Question

Which of the following is soluble in organic solvents like ethanol?
A.LiCl
B.NaCl
C.KCl
D.RbCl

Answer 1

Hint: To solve this question, we must first understand that only covalent solutes are capable of dissolving in organic solvents. From the given options, we must hence find the compound with the highest covalent character.

Complete Step-by-Step Answer:
Before we move forward with the solution of the given question, let us first understand some important basic concepts.
The nature of the bond formed between two atoms can be determined on the basis of Fajan’s Rule. By the nature of the bond, we mean whether the bond formed is covalent or ionic in nature. Fajan’s Rule is based on 2 major characteristics:
1.The size of the ions involved: Larger size of the anion and smaller size of the cation, would influence the ionic bond between the elements formed to exhibit grater covalent nature.
2.Charges on the ions involved: The covalent character of the ionic bond is directly dependent on the charge on the cation. This means that higher charge on the cation would influence the ionic bond to be more covalent
Now you must be wondering why we are discussing the covalent characters of ionic bonds. The reason for this is that only covalent solids have the capability of being dissolved in organic solvents like ethanol. Now let us discuss the options given to us.
All the ionic compounds present have one common anion – chlorine. Hence the size of the cation would determine the covalent character of the compound.
If we look in the periodic table, Lithium is placed at the top of group 1 and all the other cations mentioned below are placed at lower positions. Hence, the size of the atom of Lithium is the smallest as compared with the other cations in the options. Hence, LiCl has the highest covalent character.
Hence, LiCl is soluble in organic solvents like ethanol.

Hence, Option A is the correct option

Note: The reason why ionic solutes are not soluble in organic compounds is their polar nature. Polar compounds cannot combine with non – polar compounds due to the polarisation of the atoms. And as you guessed it, organic compounds are non – polar in nature.