Question

Expression for ${K_{sp}}$ of $H{g_2}{(N{O_3})_2}$ is:
A. ${[H{g^ + }]^2}{[NO_3^ - ]^2}$
B. ${[Hg_2^ + ]^2}{[NO_3^ - ]^2}$
C. $[Hg_2^{2 + }]{[NO_3^ - ]^2}$
D. ${[Hg_2^{2 + }]^2}{[NO_3^ - ]^2}$

Answer 1

Hint:The solubility product constant represents the maximum extent to which the solid component can dissociate when dissolved in the solution. In solubility product constant the concentration of products are multiplied.

Complete step by step answer:Mercury(I) nitrate is a chemical compound having a molecular formula $H{g_2}{(N{O_3})_2}$.
Mercury (I) nitrate is formed from the reaction of mercury with dilute nitric acid.
The solution formed from mercury (I) nitrate is acidic in nature as it shows slow reaction with water and on reacting in water it forms a yellow precipitate of $H{g_2}(N{O_3})OH$.
The reaction is shown below.
$H{g_2}{(N{O_3})_2} + {H_2}O \to H{g_2}(N{O_3})OH + HN{O_3}$
The ${K_{sp}}$ of the solution is known as the solubility product constant which is an equilibrium constant for the solid substances which dissolve in aqueous medium. The solubility product constant represents the stages at which the solid compound dissolves in the aqueous solution.
For higher value of solubility product constant, the higher soluble should be the compound.
The general dissociation reaction is shown below.
$aA(s) \to cC(aq) + dD(aq)$
To solve the solubility product constant, the concentration of the products are multiplied and if there is any coefficient present in front of the product then the product is raised with the coefficient power.
The solubility product constant of above reaction is shown below.
${K_{sp}} = {[C]^c}{[D]^d}$
The dissociation of mercury (I) nitrate $H{g_2}{(N{O_3})_2}$ is shown below.
$H{g_2}{(N{O_3})_2} \rightleftharpoons Hg_2^{2 + } + 2NO_3^ -$
Thus, the solubility product constant will be as shown below.
${K_{sp}} = [Hg_2^{2 + }]{[NO_3^ - ]^2}$
Therefore, the correct option is C.

Note: Mercury on reaction with concentrated nitric acid will yield mercury (II) nitrate. The reactant is not included in the expression of solubility product constant. The solid compounds are not included in the calculation of equilibrium constant equation as the solids concentration does not change expression.