$K_a = \frac{[\text{products}]}{[\text{reactants}]}$

Question 1

Which of the following best describes an amphiprotic substance?

Accepted Answer

A substance that can act as both an acid and a base depending on the reaction conditions.

Question 2

What is the pH of a solution with $[H^+] = 1.0 	imes 10^{-4}$ M?

Accepted Answer

$pH = 4$

Question 3

Which equation correctly relates pH and $[H^+]$?

Accepted Answer

$pH = -\log [H^+]$

Question 4

A solution has a pH of 2. What is the concentration of hydrogen ions in the solution?

Accepted Answer

$[H^+] = 1.0 	imes 10^{-2}$ M

Question 5

Which of the following statements about the relationship between pH and acidity is correct?

Accepted Answer

As pH decreases, the solution becomes more acidic.

Question 6

If the $K_a$ of an acid is $1.0 	imes 10^{-5}$, what is its $pK_a$?

Accepted Answer

$pK_a = 5$

Question 7

Which of the following is the correct formula for the acid dissociation constant $K_a$?

Accepted Answer

$K_a = \frac{[	ext{products}]}{[	ext{reactants}]}$

Question 8

A buffer solution is prepared by mixing a weak acid and its conjugate base. Which statement best describes the function of the buffer?

Accepted Answer

It resists changes in pH when small amounts of acid or base are added.

Question 9

Which of the following is a correct representation of the autoionization of water?

Accepted Answer

$2H_2O \rightleftharpoons H_3O^+ + OH^-$

Question 10

A laboratory technician measures the pH of a solution and finds it to be 8. Which of the following best describes the solution?

Accepted Answer

The solution is basic.

Question 11

Which of the following is true about the relationship between $K_a$ and acid strength?

Accepted Answer

A larger $K_a$ value indicates a stronger acid.

Question 12

If the $[OH^-]$ in a solution is $1.0 	imes 10^{-6}$ M, what is the pOH?

Accepted Answer

$pOH = 6$

Question 13

Which of the following is the correct relationship between pH and pOH in aqueous solution at 25°C?

Accepted Answer

$pH + pOH = 14$

Question 14

A solution has $[H^+] = 2.5 	imes 10^{-3}$ M. What is the pH of the solution?

Accepted Answer

$pH = 2.60$

Question 15

Which of the following laboratory methods is most appropriate for accurately measuring the pH of a solution?

Accepted Answer

Using a pH meter.

Question 16

Which of the following is the conjugate base of $HCO_3^-$?

Accepted Answer

$CO_3^{2-}$

Question 17

Which of the following is a correct statement about the significance of pH units?

Accepted Answer

A change in pH by 1 unit represents a tenfold change in $[H^+]$ concentration.

Question 18

Which of the following is the correct formula for calculating $K_w$ for water?

Accepted Answer

$K_w = [H^+][OH^-]$

Question 19

Which of the following best describes a strong base?

Accepted Answer

A substance that completely dissociates in water to produce $OH^-$ ions.

Acids and Bases: pH, pKa, and Related Concepts

Study Guide - Practice Questions