Chapter 18

A handbook lists the solubility of ${\mathrm{CaHPO}}_4$ as $0.32\mathrm{g}$ ${\mathrm{CaHPO}}_4\cdot 2{\mathrm{H}}_2\mathrm{O}/\mathrm{L}$ and lists $K_{\mathrm{sp}}$ as $1\times {10}^{-7}$. (a) Are these data consistent? (That is, are the molar solubilities the same when derived in two different ways?) (b) If there is a discrepancy, how do you account for it?

What percentage of the ${\mathrm{Ba}}^{2+}$ in solution is precipitated as ${\mathrm{BaCO}}_3(\mathrm{s})$ if equal volumes of $0.0020\mathrm{M}{\mathrm{Na}}_2{\mathrm{CO}}_3(\mathrm{aq})$ and $0.0010\mathrm{M}{\mathrm{BaCl}}_2(\text{ aq })$ are mixed?

Determine the molar solubility of lead(II) azide, $\mathrm{Pb}{\left({\mathrm{N}}_3\right)}_2,$ in a buffer solution with $\mathrm{pH}=3.00,$ given that $\mathrm{Pb}{\left({\mathrm{N}}_3\right)}_2(\mathrm{s})\rightleftharpoons {\mathrm{Pb}}^{2+}(\mathrm{aq})+2{\mathrm{N}}_3^{-}(\mathrm{aq})$ $K_{\mathrm{sp}}=2.5\times {10}^{-9}$ ${\mathrm{HN}}_3(\mathrm{aq})+{\mathrm{H}}_2\mathrm{O}(\mathrm{l})\rightleftharpoons {\mathrm{H}}_3{\mathrm{O}}^{+}(\mathrm{aq})+{\mathrm{N}}_3^{-}(\mathrm{aq})$ $K_{\mathrm{a}}=1.9\times {10}^{-5}$

Calculate the molar solubility of $\mathrm{Mg}(\mathrm{OH}{)}_2$ in $1.00\mathrm{M}$ ${\mathrm{NH}}_4\mathrm{Cl}(\mathrm{aq})$.

The chief compound in marble is ${\mathrm{CaCO}}_3$. Marble has been widely used for statues and ornamental work on buildings. However, marble is readily attacked by acids. Determine the solubility of marble (that is, $\left[{\mathrm{Ca}}^{2+}\right]\text{ in a saturated solution })$ in (a) normal rainwater of $\mathrm{pH}=5.6;$ (b) acid rainwater of $\mathrm{pH}=4.20.$ Assume that the overall reaction that occurs is ${\mathrm{CaCO}}_3(\mathrm{s})+{\mathrm{H}}_3{\mathrm{O}}^{+}(\mathrm{aq})\rightleftharpoons$ ${\mathrm{Ca}}^{2+}(\mathrm{aq})+{\mathrm{HCO}}_3^{-}(\mathrm{aq})+{\mathrm{H}}_2\mathrm{O}(1)$

What is the solubility of $\mathrm{MnS}$, in grams per liter, in a buffer solution that is $0.100\mathrm{M}{\mathrm{CH}}_3\mathrm{COOH}-0.500\mathrm{M}$ ${\mathrm{NaCH}}_3\mathrm{COO}?$ For $\mathrm{MnS},K_{\mathrm{spa}}=3\times {10}^7$.

Write net ionic equations for each of the following observations. (a) When concentrated ${\mathrm{CaCl}}_2(\mathrm{aq})$ is added to ${\mathrm{Na}}_2{\mathrm{HPO}}_4(\mathrm{aq}),$ a white precipitate forms that is $38.7\mathrm{\%}$ Ca by mass. (b) When a piece of dry ice, ${\mathrm{CO}}_2(\mathrm{s}),$ is placed in a clear dilute solution of limewater $[\mathrm{Ca}(\mathrm{OH}{)}_2(\mathrm{aq})]$, bubbles of gas evolve. At first, a white precipitate forms, but then it redissolves.

Reaction (18.10), described in the Integrative Example, is called a carbonate transposition. In such a reaction, anions of a slightly soluble compound (for example, hydroxides and sulfates) are obtained in a sufficient concentration in aqueous solution that they can be identified by qualitative analysis tests. Suppose that $3\mathrm{M}{\mathrm{Na}}_2{\mathrm{CO}}_3$ is used and that an anion concentration of $0.050\mathrm{M}$ is sufficient for its detection. Predict whether carbonate transposition will be effective for detecting (a) ${\mathrm{SO}}_4^{2-}$ from ${\mathrm{BaSO}}_4(\mathrm{s});$ (b) ${\mathrm{Cl}}^{-}$ from $\mathrm{AgCl}(\mathrm{s});(\mathrm{c}){\mathrm{F}}^{-}$ from ${\mathrm{MgF}}_2(\mathrm{s})$.

The solubility of $\mathrm{AgCN}(\mathrm{s})$ in $0.200\mathrm{M}{\mathrm{NH}}_3(\mathrm{aq})$ is $8.8\times {10}^{-6}\mathrm{mol}/\mathrm{L}.$ Calculate $K_{\mathrm{sp}}$ for $\mathrm{AgCN}$.

The solubility of ${\mathrm{CdCO}}_3(\mathrm{s})$ in $1.00\mathrm{M}\mathrm{KI}(\mathrm{aq})$ is $1.2\times {10}^{-3}\mathrm{mol}/\mathrm{L}.$ Given that $K_{\mathrm{sp}}$ of ${\mathrm{CdCO}}_3$ is $5.2\times {10}^{-12},$ what is $K_{\mathrm{f}}$ for ${\left[{\mathrm{CdI}}_4\right]}^{2-}?$