Question

Arrange the following in the decreasing order of solubility in water :

i) $C_6{H}_5{NH}_2$

ii) $(C_2{H}_5{)}_{2}NH$

iii) $C_2{H}_5{NH}_2$

• A. i > ii > iii
• B. ii > i > iii
• C. iii > i > ii
• D. iii > ii > i

Answer 1

The correct option is D iii > ii > i

Ethylamine when added to water forms intermolecular H−bonds with water. And therefore it is most soluble in water.

Diethylamine having a bigger alkyl chain forms weaker intermolecular hydrogen bonds.

But aniline does not form H−bond with water to a very large extent due to the presence of a large hydrophobic $-C_6{H}_5$ group. Hence, aniline has the least solubility in water.

Hence the order of solubility is $iii>ii>i$