2.1 Seawater Properties
The Remarkable Properties of Water
Water is a unique molecule with properties that make it essential for life and ocean dynamics. Its molecular structure (H₂O) with polar bonds creates hydrogen bonding, giving water exceptional thermal and physical characteristics.
Unique Properties of Water
High Heat Capacity
4.18 kJ/(kg·K) - Moderates Earth's climate by absorbing/releasing large amounts of heat with small temperature changes.
High Latent Heat
Evaporation: 2.26 MJ/kg. Drives global heat transport from tropics to poles.
Maximum Density at 4°C
Fresh water is densest at 4°C (not at freezing). Ice floats, insulating water below.
Universal Solvent
Dissolves more substances than any other liquid. Seawater contains ~3.5% dissolved salts.
Seawater Composition
Major ions in seawater (by mass at S=35):
These 6 ions account for 99.3% of dissolved salts. Ratios are nearly constant globally (Principle of Constant Proportions).
Thermal Properties
4.18
kJ/(kg·K)
Specific Heat
-1.9°C
at S=35
Freezing Point
2.26
MJ/kg
Latent Heat (evap)