Question

The maximum number of hydrogen bonds formed by a water molecule in ice is:
A. 4
B. 1
C. 2
D. 3

Answer 1

Hint: Water, in liquid form forms less hydrogen bonds as compared to ice. In the liquid form of water, the thermal energy breaks some bonds.

Complete step by step answer:
Hydrogen bonding is a special type of dipole-dipole attraction between molecules. It results from the attractive force between a hydrogen atom covalently bonded to a very electronegative atom such as a N, O, or F atom and another very electronegative atom. Hydrogen bond strengths range from 4 kJ to 50 kJ per mole of hydrogen bonds. Because of the difference in electronegativity, the H atom bears a large partial positive charge and the other electronegative atom bears a partial negative charge. So, the H atom is electrostatically attracted to the other electronegative atom. Hydrogen bonds have about a tenth of the strength of an average covalent bond, and are being constantly broken and reformed.
Each water molecule can form two hydrogen bonds involving their hydrogen atoms plus two further hydrogen bonds by their oxygen atom. These four hydrogen bonds arrange themselves tetrahedrally in ice. However, in liquid water, thermal energy bends and stretches and sometimes breaks these hydrogen bonds. On an average, a liquid water molecule is hydrogen bonded to approximately 3.4 other water molecules and in ice, each molecule is hydrogen bonded to 4 other molecules.

Hence, the correct answer is (A) 4.

Note: However, the hydrogen bonding in liquid water is not perfect and is disturbed by thermal agitation, the average structure of the hydrogen bonded liquid water is also a tetrahedron.