1. Lesson 3.2: Salinity
*Refer to Chapter 8 in your Textbook

2. Learning Goals:
I can differentiate between compounds, mixtures, and solutions.
I can explain why the ocean is salty.
I can explain how marine organisms osmoregulate.

3. Compounds
Compound: a substance formed by the chemical combination of two or more elements using ionic bonds
Na (Sodium) Cl (Chlorine)  NaCl (Salt)

4. Mixtures
Mixture: two or more elements or compounds that are physically combined but not chemically combined
Suspensions: material that does not dissolve in a mixture

5. Solutions
Solution: two or more elements or compounds that are mixed completely
Solute: substance being dissolved (ex. salt)
Solvent: dissolver (ex. water)
Solute + Solvent = Solution

6. Solubility Solubility: A solutes ability to be dissolved in a solvent
As temperature increases, solubility increases
(Ex. Sugar dissolves better in hot coffee over iced)

7. Salinity The ocean is a solution of water and dissolved materials
Salinity is the measure of dissolved solids in the water
Average salinity of the ocean = 35 ppt
PPT = “parts per thousand”
grams of salt per liter water

8. Types of Dissolved Solids
Majority is table salt: Sodium Chloride (NaCl)
Dissolved Solids in the Ocean:
Chloride (Cl) grams
Sodium (Na) grams
Sulfate (SO4) grams
Magnesium (Mg) 1.28 grams
Other grams
Calcium (Ca) 0.4 grams
Potassium (K) grams
Bicarbonate (HCO3) 0.14 grams

9. Where does the Salt Come From?
Water is an excellent solvent, which implies that wherever there is water, it is carrying materials with it
1) From land:
Particles transported via
freshwater streams and rivers
2) From the atmosphere:
Particles transported via wind
3) From inside the Earth:
Minerals are spewed out of volcanoes
and hydrothermal vents

10. How does Salinity & Temperature Affect Density?
Salinity & Density:
The greater the salinity, the greater the density
The greater the density, the better you float
Temperature & Density:
The lower the temperature, the greater the density
Cold, salty water sinks!

11. Salinity and Marine Organisms
Osmosis
The movement of solvent through a semipermeable membrane to an area of higher solute concentration
Moves High-to-Low

12. Salinity and Marine Organisms
Hypertonic: water out, causes shriveling
Isotonic: neutral
Hypotonic: water in, causes swelling

13. Salinity and Marine Organisms
Freshwater Fish:
Put in saltwater would be a hypertonic solution, causing the fish to shrivel & dehydrate
Saltwater Fish:
Put in freshwater would be a hypotonic solution, causing the fish to swell and burst from water pressure

14. Salinity and Marine Organisms
Osmoregulation: balancing the amount of water and salt in your body to remain isotonic
Freshwater Fish:
Gain water through osmosis & food
Absorb salt through gills & food
Dilute watery urine
Saltwater Fish:
Gain water and salt through eating and drinking
Lose water and salt through osmosis
Salty urine

15. Osmoregulation