$[H^+][OH^-] = 1 \times 10^{-14}$

Acidic; $[H^+] = 1 \times 10^{-3}\ \mathrm{M}$

Question 1

Which of the following best describes the auto-ionization of water as shown in the first image?

Accepted Answer

Water molecules react with each other to form $\mathrm{OH^-}$ and $\mathrm{H_3O^+}$ ions.

Question 2

Given the equation $\mathrm{pH = -log[H^+]}$, what is the pH of a solution with $[H^+] = 1 	imes 10^{-4}\ \mathrm{M}$?

Accepted Answer

$4$

Question 3

Which of the following substances from the pH scale image is most likely to have a pH closest to 2?

Accepted Answer

Lemon juice

Question 4

If a solution has a pH of 12, which of the following statements is true?

Accepted Answer

The solution is basic and has a low concentration of $[H^+]$ ions.

Question 5

Which equation correctly represents the relationship between $[H^+]$ and $[OH^-]$ in pure water at 25°C?

Accepted Answer

$[H^+][OH^-] = 1 	imes 10^{-14}$

Question 6

A student adds a small amount of hydrochloric acid ($\mathrm{HCl}$) to pure water. What happens to the pH and $[H^+]$ of the solution?

Accepted Answer

The pH decreases and $[H^+]$ increases.

Question 7

Which of the following best defines a base according to the Brønsted-Lowry theory?

Accepted Answer

A substance that accepts a proton ($H^+$).

Question 8

If the $[OH^-]$ in a solution is $1 	imes 10^{-3}\ \mathrm{M}$, what is the pOH of the solution?

Accepted Answer

$3$

Question 9

A solution has a pH of 5. What is the $[H^+]$ concentration?

Accepted Answer

$1 	imes 10^{-5}\ \mathrm{M}$

Question 10

Which of the following real-life scenarios best illustrates the concept of a buffer solution?

Accepted Answer

Human blood maintaining a nearly constant pH despite the addition of acids or bases.

Question 11

Which of the following is the correct formula for calculating pOH?

Accepted Answer

$\mathrm{pOH = -log[OH^-]}$

Question 12

If a solution has a pH of 3, what is its classification and approximate $[H^+]$?

Accepted Answer

Acidic; $[H^+] = 1 	imes 10^{-3}\ \mathrm{M}$

Question 13

Which of the following best explains why the pH scale is logarithmic?

Accepted Answer

It allows us to express a wide range of $[H^+]$ concentrations in a compact form.

Question 14

A solution has $[H^+] = 1 	imes 10^{-9}\ \mathrm{M}$. What is its pH and is it acidic, basic, or neutral?

Accepted Answer

pH = 9; basic

Question 15

Which of the following best describes the role of water in the auto-ionization reaction shown in the first image?

Accepted Answer

Water acts as both an acid and a base.

Question 16

If the pH of a solution is 8, what is the pOH at 25°C?

Accepted Answer

$6$

Question 17

Which of the following household substances is most likely to have a pH greater than 10, based on the pH scale image?

Accepted Answer

Bleach

Question 18

A solution has a pOH of 2. What is the $[OH^-]$ concentration?

Accepted Answer

$1 	imes 10^{-2}\ \mathrm{M}$

Question 19

Which of the following best describes why pure water is considered neutral?

Accepted Answer

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

Acids, Bases, and the pH Scale: Quantitative Expression of Acidity and Basicity

Study Guide - Practice Questions