Q: A 0.10 M solution of acetic acid ($\mathrm{CH}_3\mathrm{COOH}$) has a $K_a = 1.8 \times 10^{-5}$. What is the equilibrium concentration of $\mathrm{H}_3\mathrm{O}^+$?

$[\mathrm{H}_3\mathrm{O}^+] = 1.34 \times 10^{-3}\ \mathrm{M}$

Q: If the $[\mathrm{H}_3\mathrm{O}^+]$ in a solution is $2.12 \times 10^{-3}\ \mathrm{M}$, what is the pH of the solution?

$\mathrm{pH} = -\log(2.12 \times 10^{-3}) = 2.67$

Q: A 0.25 M solution of ammonia ($\mathrm{NH}_3$) has a $K_b = 1.8 \times 10^{-5}$. What is the equilibrium concentration of $\mathrm{OH}^-$?

$[\mathrm{OH}^-] = 2.12 \times 10^{-3}\ \mathrm{M}$

Q: A solution has $[\mathrm{OH}^-] = 7.41 \times 10^{-12}\ \mathrm{M}$. What is the pOH of the solution?

$\mathrm{pOH} = -\log(7.41 \times 10^{-12}) = 11.13$

Question 1

Which of the following statements best describes the relationship between pH and pOH in aqueous solutions at 25°C?

Accepted Answer

$\mathrm{pH} + \mathrm{pOH} = 14.00$

Question 2

A 0.15 M solution of hydrochloric acid (HCl) is prepared. What is the pH of the solution?

Accepted Answer

$\mathrm{pH} = -\log(0.15) = 0.82$

Question 3

Which of the following acids is classified as a diprotic acid?

Accepted Answer

H$_2$SO$_4$

Question 4

What is the hydroxide ion concentration $[\mathrm{OH}^-]$ in a 0.15 M solution of barium hydroxide, Ba(OH)$_2$?

Accepted Answer

$[\mathrm{OH}^-] = 0.30\ \mathrm{M}$

Question 5

A 0.10 M solution of acetic acid ($\mathrm{CH}_3\mathrm{COOH}$) has a $K_a = 1.8 	imes 10^{-5}$. What is the equilibrium concentration of $\mathrm{H}_3\mathrm{O}^+$?

Accepted Answer

$[\mathrm{H}_3\mathrm{O}^+] = 1.34 	imes 10^{-3}\ \mathrm{M}$

Question 6

Which of the following best explains why the calculation of pH for a polyprotic acid like H$_3$PO$_4$ is more complex than for a monoprotic acid?

Accepted Answer

Polyprotic acids dissociate in multiple, sequential steps, each with its own equilibrium, requiring multiple ICE tables.

Question 7

If the $[\mathrm{H}_3\mathrm{O}^+]$ in a solution is $2.12 	imes 10^{-3}\ \mathrm{M}$, what is the pH of the solution?

Accepted Answer

$\mathrm{pH} = -\log(2.12 	imes 10^{-3}) = 2.67$

Question 8

A 0.25 M solution of ammonia ($\mathrm{NH}_3$) has a $K_b = 1.8 	imes 10^{-5}$. What is the equilibrium concentration of $\mathrm{OH}^-$?

Accepted Answer

$[\mathrm{OH}^-] = 2.12 	imes 10^{-3}\ \mathrm{M}$

Question 9

Which of the following is a correct expression for the acid dissociation constant ($K_a$) for the reaction $\mathrm{CH}_3\mathrm{COOH} + \mathrm{H}_2\mathrm{O} \rightleftharpoons \mathrm{H}_3\mathrm{O}^+ + \mathrm{CH}_3\mathrm{COO}^-$?

Accepted Answer

$K_a = \dfrac{[\mathrm{H}_3\mathrm{O}^+][\mathrm{CH}_3\mathrm{COO}^-]}{[\mathrm{CH}_3\mathrm{COOH}]}$

Question 10

Which of the following is a property of a strong acid in aqueous solution?

Accepted Answer

It completely ionizes in water.

Question 11

A solution has $[\mathrm{OH}^-] = 7.41 	imes 10^{-12}\ \mathrm{M}$. What is the pOH of the solution?

Accepted Answer

$\mathrm{pOH} = -\log(7.41 	imes 10^{-12}) = 11.13$

Question 12

Which of the following best describes a triprotic acid?

Accepted Answer

An acid that can donate three protons in solution, such as $\mathrm{H}_3\mathrm{PO}_4$

Question 13

A 0.10 M solution of phosphoric acid ($\mathrm{H}_3\mathrm{PO}_4$) has $K_{a1} = 7.5 	imes 10^{-3}$. What is the $[\mathrm{H}_3\mathrm{O}^+]$ at equilibrium for the first dissociation step?

Accepted Answer

$[\mathrm{H}_3\mathrm{O}^+] = 0.024\ \mathrm{M}$

Question 14

Which of the following is true about the dissociation of weak bases in water?

Accepted Answer

The $K_b$ value describes the degree of dissociation for a base.

Question 15

A solution has a pH of 1.62. What is the $[\mathrm{H}_3\mathrm{O}^+]$ concentration?

Accepted Answer

$[\mathrm{H}_3\mathrm{O}^+] = 10^{-1.62} = 0.024\ \mathrm{M}$

Question 16

Which of the following is a correct statement about the $K_a$ value of an acid?

Accepted Answer

A larger $K_a$ value means the acid is stronger.

Question 17

Which of the following best describes a monoprotic acid?

Accepted Answer

An acid that can donate only one proton per molecule, such as HCl

Question 18

A solution has a pOH of 0.52. What is the $[\mathrm{OH}^-]$ concentration?

Accepted Answer

$[\mathrm{OH}^-] = 10^{-0.52} = 0.30\ \mathrm{M}$

Acid-Base Equilibria and Measuring Acidity: General Chemistry Study Notes

Study Guide - Practice Questions

Study Guide - Flashcards