What is the hydronium-ion concentration of a 0.210 M oxalic acid,H₂C₂O₄,solution? For oxalic acid,Ka₁ = 5.6 × 10^-2 and Ka₂ = 5.1 × 10^-5.

Suppose a buffer solution is made from formic acid (HCHO₂)and sodium formate (NaCHO₂).What is the net ionic equation for the reaction that occurs when a small amount of sodium hydroxide is added to the buffer?

What is the pH of a solution prepared by adding 0.254 g of ammonium chloride to 115 mL of water? K_b of NH₃ is 1.8 × 10^-5.