Question

The solubility of $Hg{{I}_{2}}$ in water decreases in presence of KI.
State whether the given statement is true or false.
A.True
B.False

Answer 1

The solubility of any chemical in water is going to depend on the ionization of the particular molecule. If any molecule converts easily into ions when they are added to water they have good solubility and if the molecule don’t convert into ions when added to water has less solubility or in-soluble in water.

Complete answer:
Mercury Iodide is a chemical compound having a molecular formula of$Hg{{I}_{2}}$.
Mercury Iodide is prepared synthetically but can also be found in nature as a rare mineral called coccinite.
Mercury Iodide is hardly soluble in water or less soluble in water (<100ppm).
When we are going to add KI (Potassium Iodide) to $Hg{{I}_{2}}$the following reaction takes place.
$Hg{{I}_{2}}+2KI\to {{K}_{2}}Hg{{I}_{4}}$
In the above reaction $Hg{{I}_{2}}$reacts with two moles of potassium iodide and forms a salt with a chemical formula${{K}_{2}}Hg{{I}_{4}}$.
${{K}_{2}}Hg{{I}_{4}}$is a complex formed by the addition of KI to $Hg{{I}_{2}}$.
${{K}_{2}}Hg{{I}_{4}}$is a salt containing two potassium ions, one mercury and four iodide ions.
Due to the salt nature of ${{K}_{2}}Hg{{I}_{4}}$it is soluble in water.
Therefore by the addition of KI the solubility of $Hg{{I}_{2}}$increases in water due to the formation of salt.

So, the given statement is False (B).

Note:
The solubility of few chemicals in water will be increased by making them as salts or complexes by the addition of a suitable chemical. Sometimes the solubility will be decreased due to the common ion effect.