Study Notes on Water and Life

Overview of Water

  • Water (H₂O) is essential for life and is a polar molecule with a partial negative charge on oxygen and positive charges on hydrogen atoms.

Ice and Liquid Water

  • Ice floats because it is less dense than liquid water, insulating aquatic environments.

Hydrogen Bonding

  • Weak hydrogen bonds form between water molecules, allowing unique properties such as cohesion and adhesion.

Emergent Properties of Water:

  1. Cohesive Behavior: High surface tension due to hydrogen bonding.

  2. Temperature Moderation: Water stabilizes temperature by absorbing/releasing heat.

  3. Expansion Upon Freezing: Water expands when frozen, allowing ice to float.

  4. Versatility as a Solvent: Water dissolves many substances due to its polarity.

Temperature Regulation by Water

  • Water has a high specific heat (1 cal/(g·ºC)), preventing drastic temperature changes and moderating climates.

Evaporation

  • Evaporation cools surfaces, helping organisms regulate temperature.

Water as a Solvent

  • Aqueous solutions are homogeneous mixtures where water dissolves solutes creating hydration shells.

Acid-Base Chemistry

  • Water can dissociate into H⁺ and OH⁻, with a neutral pH of 7 and pH changes impacting biological processes.

Buffers

  • Buffers minimize pH changes in solutions, maintaining stability in biological systems.

Ocean Acidification

  • CO₂ absorption leads to lower ocean pH, affecting marine life and ecosystems.