Acid-Base Labs (PS 21)

1.

At what point is the solution at its most basic?

A

B

C

D

E

The solution is at its most basic at point E.

Explanation

The solution is at its most basic at point E.

2.

At what point has the titration reached its equivalence point?

A

B

C

D

E

The titration has reached its equivalence point when the moles of the titrant added are stoichiometrically equivalent to the moles of the analyte present in the solution. This means that the reaction is complete and there is no excess of either the titrant or the analyte. Option D is the correct answer because it represents the point where the equivalence point is reached, indicating that the titration is complete.

Explanation

The titration has reached its equivalence point when the moles of the titrant added are stoichiometrically equivalent to the moles of the analyte present in the solution. This means that the reaction is complete and there is no excess of either the titrant or the analyte. Option D is the correct answer because it represents the point where the equivalence point is reached, indicating that the titration is complete.

3. Which of the following is a correct method for preparing a buffer solution? I. Mix the correct amount of a weak acid and its conjugate base II. Neutralize a weak base partially with strong acid III. Neutralize a weak acid partially with a strong base

I only

II only

III only

II and III only

I, II and III

not-available-via-ai

Explanation

not-available-via-ai

4.

At what point in the titration is the pH of the solution equal to the pKa of the acid?

A

B

C

D

E

The pH of a solution is equal to the pKa of the acid at the halfway point of the titration, which is represented by answer choice B. At this point, half of the acid has been neutralized by the base, resulting in equal concentrations of the acid and its conjugate base. This creates a buffer solution and the pH is equal to the pKa of the acid.

Explanation

The pH of a solution is equal to the pKa of the acid at the halfway point of the titration, which is represented by answer choice B. At this point, half of the acid has been neutralized by the base, resulting in equal concentrations of the acid and its conjugate base. This creates a buffer solution and the pH is equal to the pKa of the acid.

5. A solution containing HF is titrated with KOH. At the end point of the titration the solution contains

Equal amounts of HF and KOH

At the end point of the titration, the solution contains equal amounts of HF and KOH because the titration is a neutralization reaction between an acid (HF) and a base (KOH). The reaction between HF and KOH produces water (H2O) and a salt, potassium fluoride (KF). Since the reaction is stoichiometrically balanced, equal amounts of HF and KOH are required to reach the end point where all the acid has reacted with the base. Therefore, at the end point, the solution contains equal amounts of HF and KOH.

Explanation

At the end point of the titration, the solution contains equal amounts of HF and KOH because the titration is a neutralization reaction between an acid (HF) and a base (KOH). The reaction between HF and KOH produces water (H2O) and a salt, potassium fluoride (KF). Since the reaction is stoichiometrically balanced, equal amounts of HF and KOH are required to reach the end point where all the acid has reacted with the base. Therefore, at the end point, the solution contains equal amounts of HF and KOH.

ACID-base Labs (Ps 21)