1. The Physical and Chemical Properties of the Ocean

2. Physical Properties of Water
Light
Sunlight is absorbed as it enters the ocean.
All colors of light are given off by the sun.
Red is the 1st color to be absorbed
Blue light is the last color absorbed and penetrates the furthest.

3. Physical Properties of Water
Why are many small prey organisms red?
A red organism appears red because it reflects red light.
Red light does not penetrate more than 10 meters.
Since there is no red light to reflect, a red organism would appear black below 10 meters.

4. Physical Properties of Water
Temperature
As you dive deeper in the ocean the temperature decreases.
Thermocline: the layer of water that shows a large amount of temperature change with depth.
Above the thermocline: The surface water is heated by the sun.
Below the thermocline: There deep water is uniformly cold.

5. Physical Properties of Water
Pressure
As you dive deeper in the ocean the pressure increases.
For every 10 meters you dive into the ocean the pressure increases by 14.7 psi. (1 ATM)
Diving deeper into the ocean Increases pressure and causes the gases in the organism’s body to compress.
Rising to the ocean surface decreases pressure and causes the gases in the organism’s body to expand.

6. Physical Properties of Water
Sound
Sound travels further in water than it does on land but our ears are not designed to hear underwater.
Slower moving (low-pitched) sounds travel further.
Decreasing temperature, decreases sound speed, increases distance
Increasing pressure, increases sound speed, decreases distance
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7. Physical Properties of Water
Sound
SOFAR Channel: The depth of the ocean where sound travels the slowest and the furthest.
Above the SOFAR channel: Sound doesn’t travel as far because temperature is too high.
Below the SOFAR channel: Sound doesn’t travel as far because pressure is too high.
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8. Chemical Properties of Water
Molecular Formula: H2O
Molecular Structure: every molecule of water contains 1 oxygen atom and 2 hydrogen atoms.
Each hydrogen atom is bonded to the oxygen atoms with a covalent bond.
What is a covalent bond?

9. Chemical Properties of Water
Water is a polar molecule.
Polar Molecule: a molecule that has a slightly positive side and a slightly negative end.
There are more electrons surrounding the oxygen atom than the hydrogen atoms.
Oxygen atom has a slightly negative charge.
Hydrogen atoms has a slightly positive charge.

10. Chemical Properties of Water
Hydrogen Bonds: A weak bond that forms between the positive end of one water molecule and the negative end of another water molecule.
How is a hydrogen bond different than a covalent bond?
Properties of Water
Adhesion: a water molecule forms a hydrogen bond to a surface or an object.

11. Chemical Properties of Water
Cohesion: a water molecule forms a hydrogen bond with another water molecule.
Cohesion makes water have high surface tension – it is difficult to break the surface of a body of water.
Cohesion makes water a viscous liquid – it is difficult to move through.

12. Chemical Properties of Water
Water molecules and in constant motion. The higher the temperature the faster the molecules are moving.
The Three States of Water:
Gas (vapor): When a water molecule moves fast enough it breaks free of all hydrogen bonds and becomes a gas.
Water molecules are spread much further apart than in liquid water.
Increasing temperature, increases the rate of evaporation.

13. Chemical Properties of Water
The Three States of Water:
Liquid: Hydrogen bonds hold most of the water molecules together in small groups.
Hydrogen bonds are constantly being broken and reformed.
Cold Water: Is more dense because molecules move slower and packed in tighter causing.
Warm Water: Is less dense because molecules move faster and spread out.

14. Chemical Properties of Water
The Three States of Water:
Ice: when water freezes, the molecules move so slowly that hydrogen bonding locks each molecule in place forming a crystal.
In ice, the water molecules are further apart than in liquid water.
Ice is less dense than liquid water.
Why is it important that ice floats in the ocean?

15. Chemical Properties of Water
Heat Capacity: The amount of energy needed to raise the temperature of a substance.
Water has the highest heat capacity of any natural substance.
Heat energy must be used to break hydrogen bonds between water molecules before the molecules are able to move faster and increase temperature.

16. Chemical Properties of Water
It takes a long time and a lot of energy for water to heat up or cool down.
Water’s high heat capacity protects marine organisms from drastic changes in temperature that you may experience on land.
A relatively constant ocean temperature helps marine organisms maintain homeostasis: an organism’s ability to maintain constant and stable internal conditions.

17. The pH of Ocean Water Acid, Bases and pH
Water molecules sometimes split apart to from ions.
Pure water is neutral it has a equal number of positive and negative ions

18. The pH of Ocean Water Acids
Have more H+ ions than OH- ions in solution.
pH less than 7
The lower the number, the stronger the acid.
Ex: HCl is a strong acid produced by the stomach to digest food.
Bases
Produces more OH- ions than H+ in solution
pH greater than 7
The higher the number the stronger the base.
Ex: Ocean water has a pH of 8

19. The pH of Ocean Water pH: (power of Hydrogen) as in Hydrogen ions
Measures the H+ concentration in solution: [H+]
It is a log scale, so it increases by powers of ten.
Ex: How many times more acid is vinegar compared to coffee?

20. The pH of Ocean Water
Buffer: A solution that prevents sharp and sudden changes in pH.
Ocean water acts as a buffer and resists changes in pH.
Many land animals have buffers in their blood that maintain a constant pH.
If the pH of an organism changes, it will affect the chemical reactions inside their cells.
Buffers help organisms maintain homeostasis with respect to pH.

21. Chemical Properties of Saltwater
Salt: any substance that consists of negatively charged particles bonded to positively charged particles.
Table Salt (NaCl) is only one example of a salt
The Na atom loses an electron, forming an ion with a positive charge.
The Cl atom gains an electron, forming an ion with a negative charge.

22. Chemical Properties of Saltwater
Salt crystals dissolve in water
The negative end of the water molecules are attracted to the positive ions in salt.
The positive end of the water molecules are attracted to the negative ions in salt.
Water molecules surround each ion and keep them separated.

23. Chemical Properties of Saltwater
Salinity: the amount of salt dissolved in water
The average salinity of the ocean is 35 ppt (parts per thousand).
How many grams of salt are there in 2,000 grams of saltwater?

24. Chemical Properties of Saltwater
Why is there so much salt in ocean water?
Negative ions come from volcanic eruptions and deep sea hydrothermal vents
Positive ions fcome rom weathering rock are carried to the ocean through streams and rivers

25. Chemical Properties of Saltwater
Rule of Constant Composition: the percentage of each chemical dissolved in ocean water will always remain the same.
The salinity (35 ppt) changes with depth.
The “stuff” dissolved in the water will always be the same.
If you sample water from any ocean at any depth the % of each chemical dissolved will be the same.