Chapter 14

Define a Brønsted-Lowry acid and a Brønsted-Lowry base.

Explain in your own words what \(100 \%\) ionization means.

Write the chemical equation for the autoionization of water. Write the equilibrium constant expression for this reaction. What is the value of the equilibrium constant at \(25^{\circ} \mathrm{C} ?\) What is this constant called?

When \(\mathrm{OH}^{-}\) is the base in a conjugate acid-base pair, the acid is ________ ; when \(\mathrm{OH}^{-}\) is the acid, the base is __________.

Designate the acid and the base on the left side of these equations, and designate the conjugate partner of each on the right side. (a) \(\mathrm{HNO}_{3}(\mathrm{aq})+\mathrm{H}_{2} \mathrm{O}(\ell) \longrightarrow \mathrm{H}_{3} \mathrm{O}^{+}(\mathrm{aq})+\mathrm{NO}_{3}^{-}(\mathrm{aq})\) (b) \(\mathrm{NH}_{4}^{+}(\mathrm{aq})+\mathrm{CN}^{-}(\mathrm{aq}) \longrightarrow \mathrm{NH}_{3}(\mathrm{aq})+\mathrm{HCN}(\mathrm{aq})\)

Dissolving ammonium bromide in water gives an acidic solution. Write a balanced equation showing how that can occur.

Solution A has a pH of 8 and solution \(\mathrm{B}\) a p \(\mathrm{H}\) of 10 Which has the greater hydronium ion concentration? How many times greater is its concentration?

Contrast the main ideas of the Brønsted-Lowry and Lewis acid-base definitions. Name and write the formula for a substance that behaves as a Lewis acid but not as a Brønsted-Lowry acid.

Write a chemical equation to describe the proton transfer that occurs when each of these acids is added to water. (a) \(\mathrm{HCO}_{3}^{-}\) (b) HCl (c) \(\mathrm{CH}_{3} \mathrm{COOH}\) (d) HCN

Write a chemical equation to describe the proton transfer that occurs when each of these acids is added to water. (a) HIO (b) \(\mathrm{CH}_{3}\left(\mathrm{CH}_{2}\right)_{4} \mathrm{COOH}\) (c) HOOCCOOH (d) \(\mathrm{CH}_{3} \mathrm{NH}_{3}^{+}\)

Write a chemical equation to describe the proton transfer that occurs when each of these bases is added to water. (a) \(\mathrm{HSO}_{4}^{-}\) (b) \(\mathrm{CH}_{3} \mathrm{NH}_{2}\) (c) I (d) \(\mathrm{H}_{2} \mathrm{PO}_{4}^{-}\)

Write a chemical equation to describe the proton transfer that occurs when each of these bases is added to water. (a) \(\mathrm{PO}_{4}^{3-}\) (b) \(\mathrm{SO}_{3}^{2-}\) (c) \(\mathrm{HPO}_{4}^{2-}\)

Write the formula and name for the conjugate partner for each acid or base. (a) HI (b) \(\mathrm{NO}_{3}^{-}\) (c) \(\mathrm{CO}_{3}^{2-}\) (d) \(\mathrm{H}_{2} \mathrm{CO}_{3}\) (e) \(\mathrm{HSO}_{4}^{-}\) (f) \(\mathrm{SO}_{3}^{2-}\)

Write the formula and name for the conjugate partner for each acid or base. (a) \(\mathrm{CN}^{-}\) (b) \(\mathrm{SO}_{4}^{2-}\) (c) \(\mathrm{HS}^{-}\) (d) \(S^{2-}\) (e) \(\mathrm{HSO}_{3}^{-}\) (f) HCOOH (formic acid)

Which are conjugate acid-base pairs? (a) \(\mathrm{NH}_{2}^{-}\) and \(\mathrm{NH}_{4}^{+}\) (b) \(\mathrm{NH}_{3}\) and \(\mathrm{NH}_{2}^{-}\) (c) \(\mathrm{H}_{3} \mathrm{O}^{+}\) and \(\mathrm{H}_{2} \mathrm{O}\) (d) \(\mathrm{OH}^{-}\) and \(\mathrm{O}^{2-}\) (e) \(\mathrm{H}_{3} \mathrm{O}^{+}\) and \(\mathrm{OH}^{-}\)

Which are conjugate acid-base pairs? (a) \(\mathrm{O}^{2-}\) and \(\mathrm{H}_{3} \mathrm{O}^{+}\) (b) \(\mathrm{H}_{3} \mathrm{O}^{+}\) and \(\mathrm{O}^{2-}\) (c) \(\mathrm{NH}_{2}^{-}\) and \(\mathrm{NH}_{3}\) (d) \(\mathrm{NH}_{3}\) and \(\mathrm{NH}_{4}^{+}\) (e) \(\mathrm{O}^{2-}\) and \(\mathrm{H}_{2} \mathrm{O}\)

Identify the acid and the base that are reactants in each equation; identify the conjugate base and conjugate acid on the product side of the equation. (a) \(\mathrm{HS}^{-}(\mathrm{aq})+\mathrm{H}_{2} \mathrm{O}(\ell) \longrightarrow \mathrm{H}_{2} \mathrm{~S}(\mathrm{aq})+\mathrm{OH}^{-}(\mathrm{aq})\) (b) \(\mathrm{S}^{2-}(\mathrm{aq})+\mathrm{NH}_{4}^{+}(\mathrm{aq}) \longrightarrow \mathrm{NH}_{3}(\mathrm{~g})+\mathrm{HS}^{-}(\mathrm{aq})\) (c) \(\mathrm{HCO}_{3}^{-}(\mathrm{aq})+\mathrm{HSO}_{4}^{-}(\mathrm{aq}) \longrightarrow \mathrm{H}_{2} \mathrm{CO}_{3}(\mathrm{aq})+\mathrm{SO}_{4}^{2-}(\mathrm{aq})\) (d) \(\mathrm{NH}_{3}(\mathrm{aq})+\mathrm{NH}_{2}^{-}(\mathrm{aq}) \longrightarrow \mathrm{NH}_{2}^{-}(\mathrm{aq})+\mathrm{NH}_{3}(\mathrm{aq})\)

Identify the acid and the base that are reactants in each equation; identify the conjugate base and conjugate acid on the product side of the equation. (a) \(\mathrm{CN}^{-}(\mathrm{aq})+\mathrm{CH}_{3} \mathrm{COOH}(\mathrm{aq}) \longrightarrow\) \(\mathrm{CH}_{3} \mathrm{COO}^{-}(\mathrm{aq})+\mathrm{HCN}(\mathrm{aq})\) (b) \(\mathrm{O}^{2-}(\mathrm{aq})+\mathrm{H}_{2} \mathrm{O}(\ell) \longrightarrow 2 \mathrm{OH}^{-}(\mathrm{aq})\) (c) \(\mathrm{HCO}_{2}^{-}(\mathrm{aq})+\mathrm{H}_{2} \mathrm{O}(\ell) \longrightarrow \mathrm{HCOOH}(\mathrm{aq})+\mathrm{OH}^{-}(\mathrm{aq})\)

Consider these four solutions: $$ \begin{array}{lcc} \hline \text { Solution } & {\left[\mathrm{H}_{3} \mathrm{O}^{+}\right](\mathrm{M})} & {\left[\mathrm{OH}^{-}\right](\mathrm{M})} \\ \hline \mathrm{D} & 2 \times 10^{-3} & \\ \mathrm{E} & & 2 \times 10^{-7} \\ \mathrm{~F} & 4 \times 10^{-5} & \\ \mathrm{G} & & 5 \times 10^{-11} \\ \hline \end{array} $$ (a) Which solution has the highest \(\mathrm{H}_{3} \mathrm{O}^{+}\) concentration? (b) Which solution has the highest \(\mathrm{OH}^{-}\) concentration? (c) Which solution is closest to being a neutral solution?

Consider these four solutions: $$ \begin{array}{lcc} \hline \text { Solution } & {\left[\mathrm{H}_{3} \mathrm{O}^{+}\right](\mathrm{M})} & {\left[\mathrm{OH}^{-}\right](\mathrm{M})} \\ \hline \mathrm{W} & 5 \times 10^{-6} & \\ \mathrm{X} & & 2 \times 10^{-4} \\ \mathrm{Y} & 4 \times 10^{-2} & \\ \mathrm{Z} & & 5 \times 10^{-11} \\ \hline \end{array} $$ (a) Which solution has the highest \(\mathrm{H}_{3} \mathrm{O}^{+}\) concentration? (b) One solution's \(\mathrm{H}_{3} \mathrm{O}^{+}\) concentration is equal to the \(\mathrm{OH}^{-}\) concentration of a different solution. Identify the two solutions and their concentrations. (c) Which solution is closest to being a neutral solution?

Pyridine, \(\mathrm{C}_{5} \mathrm{H}_{5} \mathrm{~N},\) is a weak base. Write a balanced chemical equation to represent why an aqueous solution of pyridine is basic.

Amantadine, \(\mathrm{C}_{10} \mathrm{H}_{15} \mathrm{NH}_{2}\), is a base used to treat Parkinson's disease. Write a balanced chemical equation to represent why an aqueous solution of amantadine is basic.

Pyruvic acid, \(\mathrm{CH}_{3} \mathrm{COCOOH},\) is produced during aerobic respiration. Write a balanced chemical equation to represent why an aqueous solution of pyruvic acid is acidic.

Formic acid, \(\mathrm{HCOOH}\), is found in ants. Write a balanced chemical equation to represent why an aqueous solution of formic acid is acidic.

Milk of magnesia, \(\mathrm{Mg}(\mathrm{OH})_{2}\), has a pH of 10.5. Calculate the hydronium ion concentration of the solution. Is this solution acidic or basic?

A sample of coffee has a pH of 4.3. Calculate the hydronium ion concentration in this coffee. Is the coffee acidic or basic?

Calculate the \(\mathrm{pH}\) of a solution that is \(0.025-\mathrm{M}\) in \(\mathrm{NaOH}\). Calculate the pOH of this solution.

Calculate the pH of a 0.0013-M solution of \(\mathrm{HNO}_{3} .\) Calculate the pOH of this solution.

The hydronium ion concentration of a cyanoacetic acid solution is \(0.032 \mathrm{M}\). Calculate its pOH.

A solution of benzyl amine, \(\mathrm{C}_{7} \mathrm{H}_{7} \mathrm{NH}_{2}\), has a hydroxide ion concentration of \(2.4 \times 10^{-3} \mathrm{M}\). Calculate the \(\mathrm{pH}\) of the solution. Calculate its \(\mathrm{pOH}\).

A 1000.-mL solution of hydrochloric acid has a pH of 1.3. Calculate the mass (g) of HCl dissolved in the solution.

The \(\mathrm{pH}\) of a \(\mathrm{Ba}(\mathrm{OH})_{2}\) solution is 10.66 at \(25^{\circ} \mathrm{C}\). Calculate the hydroxide ion concentration of this solution. If the solution volume is \(250 . \mathrm{mL},\) calculate the mass \((\mathrm{g})\) of \(\mathrm{Ba}(\mathrm{OH})_{2}\) that was used to make this solution.

The measured \(\mathrm{pH}\) of a sample of seawater is 8.30 . (a) Calculate the \(\mathrm{H}_{3} \mathrm{O}^{+}\) concentration. (b) Is the sample acidic or basic?

Acid \(A\) has \(K_{\mathrm{a}}=1 \times 10^{-5} ;\) Acid \(\mathrm{Z}\) has \(K_{\mathrm{a}}=5 \times 10^{-6}\) Base \(\mathrm{X}\) has \(K_{\mathrm{b}}=1 \times 10^{-4} ;\) Base \(\mathrm{Y}\) has \(K_{\mathrm{b}}=4 \times 10^{-5}\) (a) Which acid is the stronger acid? Explain your answer. (b) Which base is the stronger base? Explain your answer. (c) Which base has the stronger conjugate acid? Explain your answer. (d) Which acid has the weaker conjugate base? Explain your answer.

Leucine is an amino acid with this Lewis structure: Write the Lewis structure for the zwitterion form of leucine.

Write ionization equations and ionization constant expressions for these acids and bases. (a) \(\mathrm{CH}_{3} \mathrm{COOH}\) (b) \(\mathrm{HCN}\) (c) \(\mathrm{SO}_{3}^{2-}\) (d) \(\mathrm{PO}_{4}^{3-}\) (e) \(\mathrm{NH}_{4}^{+}\) (f) \(\mathrm{H}_{2} \mathrm{SO}_{4}\)

Write ionization equations and ionization constant expressions for these acids and bases. (a) \(\mathrm{F}^{-}\) (b) \(\mathrm{NH}_{3}\) (c) \(\mathrm{H}_{2} \mathrm{CO}_{3}\) (d) \(\mathrm{H}_{3} \mathrm{PO}_{4}\) (e) \(\mathrm{CH}_{3} \mathrm{COO}^{-}\) (f) \(S^{2-}\)

Which solution is more acidic? (a) \(0.10-\mathrm{M} \mathrm{H}_{2} \mathrm{CO}_{3}\) or \(0.10-\mathrm{M} \mathrm{NH}_{4} \mathrm{Cl}\) (b) \(0.10-\mathrm{M} \mathrm{HF}\) or \(0.10-\mathrm{M} \mathrm{KHSO}_{4}\) (c) \(0.1-\mathrm{M} \mathrm{NaHCO}_{3}\) or \(0.1-\mathrm{M} \mathrm{Na}_{2} \mathrm{HPO}_{4}\) (d) \(0.1-\mathrm{M} \mathrm{H}_{2} \mathrm{~S}\) or \(0.1-\mathrm{M} \mathrm{HCN}\)

Without doing any calculations, assign each of these 0.10-M aqueous solutions to one of these pH ranges: \(\mathrm{pH} 2 ; \mathrm{pH}\) between 2 and \(6 ; \mathrm{pH}\) between 6 and 8 \(\mathrm{pH}\) between 8 and \(12 ; \mathrm{pH} 12 .\) (a) \(\mathrm{HNO}_{2}\) (b) \(\mathrm{NH}_{4} \mathrm{Cl}\) (c) NaF (d) \(\mathrm{Mg}\left(\mathrm{CH}_{3} \mathrm{COO}\right)_{2}\) (e) \(\mathrm{BaO}\) (f) \(\mathrm{KHSO}_{4}\) (g) \(\mathrm{NaHCO}_{3}\) (h) \(\mathrm{BaCl}_{2}\)

Based on formulas alone, which is the stronger acid? (a) \(\mathrm{H}_{2} \mathrm{CO}_{3}\) or \(\mathrm{H}_{2} \mathrm{SO}_{4}\) (b) \(\mathrm{HNO}_{3}\) or \(\mathrm{HNO}_{2}\) (c) \(\mathrm{HClO}_{4}\) or \(\mathrm{H}_{2} \mathrm{SO}_{4}\) (d) \(\mathrm{H}_{3} \mathrm{PO}_{4}\) or \(\mathrm{HClO}_{3}\) (e) \(\mathrm{H}_{2} \mathrm{SO}_{2}\) or \(\mathrm{H}_{2} \mathrm{SO}\)

Based on formulas alone, classify each of the following oxoacids as strong or weak. (a) \(\mathrm{H}_{3} \mathrm{PO}_{4}\) (b) \(\mathrm{H}_{2} \mathrm{SO}_{4}\) (c) HClO (d) \(\mathrm{HClO}_{4}\) (e) \(\mathrm{HNO}_{3}\) (f) \(\mathrm{H}_{2} \mathrm{CO}_{3}\) (g) \(\mathrm{HNO}_{2}\)

Write balanced chemical equations that show phosphoric acid, \(\mathrm{H}_{3} \mathrm{PO}_{4}\), ionizing stepwise as a polyprotic acid.

Write stepwise chemical equations for protonation or deprotonation of each of these polyprotic acids and bases in water. (a) \(\mathrm{CO}_{3}^{2-}\) (b) \(\mathrm{H}_{3} \mathrm{AsO}_{4}\) (c) \(\mathrm{NH}_{2} \mathrm{CH}_{2} \mathrm{COO}^{-}\) (glycinate ion, a diprotic base)

Write stepwise chemical equations for protonation or deprotonation of each of these polyprotic acids and bases in water. (a) \(\mathrm{H}_{2} \mathrm{SO}_{3}\) (b) \(S^{2-}\) (c) \(\mathrm{NH}_{3} \mathrm{CH}_{3} \mathrm{COOH}^{+}\) (glycinium ion, a diprotic acid)

Write the ionization equation for a weak acid and the equation for its conjugate base reaction with water. Show that adding these two equations gives the autoionization equation for water.

Calculate the \(K_{\mathrm{a}}\) of butyric acid if a \(0.025-\mathrm{M}\) butyric acid solution has a pH of 3.21 .

The pH of a 0.10-M solution of propanoic acid, \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{COOH},\) a weak organic acid, is measured at equilibrium and found to be 2.93 at \(25^{\circ} \mathrm{C} .\) Calculate the \(K_{\mathrm{a}}\) of propanoic acid.

(a) Calculate the pH of a 0.050-M solution of benzoic acid, \(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{COOH} ; K_{\mathrm{a}}=1.2 \times 10^{-4}\) at \(25^{\circ} \mathrm{C}\) (b) Calculate the percent of the acid that has ionized in this solution.

Calculate the pH of a 0.12-M aqueous solution of the base aniline, \(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{NH}_{2} ; K_{\mathrm{b}}=3.9 \times 10^{-10}\).

Calculate the \(\left[\mathrm{OH}^{-}\right]\) and the \(\mathrm{pH}\) of a \(0.024-\mathrm{M}\) methylamine solution; \(K_{\mathrm{h}}=5.0 \times 10^{-4}\).