Question 1

What is the hydronium-ion concentration of a solution formed by combining 400.mL of 0.21 M HNO3 with 600.mL of 0.10 M NaOH at 25°C?

Accepted Answer

A) 0.086 M 
B) 6.7 × 10-13 M 
C) 0.21 M 
D) 0.024 M 
E) 0.10 M 
A) 0.086 M 
B) 6.7 × 10-13 M 
C) 0.21 M 
D) 0.024 M 
E) 0.10 M

Question 2

What is the base-ionization equilibrium constant for an aqueous solution of ammonia,NH3?

Accepted Answer

A)    
B)    
C)    
D)    
E) none of these 
A)    
B)    
C)    
D)    
E) none of these

Question 3

What is the pH of a buffer made by combining 181 mL of 0.34 M NaC2H3O2 with 170 mL of 0.28 M HC2H3O2? The Ka of acetic acid is 1.75 × 10-5.

Accepted Answer

A) 4.88 
B) 4.64 
C) 5.93 
D) 4.83 
E) 5.38 
A) 4.88 
B) 4.64 
C) 5.93 
D) 4.83 
E) 5.38

Question 4

Which of the following statements is true concerning a 0.1 M solution of Na2S and a 0.1 M solution of NaHS? For H2S,Ka1 = 1.0 × 10-7 and Ka2 = 1.3 × 10-13.

Accepted Answer

A) Both solutions are neutral. 
B) The sodium hydrogen sulfide solution is the more basic. 
C) Both solutions have the same pH. 
D) The sodium sulfide solution is the more basic. 
E) Both the solutions are acidic. 
A) Both solutions are neutral. 
B) The sodium hydrogen sulfide solution is the more basic. 
C) Both solutions have the same pH. 
D) The sodium sulfide solution is the more basic. 
E) Both the solutions are acidic.

Question 5

What is the equilibrium concentration of ammonium ion in a 0.33 M solution of ammonia (NH3,Kb = 1.8 × 10-5)at 25oC?

Accepted Answer

A) 3.0 × 10-14 M 
B) 4.1 × 10-12 M 
C) 2.4 × 10-3 M 
D) 7.4 × 10-3 M 
E) 3.3 × 10-1 M 
A) 3.0 × 10-14 M 
B) 4.1 × 10-12 M 
C) 2.4 × 10-3 M 
D) 7.4 × 10-3 M 
E) 3.3 × 10-1 M

Question 6

At a temperature of 25°C an initally 0.011 M solution of a weak monoprotic acid is 2.9 % ionized once equilibrium is established.What is the acid-ionization constant,Ka,for this acid? (assume Ca/Ka ≥ 102)

Accepted Answer

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

Question 7

What is the pH of a 0.24 M solution of sodium propionate,NaC3H5O2,at 25°C? (For propionic acid,HC3H5O2,Ka = 1.3 × 10-5 at 25°C.)

Accepted Answer

A) 6.34 
B) 4.87 
C) 11.10 
D) 7.66 
E) 9.13 
A) 6.34 
B) 4.87 
C) 11.10 
D) 7.66 
E) 9.13

Question 8

A 75.0-mL sample of 0.0500 M HCN (Ka = 6.2 ×10-10)is titrated with 0.370 M NaOH.What is [H+] in the solution after 3.0 mL of 0.370 M NaOH has been added?

Accepted Answer

A) 6.8 × 10-6 M 
B) 2.4 M 
C) 1.5 × 10-9 M 
D) 1.0 × 10-7 M 
E) none of these 
A) 6.8 × 10-6 M 
B) 2.4 M 
C) 1.5 × 10-9 M 
D) 1.0 × 10-7 M 
E) none of these

Question 9

What molar ratio of acetic acid to sodium acetate is required to create a buffer solution having a pH of 4.93 at 25°C? Ka for HC2H3O2 is 1.8 × 10-5.

Accepted Answer

A) ​0.65 
B) 1.5 
C) 0.54 
D) 2.0 
E) 3.3 
A) ​0.65 
B) 1.5 
C) 0.54 
D) 2.0 
E) 3.3

Question 10

What will happen if a small amount of hydrochloric acid is added to a 0.1 M solution of HF?

Accepted Answer

A) The percent ionization of HF will decrease. 
B) Ka for HF will increase. 
C) Ka for HF will decrease. 
D) The percent ionization of HF will remain unchanged. 
E) The percent ionization of HF will increase. 
A) The percent ionization of HF will decrease. 
B) Ka for HF will increase. 
C) Ka for HF will decrease. 
D) The percent ionization of HF will remain unchanged. 
E) The percent ionization of HF will increase.

Question 11

What is the hydroxide-ion concentration of a 0.150 M oxalic acid,H2C2O4,solution? For oxalic acid,Ka1 = 5.6 × 10-2 and Ka2 = 5.1 × 10-5.

Accepted Answer

A) 3.6 × 10-12 M 
B) 1.1 × 10-13 M 
C) 2.7 × 10-3 M 
D) 1.5 × 10-13 M 
E) 1.0 × 10-7 M 
A) 3.6 × 10-12 M 
B) 1.1 × 10-13 M 
C) 2.7 × 10-3 M 
D) 1.5 × 10-13 M 
E) 1.0 × 10-7 M

Question 12

What is the pH of the solution if 0.089 g of sodium fluoride is added to 135.0 mL of a 0.077 M HF solution? Ka for HF is 6.8 × 10-4.

Accepted Answer

A) 2.56 
B) 5.90 
C) 2.53 
D) 2.16 
E) 4.98 
A) 2.56 
B) 5.90 
C) 2.53 
D) 2.16 
E) 4.98

Question 13

The following titration curve depicts the titration of a weak base with a strong acid.Which of the labeled points is the equivalence point.

Accepted Answer

A) III only 
B) II only 
C) I only 
D) V only 
E) IV only 
A) III only 
B) II only 
C) I only 
D) V only 
E) IV only

Question 14

A solution of aniline (C6H5NH2,Kb = 4.2 × 10-10)has a pH of 8.56 at 25oC.What was the initial concentration of aniline?

Accepted Answer

A) 2.8 × 10-9 M 
B) 2.1 × 10-8 M 
C) 3.2 × 10-2 M 
D) 4.2 × 10-10 M 
E) 3.6 × 10-6 M 
A) 2.8 × 10-9 M 
B) 2.1 × 10-8 M 
C) 3.2 × 10-2 M 
D) 4.2 × 10-10 M 
E) 3.6 × 10-6 M

Question 15

What is the hydroxide-ion concentration in a 0.16 M solution of Na2CO3? For carbonic acid,Ka1 = 4.2 × 10-7 and Ka2 = 4.8 × 10-11.(Kw = 1.0 × 10-14)

Accepted Answer

A) 5.8 × 10-3 M 
B) 2.0 × 10-4 M 
C) 6.2 × 10-5 M 
D) 4.5 × 10-9 M 
E) 2.8 × 10-6 M 
A) 5.8 × 10-3 M 
B) 2.0 × 10-4 M 
C) 6.2 × 10-5 M 
D) 4.5 × 10-9 M 
E) 2.8 × 10-6 M

Question 16

A 8.42-g sample of homogentisic acid,a weak organic acid having Ka = 4.0 × 10-5,is dissolved in 35.00 mL of water and its pH is measured to be 2.122.What is the molar mass of homogentisic acid?

Accepted Answer

A) 168 g/mol 
B) 1110 g/mol 
C) 1.43 g/mol 
D) 5.88 g/mol 
E) 240 g/mol 
A) 168 g/mol 
B) 1110 g/mol 
C) 1.43 g/mol 
D) 5.88 g/mol 
E) 240 g/mol

Question 17

Which of the following salts is most likely to form an aqueous solution having the pH shown in the figure below?

Accepted Answer

A) KCl 
B) Zn(NO3)2 
C) NaCN 
D) NH4Cl 
E) LiBr 
A) KCl 
B) Zn(NO3)2 
C) NaCN 
D) NH4Cl 
E) LiBr

Question 18

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

Question 19

A 8.0 × 10-3 M solution of acetic acid,HC2H3O2,is 4.7% ionized at 25°C.In a 8.0 × 10-4 M solution,the percentage of ionization would be

Accepted Answer

A) 100%. 
B) 4.7%. 
D) the same. 
E) zero. 
A) 100%. 
B) 4.7%. 
D) the same. 
E) zero.

Question 20

What is the pOH of a 0.17 M solution of pyridine (Kb = 1.4 × 10-9)at 25°C?

Accepted Answer

A) 1.54 
B) 4.04 
C) 8.85 
D) 4.81 
E) 11.08 
A) 1.54 
B) 4.04 
C) 8.85 
D) 4.81 
E) 11.08

Exam 16: Acid-Base Equilibria

What is the hydronium-ion concentration of a solution formed by combining 400.mL of 0.21 M HNO3 with 600.mL of 0.10 M NaOH at 25°C?

What is the base-ionization equilibrium constant for an aqueous solution of ammonia,NH3?

What is the pH of a buffer made by combining 181 mL of 0.34 M NaC2H3O2 with 170 mL of 0.28 M HC2H3O2? The Ka of acetic acid is 1.75 × 10-5.

Which of the following statements is true concerning a 0.1 M solution of Na2S and a 0.1 M solution of NaHS? For H2S,Ka1 = 1.0 × 10-7 and Ka2 = 1.3 × 10-13.

What is the equilibrium concentration of ammonium ion in a 0.33 M solution of ammonia (NH3,Kb = 1.8 × 10-5)at 25oC?

At a temperature of 25°C an initally 0.011 M solution of a weak monoprotic acid is 2.9 % ionized once equilibrium is established.What is the acid-ionization constant,Ka,for this acid? (assume Ca/Ka ≥ 102)

What is the pH of a 0.24 M solution of sodium propionate,NaC3H5O2,at 25°C? (For propionic acid,HC3H5O2,Ka = 1.3 × 10-5 at 25°C.)

A 75.0-mL sample of 0.0500 M HCN (Ka = 6.2 ×10-10)is titrated with 0.370 M NaOH.What is [H+] in the solution after 3.0 mL of 0.370 M NaOH has been added?

What molar ratio of acetic acid to sodium acetate is required to create a buffer solution having a pH of 4.93 at 25°C? Ka for HC2H3O2 is 1.8 × 10-5.

What will happen if a small amount of hydrochloric acid is added to a 0.1 M solution of HF?

What is the hydroxide-ion concentration of a 0.150 M oxalic acid,H2C2O4,solution? For oxalic acid,Ka1 = 5.6 × 10-2 and Ka2 = 5.1 × 10-5.

What is the pH of the solution if 0.089 g of sodium fluoride is added to 135.0 mL of a 0.077 M HF solution? Ka for HF is 6.8 × 10-4.

The following titration curve depicts the titration of a weak base with a strong acid.Which of the labeled points is the equivalence point.

A solution of aniline (C6H5NH2,Kb = 4.2 × 10-10)has a pH of 8.56 at 25oC.What was the initial concentration of aniline?

What is the hydroxide-ion concentration in a 0.16 M solution of Na2CO3? For carbonic acid,Ka1 = 4.2 × 10-7 and Ka2 = 4.8 × 10-11.(Kw = 1.0 × 10-14)

A 8.42-g sample of homogentisic acid,a weak organic acid having Ka = 4.0 × 10-5,is dissolved in 35.00 mL of water and its pH is measured to be 2.122.What is the molar mass of homogentisic acid?

Which of the following salts is most likely to form an aqueous solution having the pH shown in the figure below?

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

A 8.0 × 10-3 M solution of acetic acid,HC2H3O2,is 4.7% ionized at 25°C.In a 8.0 × 10-4 M solution,the percentage of ionization would be

What is the pOH of a 0.17 M solution of pyridine (Kb = 1.4 × 10-9)at 25°C?

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What is the hydronium-ion concentration of a solution formed by combining 400.mL of 0.21 M HNO₃ with 600.mL of 0.10 M NaOH at 25°C?

What is the base-ionization equilibrium constant for an aqueous solution of ammonia,NH₃?

What is the pH of a buffer made by combining 181 mL of 0.34 M NaC₂H₃O₂ with 170 mL of 0.28 M HC₂H₃O₂? The K_a of acetic acid is 1.75 × 10^-5.

Which of the following statements is true concerning a 0.1 M solution of Na₂S and a 0.1 M solution of NaHS? For H₂S,Ka₁ = 1.0 × 10^-7 and Ka₂ = 1.3 × 10^-13.

What is the equilibrium concentration of ammonium ion in a 0.33 M solution of ammonia (NH₃,K_b = 1.8 × 10^-5)at 25^oC?

At a temperature of 25°C an initally 0.011 M solution of a weak monoprotic acid is 2.9 % ionized once equilibrium is established.What is the acid-ionization constant,K_a,for this acid? (assume C_a/K_a≥ 10²)

What is the pH of a 0.24 M solution of sodium propionate,NaC₃H₅O₂,at 25°C? (For propionic acid,HC₃H₅O₂,K_a = 1.3 × 10^-5 at 25°C.)

A 75.0-mL sample of 0.0500 M HCN (K_a = 6.2 ×10^-10)is titrated with 0.370 M NaOH.What is [H⁺] in the solution after 3.0 mL of 0.370 M NaOH has been added?

What molar ratio of acetic acid to sodium acetate is required to create a buffer solution having a pH of 4.93 at 25°C? K_a for HC₂H₃O₂ is 1.8 × 10^-5.

What is the hydroxide-ion concentration of a 0.150 M oxalic acid,H₂C₂O₄,solution? For oxalic acid,Ka₁ = 5.6 × 10^-2 and Ka₂ = 5.1 × 10^-5.

What is the pH of the solution if 0.089 g of sodium fluoride is added to 135.0 mL of a 0.077 M HF solution? K_a for HF is 6.8 × 10^-4.

A solution of aniline (C₆H₅NH₂,K_b = 4.2 × 10^-10)has a pH of 8.56 at 25^oC.What was the initial concentration of aniline?

What is the hydroxide-ion concentration in a 0.16 M solution of Na₂CO₃? For carbonic acid,Ka₁ = 4.2 × 10^-7 and Ka₂ = 4.8 × 10^-11.(K_w = 1.0 × 10^-14)

A 8.42-g sample of homogentisic acid,a weak organic acid having K_a = 4.0 × 10^-5,is dissolved in 35.00 mL of water and its pH is measured to be 2.122.What is the molar mass of homogentisic acid?

A 8.0 × 10^-3 M solution of acetic acid,HC₂H₃O₂,is 4.7% ionized at 25°C.In a 8.0 × 10^-4 M solution,the percentage of ionization would be

What is the pOH of a 0.17 M solution of pyridine (K_b = 1.4 × 10^-9)at 25°C?