Q: Calculate the $$[H_3O^+] in a $$solution with $$pH = 4.3.$$

$$[H_3O^+] = 5.0 \times 10$$^{-5}$$\,M$$

Q: A 0.10 M solution of HCl is prepared at 25°C. What is the $$[OH^-] in $$this solution?

$$[OH^-] = 1.0 \times 10$$^{-13}$$\,M$$

Q: Which of the following acids is the strongest based on their $$K_a$$ values?

Hydrofluoric acid, $$K_a = 6.8 \times 10$$^{-4}$$

Q: A solution has $$pH = 9.0 at 25$$°C. What is the $$[OH^-]$$?

$$[OH^-] = 1.0 \times 10$$^{-5}$$\,M$$

Question 1

Which of the following statements best describes the autoionization of water at 25°C?

Accepted Answer

Two water molecules react to form one hydronium ion and one hydroxide ion: $$2\,H_2O \rightleftharpoons H_3O^+ + OH^-$$

Question 2

A solution has $$[OH^-] = 6.7 	imes 10$$^{-3}$$\,M at 25$$°C. What is the pH of the solution?

Accepted Answer

$$pH = 2.17$$

Question 3

Which of the following is true for a strong monoprotic acid in aqueous solution?

Accepted Answer

The acid completely ionizes, so $$[H^+] = [acid]_{initial}.$$

Question 4

Calculate the $$[H_3O^+] in a $$solution with $$pH = 4.3.$$

Accepted Answer

$$[H_3O^+] = 5.0 	imes 10$$^{-5}$$\,M$$

Question 5

Which equation correctly relates $$pH$$ and $$pOH at 25$$°C?

Accepted Answer

$$pH + pOH = 14$$

Question 6

A 0.10 M solution of HCl is prepared at 25°C. What is the $$[OH^-] in $$this solution?

Accepted Answer

$$[OH^-] = 1.0 	imes 10$$^{-13}$$\,M$$

Question 7

Which of the following acids is the strongest based on their $$K_a$$ values?

Accepted Answer

Hydrofluoric acid, $$K_a = 6.8 	imes 10$$^{-4}$$

Question 8

A weak acid, HA, has an initial concentration of 0.20 M and at equilibrium, $$[A^-] = 0.01\,M. $$What is the percent ionization?

Accepted Answer

5%

Question 9

Which of the following best explains why $$K_{a1} \u003e K_{a2}$$ for a polyprotic acid?

Accepted Answer

The first proton is easier to remove due to less electrostatic repulsion.

Question 10

Which of the following is the correct expression for the acid dissociation constant, $$K_a$$, for the reaction $$HA(aq) \rightleftharpoons H^+(aq) + A^-(aq)$$?

Accepted Answer

$$K_a = \frac{[H^+][A^-]}{[HA]}$$

Question 11

A solution has $$pH = 9.0 at 25$$°C. What is the $$[OH^-]$$?

Accepted Answer

$$[OH^-] = 1.0 	imes 10$$^{-5}$$\,M$$

Question 12

Which of the following is a correct relationship for a weak base, $$B$$, in water?

Accepted Answer

$$pOH = pK_b + \log \frac{[HB^+]}{[B]}$$

Question 13

Which of the following best describes the effect of increasing electronegativity of the central atom in an oxyacid (Y-OH) on acidity?

Accepted Answer

Acidity increases as the electronegativity of Y increases.

Question 14

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

Accepted Answer

$$K_a 	imes K_b = K_w$$

Question 15

A sore throat medication contains phenol ($$HC_6H_5O). A 0.10 M $$solution has $$pH = 5.43. $$What is the $$K_a$$ for phenol?

Accepted Answer

$$K_a = 1.3 	imes 10$$^{-10}$$

Question 16

Which of the following methods is most precise for measuring the pH of a solution?

Accepted Answer

Using a pH meter.

Question 17

Which of the following best describes a strong base?

Accepted Answer

A base that completely dissociates in water, so $$[OH^-] = [base]_{initial}.$$

Question 18

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

Accepted Answer

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

Question 19

Which of the following solutions is most basic at 25°C?

Accepted Answer

A solution with $$[OH^-] = 1.0 	imes 10$$^{-1}$$\,M$$

Acid-Base Equilibria: Study Notes for GOB Chemistry

Study Guide - Practice Questions

Study Guide - Flashcards