Chapter 3: Chemical and Physical Features of Water

polar molecule

polar molecule

a molecule (such as water) with an uneven distribution of charge

what end of a water molecule has a partial negative charge?

oxygen

what end of a water molecule has a partial positive charge?

hydrogen

hydrogen bonds

the reason water molecules "stick" together.

cohesion

the attraction of molecules for other molecules of the same kind

surface tension

results from greater attraction of water molecules to each other (due to cohesion) than to molecules in the air (due to adhesion)

how does ice affect aquatic organisms?

Because ice is less dense than water, it acts as an insulating blanket that helps keep the water below from rapidly cooling off

why is high heat capacity good for marine organisms?

This is good for marine organisms because they are not subjected to rapid or drastic changes in temperature

how are solids dissolved in seawater?

chemical weathering of rocks on land

salinity

is defined as the total amount of salt dissolved in seawater

what is the average salinity of the ocean?

Average salinity of the ocean is 35 ppt (parts per thousand) or
3.5%

most abundant ions in seawater

chlorine followed by sodium

rule of constant proportions

the relative amounts of each of the various ions in seawater is always constant

evaporation

the process that changes liquid water to gaseous water (water vapor)

freezing

the process that causes a substance to change from a liquid to a solid

precipitation

water released from clouds in the form of rain

• Also added by the melting of glaciers and ice

highest salinities

Latitudes where evaporation is greater than precipitation

lowest salinities

latitudes that get greater rainfall

how does salinity affect freezing temperature?

it increases

what type of water does gas dissolve better in?

cold water

transparency of water

Ability of light to penetrate the ocean

what color penetrates seawater the farthest?

blue

what color penetrates seawater the shortest?

red

transparency

Different colors of light penetrate to different depths in the ocean

pressure

• changes dramatically with depth in the ocean

• On land (sea level), we are under 1 atmosphere of pressure (or 14.7 pounds/square inch, psi)

ATM

every ten meters is another atmosphere (ATM) of pressure

effect of pressure on organisms

• As pressure increases, gases are compressed

• Gas filled organs (air bladders and lungs) shrink

• Our lungs would collapse under the pressure