Q: A solution has $$[\mathrm{H_3O^+}] = 2.5 \times 10$$^{-3}$$\ \mathrm{M}. $$What is the $$[\mathrm{OH^-}] at 25$$°C?

$$4.0 \times 10$$^{-12}$$\ \mathrm{M}$$

Q: A lake has a pH of 4.5 due to acid rain. What is the $$[\mathrm{H_3O^+}] in $$the lake?

$$3 \times 10$$^{-5}$$\ \mathrm{M}$$

Question 1

Which of the following statements best describes a Brønsted–Lowry acid?

Accepted Answer

A substance that donates a proton (H+).

Question 2

Given the reaction $$\mathrm{NH_3$(aq) + H_2O(l) \rightleftharpoons NH_4$^+(aq) + OH^-(aq)}$$, identify the conjugate acid–base pairs.

Accepted Answer

$$\mathrm{NH_3$}$$/$$\mathrm{NH_4$^+}$$ and $$\mathrm{H_2O}$$/$$\mathrm{OH^-}$$

Question 3

Which of the following is a limitation of the Arrhenius theory of acids and bases?

Accepted Answer

It is restricted to aqueous solutions and does not explain the basicity of substances like $$\mathrm{NH_3$}.$$

Question 4

Which of the following best describes a Lewis acid?

Accepted Answer

An electron-pair acceptor.

Question 5

Which of the following acids is the strongest, based on the bond strength trend for binary acids in the same group?

Accepted Answer

$$\mathrm{HI}$$

Question 6

A solution has $$[\mathrm{H_3O^+}] = 2.5 	imes 10$$^{-3}$$\ \mathrm{M}. $$What is the $$[\mathrm{OH^-}] at 25$$°C?

Accepted Answer

$$4.0 	imes 10$$^{-12}$$\ \mathrm{M}$$

Question 7

Which of the following salts will produce a basic solution when dissolved in water?

Accepted Answer

$$\mathrm{NaCN}$$

Question 8

Calculate the pH of a $$0.025\ \mathrm{M}$$ solution of $$\mathrm{$$HNO_3$$} (a $$strong acid).

Accepted Answer

$$1.60$$

Question 9

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

Accepted Answer

$$K_a 	imes K_b = K_w$$

Question 10

A $$0.10\ \mathrm{M}$$ solution of $$\mathrm{HCN}$$ has $$K_a = 4.9 	imes 10$$^{-10}$$. What is the pH of the solution?

Accepted Answer

$$5.15$$

Question 11

Which of the following indicators would be most suitable for detecting the endpoint of a titration between a strong acid and a strong base?

Accepted Answer

Bromothymol blue (pH range 6.0–7.6)

Question 12

Which of the following factors increases the acid strength of oxoacids $$\mathrm{H_nYO_m}$$ when the central atom Y is the same?

Accepted Answer

Increasing the number of oxygen atoms.

Question 13

Which of the following is the correct expression for the acid dissociation constant $$K_a$$ for the reaction $$\mathrm{HA(aq) + H_2O(l) \rightleftharpoons H_3O^+(aq) + A^-(aq)}$$?

Accepted Answer

$$K_a = \frac{[\mathrm{H_3O^+}][\mathrm{A^-}]}{[\mathrm{HA}]}$$

Question 14

A lake has a pH of 4.5 due to acid rain. What is the $$[\mathrm{H_3O^+}] in $$the lake?

Accepted Answer

$$3 	imes 10$$^{-5}$$\ \mathrm{M}$$

Question 15

Which of the following best explains why $$K_{a1} \u003e K_{a2} \u003e K_{a3}$$ for a polyprotic acid?

Accepted Answer

It is harder to remove a proton from a negatively charged species than from a neutral species.

Question 16

Which of the following is a Brønsted–Lowry base?

Accepted Answer

$$\mathrm{H_2O}$$

Question 17

Which of the following best describes the pH of a solution of $$\mathrm{CH_3NH_3I} in $$water?

Accepted Answer

Acidic

Question 18

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

Accepted Answer

$$\mathrm{pH} + \mathrm{pOH} = 14$$

Question 19

Which of the following is a Lewis base in the reaction $$\mathrm{Cu$$^{2+}$$ + 4NH_3 \rightarrow [Cu(NH_3$)_4]^{2+}}$$?

Accepted Answer

$$\mathrm{NH_3$}$$

Aqueous Equilibria: Acids and Bases – Study Notes

Study Guide - Practice Questions

Study Guide - Flashcards