A Simple Note on Properties of Hydrogen Bonding

The formation of hydrogen bonds, a sort of attractive intermolecular force induced by the dipole-dipole interaction between a hydrogen atom bonded to a strongly electronegative atom and another strongly electronegative atom nearby, is known as hydrogen bonding. The more electronegative oxygen atom in water molecules is covalently bonded to hydrogen (H2O).

Conditions required for Hydrogen Bonding

The hydrogen atom in the molecule needs to be linked with a strongly electronegative atom. A molecule’s electronegativity determines its polarisation.

It’s best if the electronegative atom is small. The smaller the size, the higher the electrostatic attraction.

Properties of Hydrogen Bonding

Compounds with hydrogen bonding between separate molecules have a higher boiling point, making them less volatile.

Lower alcohols are soluble in water due to hydrogen bonding between the water molecule and the alcohol molecule. Water molecules form a cage-like shape in solid ice due to hydrogen bonding. In fact, each water molecule is bonded to four other water molecules in a tetrahedral configuration. The molecules are not as closely packed in the solid state as they are in the liquid. As the ice melts, the case-like structure collapses, causing the molecules to become closer together. As a result, for the same amount of water, the volume of water decreases while the density increases. Ice does have a lower density than water at 273 K as a result of this. As a result, ice will float.

Viscosities and surface tension – In compounds with an attached molecule, hydrogen bonding occurs. As an outcome, the flow of their work gets more difficult. Surface tension is high, and viscosity is high.

How do hydrogen bonds affect solubility

Hydrogen atoms covalently linked to extremely electronegative elements are found in molecules capable of hydrogen bonding (O, N, F). A substance’s molecules are polar if they have hydrogen bonds between them. This indicates that the molecules are soluble in a polar solvent like water.

Ammonia (NH3) and methanol are two examples of polar molecules that hydrogen bond (CH3OH). Because of their polarity, these molecules dissolve in water.

CO2 is a nonpolar molecule with a linear structure that allows it to form hydrogen bonds with water. Carbon dioxide is much less soluble in water than polar molecules, implying that it is less soluble in water. When the water is cold, carbon dioxide solubility increases, but it decreases dramatically when the water is hot.

Volatile

“Volatile” usually refers to evaporation ease and high vapour pressure, and is thus a quality of a pure substance, whereas solubility is a property of a mixture of two or more substances.

Because charge imbalances are countered internally rather than by forging a contact with another molecule, an intramolecular hydrogen bond increases the volatility of a chemical.

Interactions among the substance’s molecules would reduce volatility, but intramolecular hydrogen bonds prohibit one molecule’s hydrogen bond giver and acceptor from engaging with another.

Density of ice less than water

Each oxygen atom in ice is surrounded by four hydrogen atoms in a tetrahedral arrangement, with two hydrogen atoms forming covalent bonds with each oxygen atom. At a distance of 1 Armstrong unit, these hydrogen atoms are closer to the oxygen atoms. Hydrogen atoms connect the remaining two hydrogen atoms to the centre atom. At 1.76 Armstrong units, they are 1.76 units apart from oxygen atoms. The corners of the tetrahedron contain the oxygen atoms of water molecules. The ice structure in the solid state extends in 3-D due to the tetrahedral arrangement of H2O molecules. Because hydrogen bonds between oxygen and H atoms are longer than covalent bonds, the molecules of H2O are not packed tightly, and there are empty spaces in the crystal structure. This results in an open cage-like structure for ice, which has a greater volume for the same mass of water. Ice has a lower density than water because of this.

Conclusion 

Due to the hydrogen in water molecules as a consequence of dipole-dipole interactions between one water molecule’s hydrogen atom and the oxygen atom from another H2O molecule.

In this situation, the O-H bond’s electron pair is quite close to the oxygen nucleus (because of the huge difference in the electronegativities of oxygen and hydrogen). As a result, the hydrogen atom produces a partial positive charge (+), while the oxygen atom produces a partial negative charge (-). Hydrogen bonding can now be formed through the electrostatic interaction of one water molecule’s hydrogen atom (with + charge) with the oxygen atom of some other water molecule (with – charge). As a result, hydrogen bonds are a special kind of intermolecular attraction that only happens when hydrogen atoms are bonded to a highly electronegative atom. Hydrogen bonds are very strong when compared to dipole-dipole and dispersion forces. However, they are weaker than covalent or ionic bonds.