Properties of Water

Properties of Water

Fundamental Aspects

• Water (H₂O) consists of two hydrogen atoms and one oxygen atom.

• Molecular weight of water: 18 g mol⁻¹.

Unique Characteristics of Water

• Water exists naturally in all three physical states (solid, liquid, gas).

• High surface tension among common liquids, leading to unique drop and bubble formation.

• Thermodynamic properties:
    - Expands upon freezing (ice floats).
    - High latent heat, heat of evaporation, and heat capacity.

• Water is the best solvent, capable of dissolving numerous substances.

• High transparency in visible light, important for photosynthesis.

Molecular Structure

• Water molecules are polar; oxygen has a negative charge, hydrogen has a positive charge.

• Polar nature allows for hydrogen bonding and cohesion, contributing to high surface tension.

Surface Tension and Cohesion

• Cohesion results in rounded water drops.

• Adhesion with other substances explains the wetness of water.

Temperature and Density Relations

• Water density increases as it cools, except when it starts to freeze (ice is less dense).

Heat Capacity and Climate Impact

• Water has a high heat capacity, moderating temperature changes in surroundings.

• Significant effect on global climate beyond just phase changes.

Solar Radiation and Transparency

• Solar energy transmission through water varies with wavelength, affecting photosynthesis.

• Only a thin layer of water is illuminated by sunlight; deeper depths absorb significant wavelengths.