JEE Chemistry 2023 Question with Solution

Given: An ice crystal structure of water.

Find: The number of neighbouring molecules to which each water molecule is hydrogen bonded.

In an ice crystal, each water molecule forms four hydrogen bonds with its neighboring water molecules.

A water molecule, $\mathrm{H_2O}$, has two hydrogen atoms and one oxygen atom. The oxygen atom is more electronegative than hydrogen, creating a polar molecule with a partial negative charge on oxygen and partial positive charges on the hydrogens.

Each water molecule can act as a hydrogen bond donor through its two hydrogen atoms, forming two hydrogen bonds.

Additionally, each water molecule can act as a hydrogen bond acceptor through its two lone pairs on oxygen, forming two more hydrogen bonds.

Therefore, each water molecule in ice participates in a total of four hydrogen bonds: two as a donor and two as an acceptor, creating a tetrahedral network structure.

Thus, each water molecule is hydrogen bonded to $4$ neighbouring molecules.

Given: The arrangement of water molecules in an ice crystal.

Find: How many neighbouring molecules are hydrogen bonded to one water molecule.

From the diagram, the central water molecule is connected through hydrogen bonds to four surrounding water molecules.

This corresponds to the tetrahedral arrangement present in ice.

Hence, the required number is $4$.