Question 1

In the titration of 25.0 mL of a solution of a weak acid HX with 0.250 M NaOH, the pH = 4.50 after the addition of 5.0 mL of the NaOH solution. The equivalence point occurs when 30.4 mL of the NaOH solution has been added. What is the ionization constant ( K a) of HX?

Accepted Answer

A)  1.4×10 - 5 
B)  3.2×10 - 5 
C)  6.2×10 - 6 
D)  3.2×10 - 10 
E)  7.2×10 - 10

Question 2

Carbonic acid is a diprotic acid with K al = 4.3×10 - 7 and K a2 = 5.6×10 - 11. Estimate the pH of a solution of sodium hydrogen carbonate.

Accepted Answer

A)  pH = 2 
B)  pH = 4 
C)  pH = 6 
D)  pH = 8 
E)  pH = 10

Question 3

Solutions are made by combining equal amounts of the following. Which is a buffer?

Accepted Answer

A)  0.1 M HCl + 0.1 M Cl -  
B)  0.1 M HF + 0.1 M Na+ 
C)  0.1 M HF + 0.1 M NaOH 
D)  0.1 M NaF + 0.05 M HF 
E)  0.1 M NaF + 0.05 M Na+

Question 4

Exhibit 16-1 Consider the equilibrium reaction below to answer the following question(s). HNO₂ + H₂ O  H₃O + + NO₂ 1 - K a (HNO₂ ) = 4.5 10 - 4
-Refer to Exhibit 16-1. What is the concentration of nitrite ion, NO₂ - , present at equilibrium if 0.100 moles of HCl are added to 0.200 moles of HNO₂ to form one-liter of solution?

Accepted Answer

A)  [NO2 - ] = 9.00×10 - 4 M 
B)  [NO2 - ] = 2.12×10 - 3 M 
C)  [NO2 - ] = 9.49×10 - 3 M 
D)  [NO2 - ] = 0.100 M 
E)  [NO2 - ] = 0.200 M

Question 5

Which of the following salts, each having very limited solubility in water, would dissolve to a greater extent upon acidifying the solution?
I. Ag2S
II. Mg3(PO4)2
III. AgBr

Accepted Answer

A)  I only 
B)  II only 
C)  I and II 
D)  All of these 
E)  None of these

Question 6

Oxalic acid is diprotic with p K al = 1.23 and p K a2 = 4.19. What is p K b for the hydrogen oxalate ion?

Accepted Answer

A)  1.23 
B)  4.19 
C)  7.00 
D)  9.81 
E)  12.77

Question 7

Which of the following titrations would produce a pH equal to 7.0 at the equivalence point?
I. Titrating NH3 with standard HCl (delivered from the burette)
II. Titrating HCl with standard NaOH (delivered from the burette)
III. Titrating CH3COOH with standard NaOH (delivered from the burette)

Accepted Answer

A)  I only 
B)  II only 
C)  III only 
D)  II and III 
E)  All of these

Question 8

A 0.10 M solution of hydrazine (N2H4, K b = 1.7×10 - 6) containing an unknown concentration of hydrazine hydrochloride (N2H5Cl) has a pH of 7.50. What is the concentration of N2H5Cl in the solution?

Accepted Answer

A)  1.26 M 
B)  0.54 M 
C)  5.8 M 
D)  0.10 M 
E)  0.72 M

Question 9

Which of the following general combinations of substances form an acid-base buffer when added to water?

Accepted Answer

A)  a strong acid and the sodium salt of its conjugate base 
B)  a strong base and the chloride salt of its conjugate acid 
C)  a weak acid and the sodium salt of its conjugate base 
D)  a weak acid 
E)  a weak base and a strong base

Question 10

Consider a buffer solution containing a weak acid, HX, and a salt of the weak acid's conjugate base, NaX. Under what conditions is the pH greater than the p K a of the weak acid?

Accepted Answer

A)  When the p K a equals 7.0. 
B)  When [HX] > [NaX]. 
C)  When [HX] < [NaX]. 
D)  When [HX] = [NaX]. 
E)  When there is no NaX present.

Question 11

A sample of acetic acid (approximately 0.001 M, K a = 1.8×10 - 5) is titrated with 0.00993 M NaOH. What indicator should be used?

Accepted Answer

A)  thymol blue (p K In = 1.65) 
B)  methyl orange (p K In = 3.46) 
C)  methyl red (p K In = 5.00) 
D)  bromthymol blue (p K In = 7.30) 
E)  phenolphthalein (p K In = 8.7)

Question 12

Consider the two buffer solutions prepared below:
Solution A:
[HA] = 0.15 M and [A - ] = 0.25 M Solution B:
[HA] = 1.50 M and [A - ] = 2.50 M Which statement below is true regarding the pH and buffering capacity of these two solutions?

Accepted Answer

A)  Solution A will have a greater pH value and a smaller buffering capacity. 
B)  Solution B will have a greater pH value and a smaller buffering capacity. 
C)  Solution B will have a greater pH value and a larger buffering capacity. 
D)  The pH of both solutions will be identical but Solution A will have a larger buffering capacity. 
E)  The pH of both solutions will be identical but Solution B will have a larger buffering capacity.

Question 13

Calculate the pH of a buffer prepared by dissolving 0.10 mol of NH4Cl in 1.00 L of 0.15 M NH3. K b = 1.8×10 - 5 for NH3.

Accepted Answer

A)  9.43 
B)  4.56 
C)  11.34 
D)  2.72 
E)  4.74

Question 14

What is the volume of 0.0175 M Ba(OH)2 required to neutralize 10.0 mL of 0.0300 M HCl?

Accepted Answer

A)  10.0 mL 
B)  34.2 mL 
C)  17.1 mL 
D)  8.6 mL 
E)  4.3 mL

Question 15

A buffer was prepared such that the pH was 5.20. If the solution contains 0.400 moles of acetic acid (CH3COOH) per liter, what is the concentration of the acetate ion (CH3COO - ) in this solution?
The p K a for acetic acid is 4.74.

Accepted Answer

A)  0.40 M 
B)  0.14 M 
C)  4.2×10 - 3 M 
D)  6.3×10 - 6 M 
E)  1.1 M

Question 16

Calculate the pH of a solution formed when 1.5 L oF4.5×10 - 3 M HCl is mixed witH₂ .0 L of 3.0×10 - 3 M HNO3.

Accepted Answer

A)  3.67 
B)  3.74 
C)  2.25 
D)  3.16 
E)  2.44

Question 17

Which of the following mixtures would not be suitable for preparing a buffer solution?

Accepted Answer

A)  NH4Cl and NH3 
B)  HNO3 and NaNO3 
C)  HF and KF 
D)  C6H5COOH (Benzoic acid) and C6H5COO - Na+ 
E)  CH3COOH and CH3COO - Na+

Question 18

A sample of 0.100 mole of acetic acid ( K a = 1.8×10 - 5) in 50.0 mL of solution is titrated with standard 0.100 M NaOH. What is the pH in the titration flask after addition of 25.0 mL of the base?

Accepted Answer

A)  2.88 
B)  3.18 
C)  2.60 
D)  4.74 
E)  11.40

Question 19

Consider the titration of a weak acid with a strong base . Which statement below is true regarding the equivalence point in this titration?

Accepted Answer

A)  It occurs at a pH = 7.0 because the acid has been neutralized. 
B)  It occurs at a pH less than 7.0 because an acidic salt is formed. 
C)  It occurs at a pH less than 7.0 because a basic salt is formed. 
D)  It occurs at a pH greater than 7.0 because an acidic salt is formed. 
E)  It occurs at a pH greater than 7.0 because a basic salt is formed.

Question 20

What volume of 0.200 M H₂ SO₄is required to neutralize 50.0 mL of 0.100 M NaOH?
Assume the chemical equation is:
H₂ SO₄(aq) + 2 NaOH (aq) Na2 SO₄(aq) + 2 H₂ O (  )

Accepted Answer

A)  50.0 mL 
B)  25.0 mL 
C)  100 mL 
D)  12.5 mL 
E)  6.25 mL

Exam 16: Reactions Between Acids and Bases

In the titration of 25.0 mL of a solution of a weak acid HX with 0.250 M NaOH, the pH = 4.50 after the addition of 5.0 mL of the NaOH solution. The equivalence point occurs when 30.4 mL of the NaOH solution has been added. What is the ionization constant ( K _a) of HX?

Carbonic acid is a diprotic acid with K _al = 4.3×10^{- 7} and K _a2 = 5.6×10^{- 11}. Estimate the pH of a solution of sodium hydrogen carbonate.

Solutions are made by combining equal amounts of the following. Which is a buffer?

Which of the following salts, each having very limited solubility in water, would dissolve to a greater extent upon acidifying the solution? I. Ag₂S II. Mg₃(PO₄) ₂ III. AgBr

Oxalic acid is diprotic with p K _al = 1.23 and p K _a2 = 4.19. What is p K _b for the hydrogen oxalate ion?

Which of the following titrations would produce a pH equal to 7.0 at the equivalence point? I. Titrating NH₃ with standard HCl (delivered from the burette) II. Titrating HCl with standard NaOH (delivered from the burette) III. Titrating CH₃COOH with standard NaOH (delivered from the burette)

A 0.10 M solution of hydrazine (N₂H₄, K _b = 1.7×10^{- 6}) containing an unknown concentration of hydrazine hydrochloride (N₂H₅Cl) has a pH of 7.50. What is the concentration of N₂H₅Cl in the solution?

Which of the following general combinations of substances form an acid-base buffer when added to water?

Consider a buffer solution containing a weak acid, HX, and a salt of the weak acid's conjugate base, NaX. Under what conditions is the pH greater than the p K _a of the weak acid?

A sample of acetic acid (approximately 0.001 M, K _a = 1.8×10^{- 5}) is titrated with 0.00993 M NaOH. What indicator should be used?

Consider the two buffer solutions prepared below: Solution A: [HA] = 0.15 M and [A^-] = 0.25 M Solution B: [HA] = 1.50 M and [A^-] = 2.50 M Which statement below is true regarding the pH and buffering capacity of these two solutions?

Calculate the pH of a buffer prepared by dissolving 0.10 mol of NH₄Cl in 1.00 L of 0.15 M NH₃. K _b = 1.8×10^{- 5} for NH₃.

What is the volume of 0.0175 M Ba(OH) ₂ required to neutralize 10.0 mL of 0.0300 M HCl?

A buffer was prepared such that the pH was 5.20. If the solution contains 0.400 moles of acetic acid (CH₃COOH) per liter, what is the concentration of the acetate ion (CH₃COO^-) in this solution? The p K _a for acetic acid is 4.74.

Calculate the pH of a solution formed when 1.5 L oF₄.5×10^{- 3} M HCl is mixed witH₂ .0 L of 3.0×10^{- 3} M HNO₃.

Which of the following mixtures would not be suitable for preparing a buffer solution?

A sample of 0.100 mole of acetic acid ( K _a = 1.8×10^{- 5}) in 50.0 mL of solution is titrated with standard 0.100 M NaOH. What is the pH in the titration flask after addition of 25.0 mL of the base?

Consider the titration of a weak acid with a strong base . Which statement below is true regarding the equivalence point in this titration?

What volume of 0.200 M H₂ SO₄is required to neutralize 50.0 mL of 0.100 M NaOH? Assume the chemical equation is: H₂ SO₄(aq) + 2 NaOH (aq) Na₂ SO₄(aq) + 2 H₂ O ( )

Exam 16: Reactions Between Acids and Bases

In the titration of 25.0 mL of a solution of a weak acid HX with 0.250 M NaOH, the pH = 4.50 after the addition of 5.0 mL of the NaOH solution. The equivalence point occurs when 30.4 mL of the NaOH solution has been added. What is the ionization constant ( K a) of HX?

Carbonic acid is a diprotic acid with K al = 4.3×10 - 7 and K a2 = 5.6×10 - 11. Estimate the pH of a solution of sodium hydrogen carbonate.

Solutions are made by combining equal amounts of the following. Which is a buffer?

Which of the following salts, each having very limited solubility in water, would dissolve to a greater extent upon acidifying the solution? I. Ag2S II. Mg3(PO4) 2 III. AgBr

Oxalic acid is diprotic with p K al = 1.23 and p K a2 = 4.19. What is p K b for the hydrogen oxalate ion?

Which of the following titrations would produce a pH equal to 7.0 at the equivalence point? I. Titrating NH3 with standard HCl (delivered from the burette) II. Titrating HCl with standard NaOH (delivered from the burette) III. Titrating CH3COOH with standard NaOH (delivered from the burette)

A 0.10 M solution of hydrazine (N2H4, K b = 1.7×10 - 6) containing an unknown concentration of hydrazine hydrochloride (N2H5Cl) has a pH of 7.50. What is the concentration of N2H5Cl in the solution?

Which of the following general combinations of substances form an acid-base buffer when added to water?

Consider a buffer solution containing a weak acid, HX, and a salt of the weak acid's conjugate base, NaX. Under what conditions is the pH greater than the p K a of the weak acid?

A sample of acetic acid (approximately 0.001 M, K a = 1.8×10 - 5) is titrated with 0.00993 M NaOH. What indicator should be used?

Consider the two buffer solutions prepared below: Solution A: [HA] = 0.15 M and [A - ] = 0.25 M Solution B: [HA] = 1.50 M and [A - ] = 2.50 M Which statement below is true regarding the pH and buffering capacity of these two solutions?

Calculate the pH of a buffer prepared by dissolving 0.10 mol of NH4Cl in 1.00 L of 0.15 M NH3. K b = 1.8×10 - 5 for NH3.

What is the volume of 0.0175 M Ba(OH) 2 required to neutralize 10.0 mL of 0.0300 M HCl?

A buffer was prepared such that the pH was 5.20. If the solution contains 0.400 moles of acetic acid (CH3COOH) per liter, what is the concentration of the acetate ion (CH3COO - ) in this solution? The p K a for acetic acid is 4.74.

Calculate the pH of a solution formed when 1.5 L oF4.5×10 - 3 M HCl is mixed witH₂ .0 L of 3.0×10 - 3 M HNO3.

Which of the following mixtures would not be suitable for preparing a buffer solution?

A sample of 0.100 mole of acetic acid ( K a = 1.8×10 - 5) in 50.0 mL of solution is titrated with standard 0.100 M NaOH. What is the pH in the titration flask after addition of 25.0 mL of the base?

Consider the titration of a weak acid with a strong base . Which statement below is true regarding the equivalence point in this titration?

What volume of 0.200 M H₂ SO₄is required to neutralize 50.0 mL of 0.100 M NaOH? Assume the chemical equation is: H₂ SO₄(aq) + 2 NaOH (aq) Na2 SO₄(aq) + 2 H₂ O ( )

In the titration of 25.0 mL of a solution of a weak acid HX with 0.250 M NaOH, the pH = 4.50 after the addition of 5.0 mL of the NaOH solution. The equivalence point occurs when 30.4 mL of the NaOH solution has been added. What is the ionization constant ( K _a) of HX?

Carbonic acid is a diprotic acid with K _al = 4.3×10^{- 7} and K _a2 = 5.6×10^{- 11}. Estimate the pH of a solution of sodium hydrogen carbonate.

Which of the following salts, each having very limited solubility in water, would dissolve to a greater extent upon acidifying the solution? I. Ag₂S II. Mg₃(PO₄) ₂ III. AgBr

Oxalic acid is diprotic with p K _al = 1.23 and p K _a2 = 4.19. What is p K _b for the hydrogen oxalate ion?

Which of the following titrations would produce a pH equal to 7.0 at the equivalence point? I. Titrating NH₃ with standard HCl (delivered from the burette) II. Titrating HCl with standard NaOH (delivered from the burette) III. Titrating CH₃COOH with standard NaOH (delivered from the burette)

A 0.10 M solution of hydrazine (N₂H₄, K _b = 1.7×10^{- 6}) containing an unknown concentration of hydrazine hydrochloride (N₂H₅Cl) has a pH of 7.50. What is the concentration of N₂H₅Cl in the solution?

Consider a buffer solution containing a weak acid, HX, and a salt of the weak acid's conjugate base, NaX. Under what conditions is the pH greater than the p K _a of the weak acid?

A sample of acetic acid (approximately 0.001 M, K _a = 1.8×10^{- 5}) is titrated with 0.00993 M NaOH. What indicator should be used?

Consider the two buffer solutions prepared below: Solution A: [HA] = 0.15 M and [A^-] = 0.25 M Solution B: [HA] = 1.50 M and [A^-] = 2.50 M Which statement below is true regarding the pH and buffering capacity of these two solutions?

Calculate the pH of a buffer prepared by dissolving 0.10 mol of NH₄Cl in 1.00 L of 0.15 M NH₃. K _b = 1.8×10^{- 5} for NH₃.

What is the volume of 0.0175 M Ba(OH) ₂ required to neutralize 10.0 mL of 0.0300 M HCl?

A buffer was prepared such that the pH was 5.20. If the solution contains 0.400 moles of acetic acid (CH₃COOH) per liter, what is the concentration of the acetate ion (CH₃COO^-) in this solution? The p K _a for acetic acid is 4.74.

Calculate the pH of a solution formed when 1.5 L oF₄.5×10^{- 3} M HCl is mixed witH₂ .0 L of 3.0×10^{- 3} M HNO₃.

A sample of 0.100 mole of acetic acid ( K _a = 1.8×10^{- 5}) in 50.0 mL of solution is titrated with standard 0.100 M NaOH. What is the pH in the titration flask after addition of 25.0 mL of the base?

What volume of 0.200 M H₂ SO₄is required to neutralize 50.0 mL of 0.100 M NaOH? Assume the chemical equation is: H₂ SO₄(aq) + 2 NaOH (aq) Na₂ SO₄(aq) + 2 H₂ O ( )