Applications of Solubility Product and Common Ion Effect

$\frac{\mathrm{x}}{20}\mathrm{M}$ concentration of ${\mathrm{H}}^{+}$ ion must be maintained in a saturate ${\mathrm{H}}_2\mathrm{S}\left(0.1\mathrm{M}\right)$ to precipitate $\mathrm{C}\mathrm{d}\mathrm{S}$ but not $\mathrm{Z}\mathrm{n}\mathrm{S}$ , if $[{\mathrm{Cd}}^{2+}]=[{\mathrm{Zn}}^{2+}]=0.1\mathrm{M}$ initially. ${\mathrm{K}}_{\mathrm{s}\mathrm{p}}(\mathrm{CdS})=8\times 10^{-27},\mathrm{}{\mathrm{K}}_{\mathrm{s}\mathrm{p}}\left(\mathrm{Z}\mathrm{n}\mathrm{S}\right)=1\times {10}^{-21}{\mathrm{K}}_{\mathrm{a}}\left({\mathrm{H}}_2\mathrm{S}\right)=1\times {10}^{-21}$ . $\mathrm{Z}\mathrm{n}\mathrm{S}$ will not precipitate at a concentration of ${\mathrm{H}}^{+}$ greater than $\frac{\mathrm{x}}{20}\mathrm{M}$ . The value of $\mathrm{x}$ is.

The presence of $N{H}_{4}Cl$ in the test solution while precipitating group III-A hydroxides (in qualitative inorganic analysis) helps in

Which of the following mixture cannot be separated by passing ${\mathrm{H}}_2\mathrm{S}$ through their solutions containing dilute $\mathrm{HCl}$?

Which of the sulphides is yellow?

The solubility products of $\mathrm{Al}(\mathrm{OH}{)}_3$ and $\mathrm{Zn}(\mathrm{OH}{)}_2$ are $8.5 \times {10}^{-23}$ and $1.8 \times {10}^{-14}$ respectively. If ${\mathrm{NH}}_4\mathrm{OH}$ is added to a solution containing ${\mathrm{Al}}^{3+}$ and ${\mathrm{Zn}}^{2+}$ ions, then the substance precipitated first is:

What concentration of${\mathrm{NH}}_3$ must be present in a$0.1\mathrm{M} {\mathrm{AgNO}}_3$ solution to prevent$\mathrm{AgCl}$ from precipitating, when $4.0 \mathrm{g}$ of$\mathrm{NaCl}$ is added to a $250 \mathrm{mL}$ of this solution.$({\mathrm{K}}_{\mathrm{s}\mathrm{p}}=2\times {10}^{-10}$, ${\text{K}}_{\text{f}}\left[\text{Ag}{\left({\text{NH}}_3\right)}_2^{+}\right]=10^7)$

Calculate the equilibrium concentrations of each of the indicated species necessary to reduce an initial$0.2 \mathrm{M} {\mathrm{Zn}}^{2+}$solution to $1.0 \mathrm{x} {10}^{-4} {\mathrm{Zn}}^{2+}$.

(i)  ${\text{NH}}_3\& \text{Zn}{\left({\text{NH}}_3\right)}_4^{2+}$  (assume no partial complexation)
(ii)  $\stackrel{\ominus }{\text{O}}\text{H}$  in equilibrium with $\text{Zn}{\left(\text{OH}\right)}_2\left(\text{s}\right)$.
(iii)  $\stackrel{\ominus }{\text{O}}\text{H}\&\text{Zn}{\left(\text{OH}\right)}_4^{2-}$.
(iv)  Calculate  $\left[\stackrel{\ominus }{\text{O}}\text{H}\right]$  which would be produced by each equilibrium concentration of${\mathrm{NH}}_3$.
(v)  Explain what would be observed if concentrated ${\mathrm{NH}}_3$ solution were added slowly to $0.2 \mathrm{M}$ solution of ${\text{Zn}}^{2+}$.
Given.    ${\text{K}}_{\text{f}}\text{ Zn }{{\left({\text{NH}}_3\right)}_4}^{2+}=5\times 10^8$.
                  ${\text{K}}_{\text{sp}}\text{ Zn}{\left(\text{OH}\right)}_2=1\text{.}8\times 10^{-14}$.
                  ${\text{K}}_{\text{f}}\text{ Zn}{{\left(\text{OH}\right)}_4}^{2-}=5\times 10^{14}$,
                ${\text{K}}_{\text{b}}{\text{ NH}}_4\text{OH}=1\text{.}8\times 10^{-5}$ .

A solution has $0.05 \mathrm{M} {\mathrm{Mg}}^{2+}$ and $0.05 \mathrm{M} {\mathrm{NH}}_3$. Calculate the concentration of ${\mathrm{NH}}_4\mathrm{Cl}$ required to prevent the formation of$\mathrm{Mg}(\mathrm{OH}{)}_2$ in solution. $({\mathrm{K}}_{\mathrm{sp}} \mathrm{Mg}(\mathrm{OH}{)}_2 = 9 \times {10}^{-12}$ and ionization constant of ${\mathrm{NH}}_3 \mathrm{is} 1.8 \times {10}^{-5})$.   

(i)  Will a precipitate of $\mathrm{Mg}(\mathrm{OH}{)}_2$ be formed in a $0.001 \mathrm{M}$ solution of $\mathrm{Mg}({\mathrm{NO}}_3{)}_2$ if the $\mathrm{pH}$ of solution is adjusted to $9$. $({\mathrm{K}}_{\mathrm{sp}} \mathrm{of} \mathrm{Mg}(\mathrm{OH}{)}_2=8.9 \mathrm{x} {10}^{{}_{-12}})$ .

(ii)  Calculate $\mathrm{pH}$ at which $\mathrm{Mg}(\mathrm{OH}{)}_2$ begin to precipitate from a solution containing $0.1 \mathrm{M} {\mathrm{Mg}}^{2+}$ ions. $({\mathrm{K}}_{\mathrm{sp}} \mathrm{of} \mathrm{Mg}(\mathrm{OH}{)}_2=1.0 \mathrm{x} {10}^{{}_{-11}})$.

(iii)  Calculate $\left[\stackrel{\ominus }{\text{O}}\text{H}\right]$  of a solution after $100 \mathrm{mL}$ of $0.1 \mathrm{M} {\mathrm{MgCl}}_2$ is added to $100 \mathrm{mL}$ of $0.2 \mathrm{M} \mathrm{NaOH}$. $({\mathrm{K}}_{\mathrm{sp}} \mathrm{of} \mathrm{Mg}(\mathrm{OH}{)}_2=1.2 \mathrm{x} {10}^{{}_{-11}})$ .

Determine the molar solubility of ${\mathrm{CaCO}}_3 ( \mathrm{in} {10}^{-5} \mathrm{M} \mathrm{units} )$ in a buffer solution of $\mathrm{pH} 8.5. ({\mathrm{K}}_{\mathrm{sp}} = 2.8 \mathrm{x} {10}^{-9} \mathrm{and} \mathrm{of} {\mathrm{CO}}_2 \mathrm{is} 4.7 \mathrm{x} {10}^{-11} )$

A solution of $0.1\mathrm{M}$ in ${\mathrm{Cl}}^{-}$ and ${10}^{-4}\mathrm{M} {{\mathrm{CrO}}_4}^{2-}$. If solid ${\mathrm{AgNO}}_3$ is gradually added to this solution, what will be the concentration of ${\mathrm{Cl}}^{-}$ when ${\mathrm{Ag}}_2{\mathrm{CrO}}_4$ begins to precipitate? $\left[{\mathrm{K}}_{\mathrm{sp}} \left(\mathrm{AgCl}\right)={10}^{-10}{\mathrm{M}}^2; {\mathrm{K}}_{\mathrm{sp}} \left({\mathrm{AgCr}}_2{\mathrm{O}}_4\right)={10}^{-12}{\mathrm{M}}^3\right]$