Hydrogen bonding: The force of attraction between hydrogen atom and strong electronegative atoms such as Flourine,Hydrogen or Nitrogen is called hydrogen bonding
Properties: (1). Hydrogen bond is stronger than dipole dipole interaction but weaker than covalent bond.It is approximately twenty times weaker than covalent bond
(2). Hydrogen bond is directional.
(3). Hydrogen bond results in the formation of long chains and networks of molecules
Applications: There are alots of applications of hydrogen bond some are given below
1)Strenght of Acids: There is inversely relationship between acidity of molecules and hydrogen bond strenght. Greater the strenght of hydrogen bonding then lower will be its acidity and vice versa
So HF is weaker acid than HCl,HBr and HI because the hydrogen atom is entrapped between two highly electronegative atom in HF due to hydrogen bonding
2).Solubility: Thos substances which can form hydrogen bonds with water molecules are soluble in water forexample ethyl alcohol.
3).Cleansing Action: Soaps and detergents are made up of long non polar hydrocarbons tail and a polar anion(head) In water anionic head is stabilized by hydrogen bond with water molecules .While the non polar tail remains outside of water(polar molecule) because it is not soluble in water.Thus,hydrogen bondings help in cleansing action of soap and detergents.
4).In Biological compounds : Large protein molecules in living organization are stabilized by hydrogen bonding.Fibers,hairs and muscle proteins are composed of long chain of amino acids.these chains are around each other and form a spiral helix.Hydrogen bonds stabilize these spiral helix.
5).DNA in cell: DNA(deoxyribonucleic acid) has two spiral strands of RNA which are coiled about a common axis.They form a double helix ladder type structure.The steps of this ladder having different nitrogenous bases are attached by hydrogen bonds.
6).Paints and dyes: The adhesive nature of certain paints and dyes is also due to hydrogen bondings.Similarly,sticky action of glue and honey is due to hydrogen bonding
7).Food materials: Food materials such as carbohydrates e.g glucose,fructose and sucrose are stabilized due to hydrogen bondings.These all having OH group which form hydrogen bonding.
8).Structure of ice: In liquid water, molecules form hydrogen bonding with each other.But due to mobile action of molecules,bonds are formed and reformed.Hence there is lesz regularity and less free space.However,when temperature of H2O is lowered below 4°C , its molecules become regular and form permanent hydrogen bonds.Thus empty spaces are developed in between the molecules.As a result, its volume increases and ice occupies more space than liquid water.Therefore, density of ice becomes less than water and it floats over water..