The Physical and Chemical Properties of Water

The Water Molecule

• H₂O - dipole structure

• Hydrogen Bonds

• Solvent power & high heat capacity

Changes of State

• Temperature and Heat

– Average kinetic energy versus total kinetic energy

• The physical states of water

– Liquid, solid, and gas

– H bonds = high heat capacity

– Latent heat of fusion

– Latent heat of vaporization

Other consequences of H bonds

• Cohesion

• Surface Tension

• Viscosity

H₂O Density

• 1 g/cm³

• Temperature and density

• How does salinity influence density?

Transmission of Energy

• Heat - Conduction, convection, radiation

• Light

• Visible light

• Refracted, absorbed, scattered

• Attenuation

• How far does light penetrate into the ocean

• Photic Zone

The Chemistry of Seawater

^• Acidity and alkalinity - H⁺ and OH^-

• pH

• pH of Seawater = 7.8

^• Why is seawater buffered?

Salinity

• Solvent power

• Disolved ions

Salinity

amount of dissolved ions in seawater..

-> normal salinity = 3.5% or 35‰ parts per thousand (ppt)

Tropics = lowest salinity->high precip.=> 34.5‰

Subtropics=highest salinity ->high evaporation => 36‰

Why does this surface pattern exist?

Salinity

• Where does the salt come from?

• Why is salinity so stable?

Chemistry of Seawater

• Major constituents

• Trace elements

• Conservative

• Principle of Constant Proportion

Chemistry of Seawater

• Gasses

_– N₂, O₂, and CO₂

• Why are concentration of O₂ high but CO₂ low in the upper 100 m?

• Why does O₂ reach a minimum between 200 and 800 m?

• Temperature, salinity, and pressure

CO₂ and O₂

• The Carbon Cycle

• The biological pump - deep ocean = carbon sink

• The Oxygen Balance

– Photosynthesis <=> Weathering

Nutrients

• N, P, and Si

• Nonconservative elements

• Limiting elements