Question 1

Which of the following statements best explains why the pH at the equivalence point of a weak acid/strong base titration is greater than 7?

Accepted Answer

The conjugate base of the weak acid hydrolyzes to produce OH$$^-$$ ions, increasing the pH.

Question 2

During the titration of a monoprotic weak acid with a strong base, what is the relationship between pH and pKa at the half-equivalence point?

Accepted Answer

pH = pKa

Question 3

A student titrates 25.0 mL of a 0.10 M monoprotic acid with 0.10 M NaOH. What volume of NaOH is required to reach the equivalence point?

Accepted Answer

$$25.0\ \mathrm{mL}$$

Question 4

Which of the following best describes the function of a pH electrode during a titration?

Accepted Answer

It measures the potential difference across a hydrogen-ion-sensitive glass membrane.

Question 5

In a titration curve for a diprotic acid, how many equivalence points are observed and what do they represent?

Accepted Answer

Two equivalence points, each corresponding to the neutralization of one acidic proton.

Question 6

Which equation is used to determine the pH at any point during the titration of a weak acid with a strong base?

Accepted Answer

$$\mathrm{pH} = \mathrm{p}K_a + \log \left( \frac{[A^-]}{[HA]} \right)$$

Question 7

A titration curve shows a very steep rise in pH near the equivalence point. What does this indicate about the acid being titrated?

Accepted Answer

The acid is strong.

Question 8

Why is it important to calibrate a pH meter before use in a titration experiment?

Accepted Answer

To ensure accurate pH readings by correcting for electrode drift and environmental factors.

Question 9

Which of the following is a major advantage of using a pH meter over a colorimetric indicator in acid-base titrations?

Accepted Answer

A pH meter provides quantitative and continuous pH measurements, allowing for more precise determination of the equivalence point.

Question 10

During the titration of a weak acid with a strong base, what is the main chemical species present at the equivalence point?

Accepted Answer

The conjugate base of the weak acid.

Question 11

A student is titrating an unknown acid and observes two distinct equivalence points on the titration curve. What can be concluded about the acid?

Accepted Answer

The acid is diprotic.

Question 12

If the pH at the half-equivalence point of a titration is measured to be 4.7, what is the pKa of the acid?

Accepted Answer

$$4.7$$

Question 13

Which of the following errors is most likely to occur when using a colorimetric indicator instead of a pH meter in a titration?

Accepted Answer

The endpoint may not coincide exactly with the equivalence point, leading to systematic error.

Question 14

A titration curve for carbonic acid (H$$_2CO$_3) $$titrated with NaOH shows two buffer regions. What do these regions correspond to?

Accepted Answer

The regions where the solution resists changes in pH due to the presence of both acid and its conjugate base.

Question 15

Which plot is most useful for precisely locating the equivalence point in a titration curve?

Accepted Answer

The first derivative plot, $$\frac{\Delta \mathrm{pH}}{\Delta V}$$, which shows a maximum at the equivalence point.

Question 16

What is the equivalent weight of an acid with a molar mass of 180 g/mol and two acidic protons?

Accepted Answer

$$90\ \mathrm{g/equiv}$$

Question 17

Which of the following best explains why the vertical height of the titration curve near the equivalence point is smaller for a weak acid than for a strong acid?

Accepted Answer

A weak acid only partially ionizes, so the change in pH is less dramatic near the equivalence point.

pH Meter Calibration and Acid-Base Titrations: Analytical Chemistry Laboratory Study Notes

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