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AP Chemistry Practice Quiz: Acid-Base Titrations

Written by AP Content Team, Verified for 2026 AP Exams, Last updated: May 2026

Test your understanding with short quizzes. This quiz has 12 questions to check your progress.

Question 1 of 12

What are the standard axes on a typical acid-base titration curve used to summarize the results of the reaction?

All Questions (12)

What are the standard axes on a typical acid-base titration curve used to summarize the results of the reaction?

A) pH vs. volume of titrant added

B) Concentration of analyte vs. time

C) Temperature vs. volume of titrant added

D) Moles of acid vs. moles of base

Correct Answer: A

According to the provided content, a titration curve is a plot of 'pH vs. titrant volume' and is useful for summarizing results from a controlled acid-base reaction.

For the titration of a monoprotic acid, what is the defining characteristic of the equivalence point?

A) The pH of the solution is exactly 7.0.

B) The volume of titrant added is equal to the initial volume of the analyte.

C) The moles of titrant added are equal to the initial moles of analyte.

D) The concentration of the acid equals the concentration of its conjugate base.

Correct Answer: C

The provided content states that 'At the equivalence point for monoprotic titrations, moles of titrant added equal the original moles of analyte'.

When titrating a weak acid with a strong base, the pH at the equivalence point is observed to be basic. What is the primary reason for this?

A) The strong base titrant is in excess at the equivalence point.

B) The conjugate base of the weak acid reacts with water, producing OH⁻ ions.

C) The autoionization of water is suppressed by the presence of the salt.

D) The weak acid does not fully dissociate, leaving the solution basic.

Correct Answer: B

The content explains that for weak acid titrations, 'the conjugate base...present at the equivalence point hydrolyzes water, resulting in a basic...pH.' This hydrolysis reaction produces hydroxide ions (OH⁻).

In the titration curve of a weak acid, the point where the pH of the solution is equal to the pKa of the acid is known as the:

A) Equivalence point

B) Half-equivalence point

C) Starting point

D) Buffer point

Correct Answer: B

The content specifies that 'For weak acid/base titrations, the half-equivalence point occurs when [HA] = [A-]. At this point, pH = pKa'.

An analysis of a titration curve reveals two distinct equivalence points. What can be inferred about the analyte that was titrated?

A) The analyte is a strong acid.

B) The analyte is a polyprotic acid.

C) The titration was performed incorrectly.

D) The analyte is a monoprotic acid.

Correct Answer: B

As stated in the content, 'Titration curves for polyprotic acids can determine the number of acidic protons'. Each equivalence point corresponds to the neutralization of one acidic proton.

During a titration of a weak monoprotic acid, the equivalence point is reached after the addition of 30.0 mL of a strong base titrant. At what volume of added titrant is the concentration of the weak acid equal to the concentration of its conjugate base?

A) 0.0 mL

B) 15.0 mL

C) 30.0 mL

D) 45.0 mL

Correct Answer: B

The half-equivalence point is the point where [HA] = [A-]. This occurs at half the volume required to reach the equivalence point. Therefore, the volume is 30.0 mL / 2 = 15.0 mL.

Which statement accurately describes a key difference between the titration of a strong acid with a strong base and the titration of a weak acid with a strong base?

A) The pH at the equivalence point is neutral for the weak acid titration and basic for the strong acid titration.

B) The pH at the equivalence point is neutral for the strong acid titration and basic for the weak acid titration.

C) A titration curve cannot be generated for a strong acid-strong base reaction.

D) The moles of base needed to reach the equivalence point are greater for the strong acid than for the weak acid.

Correct Answer: B

The content specifies that the 'Equivalence point pH is neutral for strong acid-strong base titrations.' It also states that for weak acid titrations, the conjugate base hydrolyzes water, 'resulting in a basic...pH.'

A student performs a titration by adding 0.1 M NaOH to a solution of an unknown analyte. The pH at the equivalence point is measured to be 5.2. What is the nature of the unknown analyte?

A) A strong acid

B) A weak acid

C) A strong base

D) A weak base

Correct Answer: D

The titrant is a strong base. The equivalence point pH is acidic (pH < 7). According to the content, when the conjugate acid present at the equivalence point hydrolyzes water, it results in an acidic pH. This occurs when a weak base is titrated with a strong acid. The reverse (titrating a weak base with a strong base) is not standard, but the principle applies to the resulting pH. The question implies the analyte is an acid or base being titrated. An acidic equivalence point when titrating with a strong base means the analyte was the conjugate acid of a weak base, or more simply, a weak base was titrated by a strong acid. Let's re-read the question. It says NaOH is ADDED to an analyte. This means NaOH is the titrant. An acidic equivalence point means the analyte must be a weak base, whose conjugate acid makes the solution acidic at the equivalence point.

In the titration of a diprotic acid (H₂A) with a strong base, which species is the major component (besides water and spectator ions) in the solution at the first half-equivalence point?

A) Only H₂A

B) Equal concentrations of H₂A and HA⁻

C) Only HA⁻

D) Equal concentrations of HA⁻ and A²⁻

Correct Answer: B

The first half-equivalence point corresponds to the pKa of the first proton (H₂A ⇌ H⁺ + HA⁻). Applying the principle from monoprotic acids, the half-equivalence point is where the acid and its conjugate base are in equal concentrations. Therefore, [H₂A] = [HA⁻].

If 25.0 mL of a monoprotic acid solution requires 25.0 mL of 0.200 M NaOH to reach the equivalence point, what is the concentration of the acid?

A) 0.100 M

B) 0.200 M

C) 0.400 M

D) 0.500 M

Correct Answer: B

At the equivalence point, moles of acid = moles of base. Since the volumes are equal (25.0 mL), the concentrations must also be equal for the moles to be the same. This is an application of the principle that the equivalence point can be used to find the analyte's concentration.

What is the relationship between the concentration of a weak acid, [HA], and its conjugate base, [A⁻], at the half-equivalence point of a titration?

A) [HA] > [A⁻]

B) [HA] < [A⁻]

C) [HA] = [A⁻]

D) [HA] = 0

Correct Answer: C

The provided content explicitly states: 'For weak acid/base titrations, the half-equivalence point occurs when [HA] = [A⁻].'

A titration curve for a polyprotic acid shows its first equivalence point at 15.0 mL of added titrant and its second equivalence point at 30.0 mL. At which volume of added titrant can the value of pKa₂ be determined?

A) 7.5 mL

B) 15.0 mL

C) 22.5 mL

D) 30.0 mL

Correct Answer: C

The pKa for a given proton is found at the half-equivalence point for that proton's dissociation. The first pKa (pKa₁) is at 15.0/2 = 7.5 mL. The second dissociation occurs between the first and second equivalence points. The second half-equivalence point is halfway between 15.0 mL and 30.0 mL, which is (15.0 + 30.0) / 2 = 22.5 mL. At this volume, pH = pKa₂.