General Oceanography: Seawater Properties

Water has ____ in covalent bonds between O and H

shared electrons

In solids, the atoms of water:

• vibrate weakly

• rigidly held together

• forms hexagonal structures and molecules spread out

• results in low density

In liquids, atoms:

• vibrate more rapidly

• farther apart

• free to move relative to each other

Potential temperature and what it tells us

water temp minus the temp increase produced by the compression of water. Temp of what the water should be when brought up to ocean surface.

• Helps calculate true density anomalies

• analyze vertical instability in deep ocean layers

In gases, atoms:

• highly energic

• move apart

• largely independent of one another

___controls density. As temp ___, atoms _____, density ______.

temp, increases, decreases

___allows hydrogen bonds to form between water molecules resulting in unique properties.

Polarity

Unique properties of water

• higher melting and boiling point than other hydrogen molecules

• only substance present in all 3 phases at natural temp and pressure of Earth

• solid phase less dense than liquid

• density changes with temp

• exceptional solvent

• high surface tension

maximum amount of clustering in liquid water occurs at ____, so that is the temp of maximum ___. Thermal expansion ____ density at temperature >3.98 deg C. This leads to _____ in lakes.

3.98 deg C, density, decreases, seasonal overturn

Calorie

the amount of thermal energy to raise the temp of 1g of water by 1 deg C at pressure of 1 atm.

Heat capacity

heat required to raise tempo of 1g of substance by 1 deg C.

High latent heat of vaporization and latent heat of melting

energy absorbed or released during phase change

High surface tension and implications of it

molecules at surface form stronger bonds

• capillary waves

• retain gas bubbles in water

• retain water droplets in air

• transport through xylem

polar structure of water make it an exceptional ___. Na and Cl ions are ___ from halite crystal by negative and positive ends of water molecules

solvent, removed

major salt ions in sea water

• sodium

• chloride

• sulfate

• magnesium

• calcium

• potassium

salinity effects water properties by

• increasing density

• decreasing freezing point

• decrease temp of max density: pull water molecules and break up low density clusters

• decrease heat capacity: dissolved ions disrupt waters hydrogen networks, leaving fewer free molecules to store thermal energy

• decrease evaporation rate: salt reduces escaping tendency, by forming tight bonds around charged salt ions, requiring more energy to break apart

• increase boiling point: Na and Cl ions create extra electrostatic attractions with water, requiring more heat for water to escape.