Question 1

A 0.10 M aqueous solution of a weak acid HA has a pH of 5.00.What is the value of Ka for HA?

Accepted Answer

A) 1.0 × 10-8 
B) 1.0 × 10-6 
C) 1.0 × 10-7 
D) 1.0 × 10-5 
E) 1.0 × 10-9 
A) 1.0 × 10-8 
B) 1.0 × 10-6 
C) 1.0 × 10-7 
D) 1.0 × 10-5 
E) 1.0 × 10-9

Question 2

For which of the following equilibria does Kc correspond to an acid-ionization constant,Ka?

Accepted Answer

A) NH3(aq)+ H3O+(aq)   NH4+(aq)+ H2O(l) 
B) NH4+(aq)+ OH-(aq)   NH3(aq)+ H2O(l) 
C) F-(aq)+ H2O(l)   HF(aq)+ OH-(aq) 
D) HF(aq)+ OH-(aq)   H2O(l)+ F-(aq) 
E) NH4+(aq)+ H2O(l)   NH3(aq)+ H3O+(aq) 
A) NH3(aq)+ H3O+(aq)   NH4+(aq)+ H2O(l) 
B) NH4+(aq)+ OH-(aq)   NH3(aq)+ H2O(l) 
C) F-(aq)+ H2O(l)   HF(aq)+ OH-(aq) 
D) HF(aq)+ OH-(aq)   H2O(l)+ F-(aq) 
E) NH4+(aq)+ H2O(l)   NH3(aq)+ H3O+(aq)

Question 3

A 0.20 M solution of a weak monoprotic acid is 0.22 % ionized.What is the acid-ionization constant,Ka,for this acid?

Accepted Answer

A) 1.9 × 10-6 
B) 2.2 × 10-6 
C) 1.1 × 10-4 
D) 2.4 × 10-5 
E) 9.7 × 10-7 
A) 1.9 × 10-6 
B) 2.2 × 10-6 
C) 1.1 × 10-4 
D) 2.4 × 10-5 
E) 9.7 × 10-7

Question 4

In the titration of a weak monoprotic acid with a strong base,the pH at the endpoint will be

Accepted Answer

A) equal to the pKa of the weak acid. 
B) less than 7.00. 
C) equal to 7.00. 
D) greater than the pKa of the weak acid. 
E) less than the pKa of the weak acid. 
A) equal to the pKa of the weak acid. 
B) less than 7.00. 
C) equal to 7.00. 
D) greater than the pKa of the weak acid. 
E) less than the pKa of the weak acid.

Question 5

Which of the following statements is true concerning the titration of a weak base by a solution of hydrochloric acid?

Accepted Answer

A) The solution is basic at the equivalence point. 
B) The solution is acidic at the equivalence point. 
C) At the equivalence point,the pH is determined by the hydrolysis of chloride ion. 
D) At the equivalence point,the pH is 7. 
E) At the equivalence point,there is excess hydrochloric acid. 
A) The solution is basic at the equivalence point. 
B) The solution is acidic at the equivalence point. 
C) At the equivalence point,the pH is determined by the hydrolysis of chloride ion. 
D) At the equivalence point,the pH is 7. 
E) At the equivalence point,there is excess hydrochloric acid.

Question 6

Which of the following solutions has the highest hydroxide-ion concentration?

Accepted Answer

A) 0.10 M NH4ClO4 
B) 0.10 M NaI 
C) 0.10 M NaNO3 
D) 0.10 M NH4Cl 
E) 0.10 M NaCN 
A) 0.10 M NH4ClO4 
B) 0.10 M NaI 
C) 0.10 M NaNO3 
D) 0.10 M NH4Cl 
E) 0.10 M NaCN

Question 7

Consider the titration of 300.0 mL of 0.457 M NH3 (Kb = 1.8 ×10-5)with 0.500 M HNO3.After 150.0 mL of 0.500 M HNO3 has been added,what is the pH of the solution?

Accepted Answer

A) 4.83 
B) 9.17 
C) 6.17 
D) 11.17 
E) none of these 
A) 4.83 
B) 9.17 
C) 6.17 
D) 11.17 
E) none of these

Question 8

A sample of ammonia (Kb = 1.8 × 10-5)is titrated with 0.1 M HCl.At the equivalence point,what is the approximate pH of the solution?

Accepted Answer

A) 5 
B) 1 
C) 9 
D) 7 
E) 11 
A) 5 
B) 1 
C) 9 
D) 7 
E) 11

Question 9

Which of the following mixtures will be a buffer when dissolved in a liter of water?

Accepted Answer

A) 0.4 mol NH3 and 0.4 mol HCl 
B) 0.3 mol NaCl and 0.3 mol HCl 
C) 0.1 mol Ca(OH)2 and 0.3 mol HI 
D) 0.2 mol H3PO4 and 0.1 mol NaOH 
E) 0.2 mol HBr and 0.1 mol NaOH 
A) 0.4 mol NH3 and 0.4 mol HCl 
B) 0.3 mol NaCl and 0.3 mol HCl 
C) 0.1 mol Ca(OH)2 and 0.3 mol HI 
D) 0.2 mol H3PO4 and 0.1 mol NaOH 
E) 0.2 mol HBr and 0.1 mol NaOH

Question 10

What is the pOH of a solution prepared by adding 5.98 g of ammonium iodide to 145 mL of water? Kb of NH3 is 1.8 × 10-5.

Accepted Answer

A) 2.65 
B) 11.35 
C) 7.00 
D) 4.90 
E) 9.10 
A) 2.65 
B) 11.35 
C) 7.00 
D) 4.90 
E) 9.10

Question 11

The equilibrium hydronium ion concentration of an initially 0.655 M solution of a monoprotic weak acid is   M.The acid dissociation constant is  
At 25°C.What is the pH of this solution?

Accepted Answer

A) 2.26 
B) 7.00 
C) 11.74 
D) 4.52 
E) 0.18 
A) 2.26 
B) 7.00 
C) 11.74 
D) 4.52 
E) 0.18

Question 12

For which of the following equilibria does Kc correspond to the acid-ionization constant,Ka,of HC2O4-?

Accepted Answer

A) HC2O4-(aq)+ H2O(l)   H2C2O4(aq)+ OH-(aq) 
B) H2C2O4(aq)+ H2O(l)   H3O+(aq)+ HC2O4-(aq) 
C) HC2O4-(aq)+ H2O(l)   H3O+(aq)+ C2O42-(aq) 
D) HC2O4-(aq)+ OH-(aq)   C2O42-(aq)+ H2O(l) 
E) HC2O4-(aq)+ H3O+(aq)   H2C2O4(aq)+ H2O(l) 
A) HC2O4-(aq)+ H2O(l)   H2C2O4(aq)+ OH-(aq) 
B) H2C2O4(aq)+ H2O(l)   H3O+(aq)+ HC2O4-(aq) 
C) HC2O4-(aq)+ H2O(l)   H3O+(aq)+ C2O42-(aq) 
D) HC2O4-(aq)+ OH-(aq)   C2O42-(aq)+ H2O(l) 
E) HC2O4-(aq)+ H3O+(aq)   H2C2O4(aq)+ H2O(l)

Question 13

A weak base is titrated with a hydrochloric acid solution.What is the pH at the equivalence point?

Accepted Answer

A) equal to pKa 
B) equal to 7 
C) equal to pKb 
D) greater than 7 
E) less than 7 
A) equal to pKa 
B) equal to 7 
C) equal to pKb 
D) greater than 7 
E) less than 7

Question 14

Which of the following indicators is most suitable for the titration of a 25.00-mL sample of 0.140 M propionic acid,HC3H5O2,with strong base?

Accepted Answer

A) alizarin yellow (transition pH range: 10.0-12.0) 
B) methyl red (transition pH range: 4.2-6.3) 
C) methyl orange (transition pH range: 3.1-4.4) 
D) thymol blue (transition pH range: 8.0-9.6) 
E) bromothymol blue (transition pH range: 6.2-7.6) 
A) alizarin yellow (transition pH range: 10.0-12.0) 
B) methyl red (transition pH range: 4.2-6.3) 
C) methyl orange (transition pH range: 3.1-4.4) 
D) thymol blue (transition pH range: 8.0-9.6) 
E) bromothymol blue (transition pH range: 6.2-7.6)

Question 15

Carbonic acid,H2CO3,is a weak diprotic acid.In a 0.1 M solution of the acid,which of the following species is present in the largest amount?

Accepted Answer

A) HCO3- 
B) CO32- 
C) H2CO3 
D) H3O+ 
E) OH- 
A) HCO3- 
B) CO32- 
C) H2CO3 
D) H3O+ 
E) OH-

Question 16

What is the pOH of a solution prepared by adding 1.22 g of potassium nitrite to 155 mL of water? Ka of HNO2 is 4.5 × 10-4.

Accepted Answer

A) 11.79 
B) 2.21 
C) 8.15 
D) 7.00 
E) 5.85 
A) 11.79 
B) 2.21 
C) 8.15 
D) 7.00 
E) 5.85

Question 17

Given the following,what will be the approximate equilibrium pH of an aqueous solution of ammonium cyanide,NH4CN?
NH4+
Ka = 5.69 x10-10
HCN
Ka = 6.2 x10-10

Accepted Answer

A) slightly basic 
B) slightly acidic 
C) nearly neutral 
A) slightly basic 
B) slightly acidic 
C) nearly neutral

Question 18

What is the hydronium-ion concentration in a 0.018 M solution of carbonic acid,H2CO3? For carbonic acid,Ka1 = 4.2 × 10-7 and Ka2 = 4.8 × 10-11.

Accepted Answer

A) 1.8 × 10-2 M 
B) 4.2 × 10-7 M 
C) 4.8 × 10-11 M 
D) 8.7 × 10-5 M 
E) 4.3 × 10-5 M 
A) 1.8 × 10-2 M 
B) 4.2 × 10-7 M 
C) 4.8 × 10-11 M 
D) 8.7 × 10-5 M 
E) 4.3 × 10-5 M

Question 19

For which of the following equilibria does Kc correspond to the acid-dissociation constant,Ka,of H2PO4-?

Accepted Answer

A) H2PO4-(aq)+ H3O+(aq)   H3PO4(aq)+ H2O(l) 
B) H2PO4-(aq)+ H2O(l)   H3PO4(aq)+ OH-(aq) 
C) H2PO4-(aq)+ H2O(l)   H3O+(aq)+ HPO42-(aq) 
D) H3PO4(aq)+ H2O(l)   H3O+(aq)+ H2PO4-(aq) 
E) HPO42-(aq)+ H2O(l)   H2PO4-(aq)+ OH-(aq) 
A) H2PO4-(aq)+ H3O+(aq)   H3PO4(aq)+ H2O(l) 
B) H2PO4-(aq)+ H2O(l)   H3PO4(aq)+ OH-(aq) 
C) H2PO4-(aq)+ H2O(l)   H3O+(aq)+ HPO42-(aq) 
D) H3PO4(aq)+ H2O(l)   H3O+(aq)+ H2PO4-(aq) 
E) HPO42-(aq)+ H2O(l)   H2PO4-(aq)+ OH-(aq)

Question 20

In a 0.20 M solution of a diprotic acid H2A (Ka1 = 1.3 × 10-5 and Ka2 = 2.7 × 10-10 at 25°C),what is the equilibrium concentration of A2-?

Accepted Answer

A) 7.3 × 10-6 M 
B) 2.7 × 10-10 M 
C) 1.6 × 10-3 M 
D) 0.40 M 
E) 0.20 M 
A) 7.3 × 10-6 M 
B) 2.7 × 10-10 M 
C) 1.6 × 10-3 M 
D) 0.40 M 
E) 0.20 M

Exam 16: Acid-Base Equilibria

A 0.10 M aqueous solution of a weak acid HA has a pH of 5.00.What is the value of Ka for HA?

For which of the following equilibria does Kc correspond to an acid-ionization constant,Ka?

A 0.20 M solution of a weak monoprotic acid is 0.22 % ionized.What is the acid-ionization constant,Ka,for this acid?

In the titration of a weak monoprotic acid with a strong base,the pH at the endpoint will be

Which of the following statements is true concerning the titration of a weak base by a solution of hydrochloric acid?

Which of the following solutions has the highest hydroxide-ion concentration?

Consider the titration of 300.0 mL of 0.457 M NH3 (Kb = 1.8 ×10-5)with 0.500 M HNO3.After 150.0 mL of 0.500 M HNO3 has been added,what is the pH of the solution?

A sample of ammonia (Kb = 1.8 × 10-5)is titrated with 0.1 M HCl.At the equivalence point,what is the approximate pH of the solution?

Which of the following mixtures will be a buffer when dissolved in a liter of water?

What is the pOH of a solution prepared by adding 5.98 g of ammonium iodide to 145 mL of water? Kb of NH3 is 1.8 × 10-5.

The equilibrium hydronium ion concentration of an initially 0.655 M solution of a monoprotic weak acid is M.The acid dissociation constant is At 25°C.What is the pH of this solution?

For which of the following equilibria does Kc correspond to the acid-ionization constant,Ka,of HC2O4-?

A weak base is titrated with a hydrochloric acid solution.What is the pH at the equivalence point?

Which of the following indicators is most suitable for the titration of a 25.00-mL sample of 0.140 M propionic acid,HC3H5O2,with strong base?

Carbonic acid,H2CO3,is a weak diprotic acid.In a 0.1 M solution of the acid,which of the following species is present in the largest amount?

What is the pOH of a solution prepared by adding 1.22 g of potassium nitrite to 155 mL of water? Ka of HNO2 is 4.5 × 10-4.

Given the following,what will be the approximate equilibrium pH of an aqueous solution of ammonium cyanide,NH4CN? NH4+ Ka = 5.69 x10-10 HCN Ka = 6.2 x10-10

What is the hydronium-ion concentration in a 0.018 M solution of carbonic acid,H2CO3? For carbonic acid,Ka1 = 4.2 × 10-7 and Ka2 = 4.8 × 10-11.

For which of the following equilibria does Kc correspond to the acid-dissociation constant,Ka,of H2PO4-?

In a 0.20 M solution of a diprotic acid H2A (Ka1 = 1.3 × 10-5 and Ka2 = 2.7 × 10-10 at 25°C),what is the equilibrium concentration of A2-?

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Filters

A 0.10 M aqueous solution of a weak acid HA has a pH of 5.00.What is the value of K_a for HA?

For which of the following equilibria does K_c correspond to an acid-ionization constant,K_a?

A 0.20 M solution of a weak monoprotic acid is 0.22 % ionized.What is the acid-ionization constant,K_a,for this acid?

Consider the titration of 300.0 mL of 0.457 M NH₃ (K_b = 1.8 ×10^-5)with 0.500 M HNO₃.After 150.0 mL of 0.500 M HNO₃ has been added,what is the pH of the solution?

A sample of ammonia (K_b = 1.8 × 10^-5)is titrated with 0.1 M HCl.At the equivalence point,what is the approximate pH of the solution?

What is the pOH of a solution prepared by adding 5.98 g of ammonium iodide to 145 mL of water? K_b of NH₃ is 1.8 × 10^-5.

For which of the following equilibria does K_c correspond to the acid-ionization constant,K_a,of HC₂O₄^-?

Which of the following indicators is most suitable for the titration of a 25.00-mL sample of 0.140 M propionic acid,HC₃H₅O₂,with strong base?

Carbonic acid,H₂CO₃,is a weak diprotic acid.In a 0.1 M solution of the acid,which of the following species is present in the largest amount?

What is the pOH of a solution prepared by adding 1.22 g of potassium nitrite to 155 mL of water? K_a of HNO₂ is 4.5 × 10^-4.

Given the following,what will be the approximate equilibrium pH of an aqueous solution of ammonium cyanide,NH₄CN? NH₄⁺ K_a = 5.69 x10^-10 HCN K_a = 6.2 x10^-10

What is the hydronium-ion concentration in a 0.018 M solution of carbonic acid,H₂CO₃? For carbonic acid,Ka₁ = 4.2 × 10^-7 and Ka₂ = 4.8 × 10^-11.

For which of the following equilibria does K_c correspond to the acid-dissociation constant,K_a,of H₂PO₄^-?

In a 0.20 M solution of a diprotic acid H₂A (Ka₁ = 1.3 × 10^-5 and Ka₂ = 2.7 × 10^-10 at 25°C),what is the equilibrium concentration of A^2-?