Chapter 13

Write formulas for two salts that (a) contain \(\mathrm{NH}_{4}{\underline{\phantom{xx}}}^{+}\) and are basic. (b) contain \(\mathrm{CO}_{3}^{2-}\) and are basic. (c) contain \(\mathrm{Br}^{-}\) and are neutral. (d) contain \(\mathrm{ClO}_{4}^{-}\) and are acidic.

State whether \(1 M\) solutions of the following salts in water are acidic, basic, or neutral. (a) \(\mathrm{K}_{2} \mathrm{CO}_{3}\) (b) \(\mathrm{NH}_{4} \mathrm{~F}\) (c) \(\mathrm{LiH}_{2} \mathrm{PO}_{4}\) (d) \(\mathrm{NaNO}_{2}\) (e) \(\mathrm{Ba}\left(\mathrm{ClO}_{4}\right)_{2}\)

State whether \(1 M\) solutions of the following salts in water would be acidic, basic, or neutral. (a) \(\mathrm{FeCl}_{3}\) (b) \(\mathrm{BaI}_{2}\) (c) \(\mathrm{NH}_{4} \mathrm{NO}_{2}\) (d) \(\mathrm{Na}_{2} \mathrm{HPO}_{4}\) (e) \(\mathrm{K}_{3} \mathrm{PO}_{4}\)

Arrange the following \(0.1 M\) aqueous solutions in order of decreasing \(\mathrm{pH}\) (highest to lowest). \(\begin{array}{lllll}\mathrm{Ba}\left(\mathrm{NO}_{3}\right)_{2}, & \mathrm{HNO}_{3}, & \mathrm{NH}_{4} \mathrm{NO}_{3}, & \mathrm{Al}\left(\mathrm{NO}_{3}\right)_{3}, & \mathrm{NaF}\end{array}\)

Arrange the following \(0.1 M\) aqueous solutions in order of increasing pH (lowest to highest). \(\begin{array}{lllll}\mathrm{KOH}, & \mathrm{KF}_{3} & \mathrm{KCl}, & \mathrm{ZnCl}_{2}, & \mathrm{HCl}\end{array}\)

At \(25^{\circ} \mathrm{C}\), a \(0.20 \mathrm{M}\) solution of methylamine \(\left(\mathrm{CH}_{3} \mathrm{NH}_{2}\right)\) is \(5.0 \%\) ionized. What is \(K_{b}\) for methylamine?

Consider an acid HY (MM = \(100 \mathrm{~g} /\) mol [3 significant figures]). What is the \(\mathrm{pH}\) of a \(33.0 \%\) by mass solution of HY \((d=1.10 \mathrm{~g} / \mathrm{mL})\) ? The \(K_{n}\) of \(\mathrm{HY}\) is \(2.0 \times 10^{-8}\)

A student prepares \(455 \mathrm{~mL}\) of a KOH solution, but neglects to write down the mass of KOH added. His TA suggests that he take the \(\mathrm{pH}\) of the solution. The \(\mathrm{pH}\) is \(13.33 .\) How many grams of KOH were added?

Consider the process $$\mathrm{H}_{2} \mathrm{O} \rightleftharpoons \mathrm{H}^{+}(a q)+\mathrm{OH}^{-}(a q) \quad \Delta H^{\circ}=55.8 \mathrm{~kJ}$$ (a) Will the \(\mathrm{pH}\) of pure water at body temperature \(\left(37^{\circ} \mathrm{C}\right)\) be \(7.0 ?\) (b) If not, calculate the \(\mathrm{pH}\) of pure water at \(37^{\circ} \mathrm{C}\).

Consider a weak base, \(\mathrm{NaB}(\mathrm{MM}=281 \mathrm{~g} / \mathrm{mol})\). An aqueous solution of NaB has a \(\mathrm{pH}\) of \(8.73\) and an osmotic pressure of \(55 \mathrm{~mm} \mathrm{Hg}\) at \(25^{\circ} \mathrm{C}\). What is \(K_{b}\) for the weak base NaB?

Is a saline ( \(\mathrm{NaCl}\) ) solution at \(80^{\circ} \mathrm{C}\) acidic, basic, or neutral?

Which of the following is/are true about a \(0.10 \mathrm{M}\) solution of a strong acid, HY? (a) \(\left[\mathrm{Y}^{-}\right]=0.10 \mathrm{M}\) (b) \([\mathrm{HY}]=0.10 \mathrm{M}\) (c) \(\left[\mathrm{H}^{+}\right]=0.10 \mathrm{M}\) (d) \(\mathrm{pH}=1.0\) (c) \(\left[\mathrm{H}^{+}\right]+\left[\mathrm{Y}^{-}\right]=0.20 \mathrm{M}\)

Consider the following six beakers. All have \(100 \mathrm{~mL}\) of aqueous \(0.1 \mathrm{M}\) solutions of the following compounds: beaker A has HI beaker B has \(\mathrm{HNO}_{2}\) beaker \(\mathrm{C}\) has \(\mathrm{NaOH}\) beaker \(\mathrm{D}\) has \(\mathrm{Ba}(\mathrm{OH})_{2}\) beaker \(\mathrm{E}\) has \(\mathrm{NH}_{4} \mathrm{Cl}\) beaker \(\mathrm{F}\) has \(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{NH}_{2}\)

What is the \(\mathrm{pH}\) of a \(0.200 \mathrm{M}\) solution of \(\mathrm{H}_{2} \mathrm{SO}_{4}\) ? You may assume that the first ionization is complete. The second ionization constant is \(0.010\).

Using the Tables in Appendix 1, calculate \(\Delta H\) for the reaction of the following. (a) \(1.00 \mathrm{~L}\) of \(0.100 \mathrm{M} \mathrm{NaOH}\) with \(1.00 \mathrm{~L}\) of \(0.100 \mathrm{M} \mathrm{HCl}\) (b) \(1.00 \mathrm{~L}\) of \(0.100 \mathrm{M} \mathrm{NaOH}\) with \(1.00 \mathrm{~L}\) of \(0.100 \mathrm{M}\) HF, taking the heat of formation of \(\mathrm{HF}(a q)\) to be \(-320.1 \mathrm{~kJ} / \mathrm{mol}\)

Show by calculation that when the concentration of a weak acid decreases by a factor of 10 , its percent ionization increases by a factor of \(10^{1 / 2}\).

What is the freezing point of vinegar, which is an aqueous solution of \(5.00 \%\) acetic acid, \(\mathrm{HC}_{2} \mathrm{H}_{3} \mathrm{O}_{2}\), by mass \(\left(d=1.006 \mathrm{~g} / \mathrm{cm}^{3}\right) ?\)

The solubility of \(\mathrm{Ca}(\mathrm{OH})_{2}\) at \(25^{\circ} \mathrm{C}\) is \(0.153 \mathrm{~g} / 100 \mathrm{~g} \mathrm{H}_{2} \mathrm{O}\). Assuming that the density of a saturated solution is \(1.00 \mathrm{~g} / \mathrm{mL}\), calculate the maximum \(\mathrm{pH}\) one can obtain when \(\mathrm{Ca}(\mathrm{OH})_{2}\) is dissolved in water.