Seawater Chemistry

Without water, there would be no:

Water RULES!

So, how does this SIMPLE molecule, composed merely of two hydrogen atoms and one oxygen atom (H2O), do ALL of the amazing things that it does?

Here are ten properties of water that are familiar to us

all:

Properties of (Sea)WaterProperties of (Sea)Water

Universal Solvent

Polarity

The Dissolving Power of Water

Cohesion & Adhesion

Surface Tension

Salinity

Salt flat in Bolivia• Utah's Salt Flat Video

Major ions in seawater

Ion Concentration (ppt)

Percentage %

19.3 55

10.7 30.6

2.7 7.7

1.3 4

0.4 1.18

0.4 1.11

Principle of constant proportions

• For example:

• In any sample of seawater, whether it has a salinity of 20 ppt or 40 ppt:

• chlorine accounts for 55% of the ions, sodium comprises 30.6%,

• sulfate makes up 7.7% ....

Factors affecting salinity

• Evaporation or freezing

• Frequent precipitation or melting ice

Tools for Measuring salinity

Sources of salts

Density

Salt wedge

Osmoregulation

Osmoregulators vs. Osmoconformers

Osmoregulators: are able to adjust their internal fluid/solute concentrations so that they remain relatively constant. (The methods used are called osmoregulatory mechanisms. Some methods include:

examples

Osmoconformers are organisms that "conform" to their surrounding solutions. They have no methods to adjust their internal fluid/solute concentrations. As outside changes, they change with it or die. Examples:

Heat Vs. Temperature

100º Celsius (200ºF) 100º Celsius

Which container has molecules with the higher average kinetic energy?

Which container has the most heat energy?

Water has a high heat capacity!

Water can absorb a tremendous amount of

heat!

Heat capacity graph for water

You experience this here!!!

Temperature - Very important!

Fresh water freezes at 32 degrees Fahrenheit but seawater freezes at about 28.4 degrees Fahrenheit, because of the salt in it.  Ions dissociate.

• Molecular Animation

Icefish LabFreezing Point Depression Lab

• Quiz tomorrow!!!