Question

Cellulose is water insoluble, despite its many OH groups. Considering its three-dimensional structure, why do you think this is so?

Short answer

Cellulose is water-insoluble as the hydroxyl groups (OH) present in it are not available to form hydrogen bonds with water molecules as they are present towards the inner part of the three-dimensional network of cellulose.

Step-by-step solution

Hydrogen bond

The electrostatic force of attraction between a hydrogen atom and an electronegative atom such as nitrogen, oxygen, or fluorine is termed a hydrogen bond.

Hydrogen bond and Solubility

Polar molecules are soluble in polar solvents and hydrogen bonds exist in polar molecules.

The more the number of hydrogen bonds in a molecule the more will be its solubility.

Solubility of cellulose

Cellulose is a three-dimensional structure consisting of long chains of glucose units in a three-dimensional (3D) arrangement.

The hydroxyl groups (OH) in cellulose are present in the interior of the three-dimensional structure and are unavailable for forming a hydrogen bond with water molecules.

Thus, the cellulose is water-insoluble as the hydroxyl groups do not participate in hydrogen bonding with the solvent molecules.