Question

Why is the boiling point of water much higher than expected based on the size of the molecule. Explain with a diagram ?

Answer 1

Hint: Water (\[{{H}_{2}}O\]) is an inorganic, clear, tasteless, odourless, and virtually colourless chemical substance that is the primary ingredient of the Earth's hydrosphere and all known living species' fluids (in which it acts as a solvent). Even though it contains no calories or organic nutrients, it is necessary for all known forms of life. Each of its molecules has one oxygen and two hydrogen atoms linked by covalent bonds, as indicated by its chemical formula \[{{H}_{2}}O\].

Complete answer:
The temperature at which a substance's vapour pressure equals the ambient pressure and vapour bubbles develop directly in the liquid is known as the boiling point. When the ambient pressure (and hence the vapour pressure of the BOILING LIQUID) is 1 atm, the usual boiling point is stated. Due to the presence of powerful and distinctive intermolecular interactions, the water molecule has an EXCEPTIONALLY high boiling point (when compared to molecules of comparable or even much greater size). The most important of these is hydrogen bonding, which occurs when hydrogen is bonded to a strongly electronegative element and causes electron density to polarise towards it.

Two hydrogen atoms and one oxygen atom make up a distinct water molecule. The most basic instance is a pair of water molecules connected by a single hydrogen bond, which is known as a water dimer and is frequently used as a model system. Because one water molecule's oxygen possesses two lone pairs of electrons, each of which can form a hydrogen bond with a hydrogen on another water molecule when more molecules are available, such as in liquid water, additional bonds are conceivable. This process can be repeated until every water molecule is H-bonded to at least four additional molecules (two through its two lone pairs, and two through its two hydrogen atoms).

Note:
Ice's crystal structure is highly influenced by hydrogen bonding, which aids in the formation of an open hexagonal lattice. Ice has a lower density than water at the same temperature, thus the solid phase of water, unlike most other things, floats atop the liquid.