Hydrogen Bond - Hydrogen Bonding Phenomena

Hydrogen Bonding Phenomena

• Dramatically higher boiling points of NH₃, H₂O, and HF compared to the heavier analogues PH₃, H₂S, and HCl.
• Increase in the melting point, boiling point, solubility, and viscosity of many compounds can be explained by the concept of hydrogen bonding.
• Viscosity of anhydrous phosphoric acid and of glycerol
• Dimer formation in carboxylic acids and hexamer formation in hydrogen fluoride, which occur even in the gas phase, resulting in gross deviations from the ideal gas law.
• Pentamer formation of water and alcohols in apolar solvents.
• High water solubility of many compounds such as ammonia is explained by hydrogen bonding with water molecules.
• Negative azeotropy of mixtures of HF and water
• Deliquescence of NaOH is caused in part by reaction of OH− with moisture to form hydrogen-bonded H₃O−
  2 species. An analogous process happens between NaNH₂ and NH₃, and between NaF and HF.
• The fact that ice is less dense than liquid water is due to a crystal structure stabilized by hydrogen bonds.
• The presence of hydrogen bonds can cause an anomaly in the normal succession of states of matter for certain mixtures of chemical compounds as temperature increases or decreases. These compounds can be liquid until a certain temperature, then solid even as the temperature increases, and finally liquid again as the temperature rises over the "anomaly interval"
• Smart rubber utilizes hydrogen bonding as its sole means of bonding, so that it can "heal" when torn, because hydrogen bonding can occur on the fly between two surfaces of the same polymer.
• Strength of nylon and cellulose fibres.
• Wool, being a protein fibre is held together by hydrogen bonds, causing wool to recoil when stretched. However, washing at high temperatures can permanently break the hydrogen bonds and a garment may permanently lose its shape.