Question 1

The titration of a weak acid, HA ( K _a = 1.0×10^{- 4}), with NaOH requires 40.0 mL to reach the equivalence point. The pH after 20 mL is

Accepted Answer

The answer of The titration of a weak acid, HA...

Question 2

Which of the following titration curves listed below best represents a curve for the complete titration of the weakly basic dianion, sulfide, S^{2 -}, with a strong acid such as HCl as shown below in the net ionic equation? S^{2 -} (aq) + 2 HCl (aq)→H₂S (g) + 2 Cl^-

Accepted Answer

The titration of a weakly basic dianion with a strong acid produces a titration curve with an initial flat region representing the buffering capacity of the weakly basic dianion, followed by a steep rise in pH as the equivalence point approaches. Curve C best represents this type of titration curve.

Question 3

The pH at the equivalence point in the titration of 0.10 M NH₃ with 0.10 M HCl is:

Accepted Answer

At the equivalence point, NH4Cl is formed, which is a salt of a weak base (NH3) and a strong acid (HCl). The solution will be slightly acidic due to the hydrolysis of NH4+ ions.

Question 4

Exhibit 16-3 Consider the Titration curve below for the titration of a weak acid ,CH ₃COOH , with a strong base , NaOH, to answer the following question(s). CH ₃COOH + NaOH CH ₃COONa + H₂ O 
Refer to Exhibit 16-3. What approach listed below would be used to solve for the pH at the equivalence point on this titration curve?

Accepted Answer

The answer of Exhibit 16-3 Consider the Titration curve below...

Question 5

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

At the equivalence point of a titration between HCl and NaOH, the pH will be 7.0 because the reaction produces a neutral salt, NaCl, and water. In titration I, NH₃ is a weak base, so the pH at the equivalence point will be greater than 7.0. In titration III, CH₃COOH is a weak acid, so the pH at the equivalence point will be less than 7.0. Thus, only titration II will produce a pH of 7.0 at the equivalence point.

Question 6

Consider titrating a triprotic acid with standard NaOH as shown in the titration curve below.  What is the relationship between the first equivalence point and the third equivalence point in this titration curve?

Accepted Answer

The answer of Consider titrating a triprotic acid with standard...

Question 7

The titration of a weak acid, HA ( K _a = 1.0×10^{- 4}), with NaOH requires 40.0 mL to reach the equivalence point. In order to calculate the pH of the system after 20 mL of NaOH is added, the best strategy is to recognize that the system is

Accepted Answer

Since the weak acid is being titrated with NaOH, which is a strong base, the equivalence point will result in a basic solution. However, before the equivalence point, we still have a weak acid present. Therefore, the system is a buffer (a weak acid with its conjugate base) before the equivalence point. To calculate the pH after 20 mL of NaOH is added, we need to use the Henderson-Hasselbalch equation for a buffer solution.

Question 8

In the titration of 25.0 mL of 0.100 M acetic acid ( K _a = 1.8×10^{- 5}) with 0.100 M NaOH, the pH after adding 12.5 mL of titrant is:

Accepted Answer

First, we need to write a balanced chemical equation of the neutralization reaction between acetic acid and sodium hydroxide:

CH3COOH + NaOH → NaCH3COO + H2O

Next, we need to determine the amount of acetic acid present in the initial solution:

moles of acetic acid = volume of solution (in L) x concentration of acetic acid
moles of acetic acid = 0.025 L x 0.100 mol/L
moles of acetic acid = 0.0025 mol

Since the balanced chemical equation shows a 1:1 ratio between acetic acid and sodium hydroxide, the amount of sodium hydroxide added to the solution is also 0.0025 mol.

Now, we need to determine the amount of acetic acid and sodium hydroxide remaining after the neutralization reaction. At the equivalence point, all of the acetic acid will be converted to sodium acetate, so we can use the concentration and volume of the sodium hydroxide solution added to determine the concentration of sodium acetate:

moles of sodium hydroxide = volume of titrant (in L) x concentration of sodium hydroxide
0.0025 mol = 0.0125 L x 0.100 mol/L

The total volume of the solution at the equivalence point is the sum of the volumes of the acetic acid and sodium hydroxide solutions:

total volume at equivalence point = volume of acetic acid + volume of sodium hydroxide
total volume at equivalence point = 0.025 L + 0.0125 L
total volume at equivalence point = 0.0375 L

The concentration of sodium acetate at the equivalence point is:

0.0025 mol / 0.0375 L = 0.067 M

To determine the pH at the equivalence point, we need to calculate the pKa of acetic acid:

pKa = -log10(Ka)
pKa = -log10(1.8×10-5)
pKa = 4.75

At the halfway point of the titration, the concentration of acetic acid remaining is equal to the concentration of sodium acetate formed, so we can use the Henderson-Hasselbalch equation to determine the pH:

pH = pKa + log([A-]/[HA])

where [A-] is the concentration of sodium acetate and [HA] is the concentration of acetic acid.

At the halfway point of the titration, the concentrations of acetic acid and sodium acetate are equal, so:

[A-] = 0.0025 mol / 0.0375 L = 0.067 M
[HA] = 0.0025 mol / 0.0125 L = 0.200 M

pH = 4.75 + log(0.067/0.200)
pH = 4.74

Therefore, the pH after adding 12.5 mL of titrant is 4.74, which corresponds to choice D.

Question 9

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

The equivalence point in a titration of a weak acid with a strong base occurs when all of the acid has been neutralized by the base. At this point, a basic salt is formed. The pH at the equivalence point will be greater than 7.0 because the solution will be basic due to the excess hydroxide ions from the base. Therefore, the correct choice is E.

Question 10

A 20.0 mL sample of lactic acid (monoprotic with K _a = 1.37×10^{- 4}) requires 30.0 mL of 0.200 M NaOH for titration to the equivalence point. What is the concentration of the lactic acid solution?

Accepted Answer

The answer of A 20.0 mL sample of lactic acid...

Question 11

Which of the following titration curves listed below best represents a curve for the complete titration of citric acid, H₃C₆H₅O₇, a triprotic acid with a strong base such as NaOH?

Accepted Answer

The answer of Which of the following titration curves listed...

Question 12

The titration of a weak base ( K _b = 1.0×10^{- 4}) with HCl requires 40.0 mL to reach the equivalence point. In order to calculate the pH of the system after 20 mL of HCl is added, the best strategy is to recognize that the system is

Accepted Answer

At the equivalence point, all of the weak base has been neutralized by the strong acid, resulting in a solution containing only the conjugate acid of the weak base. Therefore, at the equivalence point, the solution is acidic with a pH less than 7.

However, before the equivalence point, when only 20.0 mL of the HCl has been added, the system is still a weak base and the addition of the HCl will create a buffer system. The weak base will react with the HCl to form its conjugate acid, which will then act as a buffer to resist changes in pH. Therefore, the best choice is C, a buffer.

Question 13

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

At the point of adding 25.0 mL of 0.100 M NaOH to the solution containing 0.100 mole of acetic acid in 50.0 mL, half of the acetic acid has been neutralized by the NaOH. This is the halfway point to the equivalence point in a titration, where the concentration of acetic acid equals the concentration of its conjugate base (acetate ion). At this point, the pH of the solution is equal to the pKa of acetic acid. The pKa can be calculated from the given Ka value (1.8×10^-5) as pKa = -log(Ka) = -log(1.8×10^-5) ≈ 4.74.

Question 14

Exhibit 16-3 Consider the Titration curve below for the titration of a weak acid ,CH ₃COOH , with a strong base , NaOH, to answer the following question(s). CH ₃COOH + NaOH CH ₃COONa + H₂ O 
Refer to Exhibit 16-3. What approach listed below would be used to determine the pH at point A of the solution?

Accepted Answer

The answer of Exhibit 16-3 Consider the Titration curve below...

Question 15

Exhibit 16-2 Consider titrating CHS1U1B13S1U1B0COOH with standard NaOH (delivered from the burette) to answer the following question(s).
-Refer to Exhibit 16-2. How would the pH be determined for the aqueous solution in the titration above at the equivalence point ?

Accepted Answer

At the equivalence point of a titration involving a weak acid and a strong base, the pH is determined by the resulting basic salt formed from the reaction, hence option D is correct.

Question 16

What is the pH of solution formed by adding 25.0 mL of 0.100 M HCl to 25.0 mL of 0.100 M pyridine (C₅H₅N, K _b = 1.8×10^{- 9})?

Accepted Answer

The first step is to write the balanced equation for the reaction between HCl and pyridine:

HCl + C5H5N -> C5H5NHCl

This reaction is an acid-base reaction where HCl is the acid and pyridine is the base. The pyridine will react with the H+ ions from HCl to form C5H5NH+ ions.

The next step is to calculate the initial moles of HCl and pyridine:

moles of HCl = 0.100 mol/L x 0.025 L = 0.0025 mol
moles of pyridine = 0.100 mol/L x 0.025 L = 0.0025 mol

Since the moles of HCl and pyridine are equal, the pyridine will be completely consumed in the reaction. This means that the moles of H+ formed will be equal to the moles of pyridine initially present:

moles of H+ = 0.0025 mol

Now we need to calculate the concentration of H+ ions in the solution. We know that the volume of the solution is 50.0 mL (25.0 mL HCl + 25.0 mL pyridine), so we can calculate the total moles of the solution:

moles of solution = 0.0025 mol H+ + 0.0025 mol pyridine = 0.0050 mol

Using the total volume of the solution, we can calculate the molarity of the H+ ions:

Molarity of H+ = moles of H+ / total volume of solution = 0.0050 mol / 0.050 L = 0.100 M

Finally, we can calculate the pH of the solution using the formula:

pH = -log[H+]

pH = -log(0.100) = 1 - (-1)log(0.100) = 1 + 1 = 2

Therefore, the answer is D) 3.28.

Question 17

What is the pH of the following solution? 20)0 mL of 0.50 M acetic acid ( K _a = 1.8×10^{- 5}) is added tO₅ .00 mL of 0.50 M NaOH.

Accepted Answer

The reaction between acetic acid and NaOH is a neutralization reaction, which produces sodium acetate and water. The pH of the solution will depend on the concentration of the sodium acetate, which is a weak base. The pKa of acetic acid is 4.74, so the pH of the solution will be greater than 4.74. The correct answer is A.

Question 18

The sharpest inflection point is observed in the titration of

Accepted Answer

The sharpest inflection point in a titration curve occurs when a strong acid is titrated with a strong base (or vice versa) due to the complete and immediate neutralization reaction. Among the options, 0.1 M HCl (a strong acid) with 0.10 M NaOH (a strong base) will show the sharpest inflection point.

Question 19

Which experiment listed below would provide a titration curve that resembles the titration shown below?

Accepted Answer

The answer of Which experiment listed below would provide a...

Question 20

Exhibit 16-2 Consider titrating CHS1U1B13S1U1B0COOH with standard NaOH (delivered from the burette) to answer the following question(s). -Refer to Exhibit 16-2. What compound(s) is(are) present in the region after the titration has begun but before the equivalence point? I. CH₃COOH II. NaOH III. CH₃COO^-Na⁺

Accepted Answer

Before the equivalence point, there is an excess of CH₃COOH present in the solution, as well as the initial addition of NaOH that has not yet reacted. Additionally, the reaction between the acid and base creates the compound CH₃COO^-Na⁺, which is a salt and therefore remains in solution. Therefore, options I and III are present before the equivalence point. Option II is not present as it has not yet been added to the solution.

Quiz 16: Reactions Between Acids and Bases

The titration of a weak acid, HA ( K _a = 1.0×10^{- 4}) , with NaOH requires 40.0 mL to reach the equivalence point. The pH after 20 mL is

Which of the following titration curves listed below best represents a curve for the complete titration of the weakly basic dianion, sulfide, S^{2 -}, with a strong acid such as HCl as shown below in the net ionic equation? S^{2 -} (aq) + 2 HCl (aq) →H₂S (g) + 2 Cl^-

The pH at the equivalence point in the titration of 0.10 M NH₃ with 0.10 M HCl is:

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)

Consider titrating a triprotic acid with standard NaOH as shown in the titration curve below. What is the relationship between the first equivalence point and the third equivalence point in this titration curve?

The titration of a weak acid, HA ( K _a = 1.0×10^{- 4}) , with NaOH requires 40.0 mL to reach the equivalence point. In order to calculate the pH of the system after 20 mL of NaOH is added, the best strategy is to recognize that the system is

In the titration of 25.0 mL of 0.100 M acetic acid ( K _a = 1.8×10^{- 5}) with 0.100 M NaOH, the pH after adding 12.5 mL of titrant is:

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

A 20.0 mL sample of lactic acid (monoprotic with K _a = 1.37×10^{- 4}) requires 30.0 mL of 0.200 M NaOH for titration to the equivalence point. What is the concentration of the lactic acid solution?

Which of the following titration curves listed below best represents a curve for the complete titration of citric acid, H₃C₆H₅O₇, a triprotic acid with a strong base such as NaOH?

The titration of a weak base ( K _b = 1.0×10^{- 4}) with HCl requires 40.0 mL to reach the equivalence point. In order to calculate the pH of the system after 20 mL of HCl is added, the best strategy is to recognize that the system is

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?

Exhibit 16-2 Consider titrating CH₃COOH with standard NaOH (delivered from the burette) to answer the following question(s) . -Refer to Exhibit 16-2. How would the pH be determined for the aqueous solution in the titration above at the equivalence point ?

What is the pH of solution formed by adding 25.0 mL of 0.100 M HCl to 25.0 mL of 0.100 M pyridine (C₅H₅N, K _b = 1.8×10^{- 9}) ?

What is the pH of the following solution? 20) 0 mL of 0.50 M acetic acid ( K _a = 1.8×10^{- 5}) is added tO₅ .00 mL of 0.50 M NaOH.

The sharpest inflection point is observed in the titration of

Which experiment listed below would provide a titration curve that resembles the titration shown below?

Quiz 16: Reactions Between Acids and Bases

The titration of a weak acid, HA ( K a = 1.0×10 - 4) , with NaOH requires 40.0 mL to reach the equivalence point. The pH after 20 mL is

Which of the following titration curves listed below best represents a curve for the complete titration of the weakly basic dianion, sulfide, S2 - , with a strong acid such as HCl as shown below in the net ionic equation? S2 - (aq) + 2 HCl (aq) →H2S (g) + 2 Cl -

The pH at the equivalence point in the titration of 0.10 M NH3 with 0.10 M HCl is:

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)

Consider titrating a triprotic acid with standard NaOH as shown in the titration curve below. What is the relationship between the first equivalence point and the third equivalence point in this titration curve?

The titration of a weak acid, HA ( K a = 1.0×10 - 4) , with NaOH requires 40.0 mL to reach the equivalence point. In order to calculate the pH of the system after 20 mL of NaOH is added, the best strategy is to recognize that the system is

In the titration of 25.0 mL of 0.100 M acetic acid ( K a = 1.8×10 - 5) with 0.100 M NaOH, the pH after adding 12.5 mL of titrant is:

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

A 20.0 mL sample of lactic acid (monoprotic with K a = 1.37×10 - 4) requires 30.0 mL of 0.200 M NaOH for titration to the equivalence point. What is the concentration of the lactic acid solution?

Which of the following titration curves listed below best represents a curve for the complete titration of citric acid, H3C6H5O7, a triprotic acid with a strong base such as NaOH?

The titration of a weak base ( K b = 1.0×10 - 4) with HCl requires 40.0 mL to reach the equivalence point. In order to calculate the pH of the system after 20 mL of HCl is added, the best strategy is to recognize that the system is

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?

Exhibit 16-2 Consider titrating CH3COOH with standard NaOH (delivered from the burette) to answer the following question(s) . -Refer to Exhibit 16-2. How would the pH be determined for the aqueous solution in the titration above at the equivalence point ?

What is the pH of solution formed by adding 25.0 mL of 0.100 M HCl to 25.0 mL of 0.100 M pyridine (C5H5N, K b = 1.8×10 - 9) ?

What is the pH of the following solution? 20) 0 mL of 0.50 M acetic acid ( K a = 1.8×10 - 5) is added tO5 .00 mL of 0.50 M NaOH.

The sharpest inflection point is observed in the titration of

Which experiment listed below would provide a titration curve that resembles the titration shown below?

Exhibit 16-2 Consider titrating CH3COOH with standard NaOH (delivered from the burette) to answer the following question(s) . -Refer to Exhibit 16-2. What compound(s) is(are) present in the region after the titration has begun but before the equivalence point? I. CH3COOH II. NaOH III. CH3COO - Na+

The titration of a weak acid, HA ( K _a = 1.0×10^{- 4}) , with NaOH requires 40.0 mL to reach the equivalence point. The pH after 20 mL is

Which of the following titration curves listed below best represents a curve for the complete titration of the weakly basic dianion, sulfide, S^{2 -}, with a strong acid such as HCl as shown below in the net ionic equation? S^{2 -} (aq) + 2 HCl (aq) →H₂S (g) + 2 Cl^-

The pH at the equivalence point in the titration of 0.10 M NH₃ with 0.10 M HCl is:

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)

The titration of a weak acid, HA ( K _a = 1.0×10^{- 4}) , with NaOH requires 40.0 mL to reach the equivalence point. In order to calculate the pH of the system after 20 mL of NaOH is added, the best strategy is to recognize that the system is

In the titration of 25.0 mL of 0.100 M acetic acid ( K _a = 1.8×10^{- 5}) with 0.100 M NaOH, the pH after adding 12.5 mL of titrant is:

A 20.0 mL sample of lactic acid (monoprotic with K _a = 1.37×10^{- 4}) requires 30.0 mL of 0.200 M NaOH for titration to the equivalence point. What is the concentration of the lactic acid solution?

Which of the following titration curves listed below best represents a curve for the complete titration of citric acid, H₃C₆H₅O₇, a triprotic acid with a strong base such as NaOH?

The titration of a weak base ( K _b = 1.0×10^{- 4}) with HCl requires 40.0 mL to reach the equivalence point. In order to calculate the pH of the system after 20 mL of HCl is added, the best strategy is to recognize that the system is

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?

Exhibit 16-2 Consider titrating CH₃COOH with standard NaOH (delivered from the burette) to answer the following question(s) . -Refer to Exhibit 16-2. How would the pH be determined for the aqueous solution in the titration above at the equivalence point ?

What is the pH of solution formed by adding 25.0 mL of 0.100 M HCl to 25.0 mL of 0.100 M pyridine (C₅H₅N, K _b = 1.8×10^{- 9}) ?

What is the pH of the following solution? 20) 0 mL of 0.50 M acetic acid ( K _a = 1.8×10^{- 5}) is added tO₅ .00 mL of 0.50 M NaOH.