$1 \times 10^{-3}\ \mathrm{mol\ L^{-1}}$

Question 1

Which of the following best describes the Brønsted-Lowry definition of an acid?

Accepted Answer

A substance that donates a proton (H+) to another substance.

Question 2

Which reaction demonstrates the amphiprotic nature of water?

Accepted Answer

$\mathrm{H_2O + H_2O \rightleftharpoons H_3O^+ + OH^-}$

Question 3

A solution has a pH of 3. What is the concentration of $\mathrm{H^+}$ ions in the solution?

Accepted Answer

$1 	imes 10^{-3}\ \mathrm{mol\ L^{-1}}$

Question 4

Which of the following pairs is a conjugate acid-base pair?

Accepted Answer

$\mathrm{NH_4^+}$ / $\mathrm{NH_3}$

Question 5

Which of the following statements about the pH and pOH of an aqueous solution at 22°C is correct?

Accepted Answer

$\mathrm{pH + pOH = 14}$

Question 6

Which of the following acids is the strongest according to the data provided?

Accepted Answer

Hydrochloric acid ($\mathrm{HCl}$)

Question 7

If $\mathrm{K_a}$ for acetic acid is $1.7 	imes 10^{-5}$, what is its $\mathrm{pK_a}$?

Accepted Answer

$4.77$

Question 8

Which of the following best explains why HF is a weaker acid than HCl, even though fluorine is more electronegative?

Accepted Answer

The H–F bond is much stronger than the H–Cl bond, making it harder to lose a proton.

Question 9

A titration curve of a weak acid with a strong base will show:

Accepted Answer

A buffer region before the equivalence point.

Question 10

Which of the following is true for the relationship between $\mathrm{K_a}$ and $\mathrm{K_b}$ for a conjugate acid-base pair?

Accepted Answer

$\mathrm{K_a \cdot K_b = K_w}$

Question 11

Which of the following substances is amphiprotic?

Accepted Answer

Water ($\mathrm{H_2O}$)

Question 12

A solution is prepared by dissolving ammonia ($\mathrm{NH_3}$) in water. According to the Brønsted-Lowry concept, what role does ammonia play?

Accepted Answer

Base, because it accepts a proton from water.

Question 13

Which of the following equations correctly represents the autoprotolysis of water?

Accepted Answer

$\mathrm{2H_2O \rightleftharpoons H_3O^+ + OH^-}$

Question 14

If the $\mathrm{pK_a}$ of $\mathrm{H_2PO_4^-}$ is 7.21, what is the $\mathrm{pK_b}$ of its conjugate base $\mathrm{HPO_4^{2-}}$?

Accepted Answer

$6.79$

Question 15

During a titration of a strong acid with a strong base, what is observed at the equivalence point?

Accepted Answer

The number of moles of acid equals the number of moles of base.

Question 16

Which of the following is a correct statement about the relationship between $\mathrm{pK_a}$ and acid strength?

Accepted Answer

The lower the $\mathrm{pK_a}$, the stronger the acid.

Question 17

Which of the following best describes why the activity of water is set to 1 in equilibrium calculations?

Accepted Answer

Because water is both the solvent and a reactant, its activity is defined as 1.

Question 18

A buffer solution is prepared using acetic acid and sodium acetate. Which equation describes the equilibrium in this buffer?

Accepted Answer

$\mathrm{CH_3COOH \rightleftharpoons CH_3COO^- + H^+}$

Question 19

Which of the following is NOT a strong base?

Accepted Answer

NH$_3$

Acids and Bases: Concepts, Strength, and Titration

Study Guide - Practice Questions