Calculate the molar solubility of zinc tetrathiocyanato-N-mercurate (II) if its $\mathrm{K}_{\mathrm{sp}}=2…

Calculate the molar solubility of zinc tetrathiocyanato-N-mercurate (II) if its $\mathrm{K}_{\mathrm{sp}}=2.2 \times 10^{-7}$
  1. $0.00380$
  2. $0.000469$
  3. $0.0095$
  4. $0.0183$

Solution

The equilibrium reaction is as shown below,
$\mathrm{Zn}\left[\mathrm{Hg}(\mathrm{NCS})_{4}ight] ightleftharpoons \mathrm{Zn}^{+2}+\left[\mathrm{Hg}(\mathrm{NCS})_{4}ight]^{2-}$
The expression for the solubility product is
$\mathrm{K}_{\mathrm{sp}}=\left[\mathrm{Zn}^{+2}ight]\left[\left[\mathrm{Hg}(\mathrm{NCS})_{4}ight]^{2-}ight]$
Let S moles per litre be the molar solubility.
$\Rightarrow \mathrm{K}_{\mathrm{sp}}=\mathrm{S}^{2}$
$\Rightarrow \mathrm{S}=\sqrt{22 \times 10^{-8}}=4.69 \times 10^{-4} \mathrm{~mol} / \mathrm{L}$ ^

Asked in: JEE-TOPICTESTS-CHEMISTRY

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