Question

The correct order of ${\mathrm{K}}_{\mathrm{b}}$ value of the following is

• A. 1 > 2 > 3
• B. 1 > 3 > 2
• C. 3 > 2 > 1
• D. 3 > 1 > 2

Answer 1

The correct option is B

1 > 3 > 2

The correct option is (B):

Explanation for the correct answer:

Basic strength:-

1. It is basically defined as the condition of being a base or it can also be determined as the difficulty of an acid to react with a particular base.
2. Basicity can also be known as the Stability of the lone pair electrons.
3. Basically amines are basic in nature just because of the presence of the unshared electrons, and these electrons will create an electron density around the Nitrogen atom.
4. It is actually influenced by the $+\mathrm{I}$ effect and the solvation by water, as such the solvent water will stabilize the conjugate acid by the Hydrogen bonding.
5. Generally, basicity increases with the increasing negative charges that are present on the Nitrogen atom, also the resonance stabilized amines are less basic if compared.
6. Basicity also gets decreased with the $-\mathrm{I}$effect as well as basicity increases with the decreasing s-character.
7. $\mathrm{Kb}\propto \mathrm{Basic}\mathrm{strength}.$
8. So, $\mathrm{Basic}\mathrm{strength}\propto \mathrm{amount}\mathrm{of}\mathrm{hydration}\propto \mathrm{Availability}\mathrm{of}\mathrm{Lone}\mathrm{Pairs}\mathrm{on}\mathrm{Nitrogen}.$
9. Hence, combining both effects the order of Basic strength is: $2°>3°>{\mathrm{NH}}_3$.

Therefore, the correct answer is (B):- 1 > 3 > 2.