Question

The intramolecular hydrogen bonding in compound leads to:
(a) Less boiling point and high solubility in water
(b) Less boiling point and low solubility in water
(c) High boiling point and low solubility in water
(d) High boiling point and high solubility in water

Answer 1

Hint: Hydrogen bonding: The force of attraction between, the positively charged hydrogen atom of one molecule and the electronegative atom of another molecule is known as hydrogen bonding. Intramolecular hydrogen bonding: When the hydrogen bonding is formed among the positively and negatively charged parts of the same molecule, then it is termed as Intramolecular hydrogen bonding. For example: o-nitrophenol.

Complete answer:
The molecules having intramolecular bonding are bound together with themselves with a stronger force of attraction. The force of attraction of hydrogen cation and respective negative anion of the molecule is high. Thus, when they try to dissolve in water, they do not break their hydrogen bond easily. Hence, the solubility of an intramolecular hydrogen bond is very low.
We know that the melting point, and boiling point of a molecule depends on the bond between two molecules. That is, the melting point and boiling points does not change with the formation or breaking of intramolecular hydrogen bonds. Thus, there is no elevation in the boiling point of the compound. Hence, the boiling point of the intramolecular compounds is very less. Therefore, intra-molecular compounds have low solubility in water, and low boiling and melting points.

This implies, option (B) is correct.

Note: It should be noted that, Intermolecular Hydrogen Bonding is among the two distinct molecules of a compound, while Intramolecular Hydrogen Bonding is between electropositive hydrogen of one molecule and electronegative atom of the same molecule. A compound may have both, Intermolecular, and Intramolecular hydrogen bonding as well. You must be able to differentiate between both the cases.