Water and Biomolecules: A Comprehensive Study Guide

Higher Physical Properties: Water exhibits significantly higher melting point, boiling point, and heat of vaporization compared to most other solvents. These properties are attributable to hydrogen bonds.
Nature of Hydrogen Bonds (H-bonds):
- Primarily electrostatic attractions.
- Relatively weak individually, approximately -23 ext{kJ/mol} compared to covalent bonds.
- Fleeting, with a typical lifetime of (1-20 ext{ps}).
Comparison of Liquid Water and Ice:
- Ice: Each water molecule forms 4 hydrogen bonds, creating a rigid lattice.
- Liquid Water: Each water molecule forms an average of 3.4 hydrogen bonds, allowing for dynamic movement and flexibility.
Thermodynamics of Phase Changes (at room temperature):
- Melting:The transition from solid to liquid occurs when molecular vibrations increase with added heat, breaking hydrogen bonds and allowing ice to transform into liquid water.
Directionality of Hydrogen Bonds: Maximizes electrostatic interaction. H-bonds involve a hydrogen atom covalently bonded to an electronegative atom (the donor) and another electronegative atom (the acceptor, usually oxygen or nitrogen). Strong hydrogen bonds are linear, while