Question

LiCl and ${\text{MgC}}{{\text{l}}_2}$ dissolve in alcohol. How do you explain this?

Answer 1

Hint: Polar compounds dissolve in the polar solvent because charged ions of the polar compounds get stabilization by charged ions of solvent. Nonpolar compounds dissolve in nonpolar solvent due to similar interaction of solute-solute, solvent-solvent, and solute-solvent.

Complete answer :
The bond between metal and non-metal is known as an ionic bond. Lithium and magnesium are metal and chlorine are non-metal, so lithium chloride and magnesium chloride both are ionic compounds.
Lithium chloride is an ionic compound but it also has some covalent character due to the very small size of lithium metal. Due to polar nature lithium chloride is soluble in a polar solvent. Magnesium chloride is also an ionic compound. Due to polar nature, it is also soluble in a polar solvent.

Polar compounds are soluble in a polar solvent and non-polar compounds are soluble in a nonpolar solvent. The formula of alcohol is ${{\text{H}}_{\text{3}}}{\text{C}} - {\text{C}}{{\text{H}}_2} - {\text{OH}}$. Alcohol forms hydrogen bonding and it also has a covalent character, so it is a polar solvent.

So, due to polar nature lithium chloride and magnesium chloride are soluble in polar solvent alcohol.

Note: The covalent character in ionic compounds is determined by using Fajan’s rule. According to Fajan’s rule, the covalent character in ionic compounds are directly proportional to the polarizing power of the cation and inversely proportional to the polarizability of the anion. The polarizing power of the cation is high if the size is small and the charge is maximum. The polarizability of the anion will be high if the size is large and the charge is maximum.