Question 1

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

Accepted Answer

Sodium acetate, NaC2H3O2

Question 2

A 0.10 mol/L solution of ammonium chloride, NH4Cl(aq), has a pH less than 7. Which statement best explains this observation?

Accepted Answer

The NH4^+ ion is the conjugate acid of a weak base and donates protons to water, increasing [H^+].

Question 3

Which of the following equations correctly represents the hydrolysis of the ethanoate ion, C2H3O2^-, in water?

Accepted Answer

$$\mathrm{C_2H_3O_2^- (aq) + H_2O (l) \rightleftharpoons HC_2H_3O_2 (aq) + OH^- (aq)}$$

Question 4

Which of the following best describes the pH of a solution of potassium nitrate, KNO3(aq)?

Accepted Answer

Neutral, because both K^+ and NO3^- are ions from strong acid and strong base and do not hydrolyze.

Question 5

A 0.30 mol/L solution of sodium nitrite, NaNO2(aq), has a pH of 8.41. Which calculation step is necessary to determine this pH?

Accepted Answer

Calculate $$K_b$$ for NO2^- using $$K_w$$ and $$K_a$$ for HNO2, then solve for [OH^-] at equilibrium.

Question 6

Which of the following best predicts the pH of a solution of sodium hydrogen carbonate, NaHCO3(aq)?

Accepted Answer

Basic, because the HCO3^- ion acts as a base and its $$K_b is $$greater than its $$K_a.$$

Question 7

Which of the following statements is true regarding the hydrolysis of metallic and non-metallic oxides?

Accepted Answer

Metallic oxides form basic solutions, while non-metallic oxides form acidic solutions.

Question 8

A solution is made by dissolving aluminum chloride, AlCl3, in water. Which of the following best explains why the solution is acidic?

Accepted Answer

The hydrated $$Al^3+ $$ion acts as a weak acid, releasing H^+ ions into solution.

Question 9

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

Accepted Answer

Potassium chloride, KCl

Question 10

A solution is prepared by dissolving sodium hypochlorite, NaClO, in water. The $$K_a$$ for HClO is $$3.5 	imes 10$$^{-8}$$. What is the correct expression for the K_b$ of ClO^-?

Accepted Answer

$$K_b = \frac{K_w}{K_a}$$

Question 11

Which of the following best describes the solution formed when ammonium ethanoate, NH4C2H3O2, is dissolved in water?

Accepted Answer

The solution may be acidic, basic, or neutral depending on the relative values of $$K_a$$ for NH4^+ and $$K_b$$ for C2H3O2^-.

Question 12

Which of the following is the correct net ionic equation for the reaction of carbon dioxide with water to form an acidic solution?

Accepted Answer

$$\mathrm{CO_2$ (g) + 2 H_2O (l) \rightarrow H_3O^+ (aq) + $$HCO_3$$^- (aq)}$$

Question 13

A 0.10 mol/L solution of codeine hydrochloride, DHCl(aq), has a pH of 4.91. Codeine is a weak base with $$K_b = 1.62 	imes 10$$^{-6}$$. Which of the following best explains why the solution is acidic?

Accepted Answer

The D^+ ion (conjugate acid of codeine) hydrolyzes to produce H^+ ions.

Question 14

Which of the following best describes the effect of adding calcium oxide, CaO, to water?

Accepted Answer

It forms a basic solution by producing $$Ca^{2+}$$ and OH^- ions.

Question 15

A solution is made by bubbling nitrogen dioxide, NO2(g), into water. What is the expected pH of the solution and why?

Accepted Answer

Acidic, because NO2 is a non-metallic oxide and forms acids in water.

Question 16

Which of the following best explains why a solution of sodium fluoride, NaF(aq), is basic?

Accepted Answer

The F^- ion is the conjugate base of a weak acid and hydrolyzes to produce OH^- ions.

Question 17

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

Accepted Answer

$$K_a 	imes K_b = K_w$$

Question 18

A solution is prepared by dissolving magnesium sulfate, MgSO4, in water. Predict the pH of the solution and explain your reasoning.

Accepted Answer

Neutral, because both $$Mg^{2+}$$ and $$SO4^{2-}$$ are ions of strong acid and strong base and do not hydrolyze significantly.

Question 19

Which of the following best describes the effect of the hydrated $$Al^{3+}$$ ion in aqueous solution?

Accepted Answer

It acts as a weak acid, releasing H^+ ions and lowering the pH.

Lesson 8.6: Acid–Base Properties of Salt Solutions

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