1. DISSOLVED SALTS IN THE OCEAN
4/14/17
DISSOLVED SALTS IN THE OCEAN
Objective: I will explain how salt dissolves in water.
PAGE 77

2. Dissolved Salts Sea salts form from 3 sources: Volcanic eruptions
Chemical weathering of land rocks
Chemical reactions between water and sea rocks

3. Structure of Salt (NaCl)

4. Structure of Salt (NaCl)
salt (NaCl) is made up of a positive sodium ion and a negative chloride ion
ion: atom with different # of electrons, giving it a charge
More electrons- negative charge
Less electrons- positive charge
When many Na+ and Cl- attract each other, they form a salt crystal in the shape of a cube

5. Structure of Salt (NaCl)

6. The Water Molecule (H2O)

7. The Water Molecule (H2O)
Two hydrogen atoms bonded to one oxygen atom
Oxygen attracts the hydrogen’s electron, moving it to one side of the atom
Therefore:
oxygen side of the molecule has a – charge
hydrogen side of the molecule has a + charge
Known as a polar molecule

8. The Water Molecule (H2O)

9. The Water Molecule (H2O)

10. Dissolved Salts in Water

11. Dissolved Salts in Water
When salt is put in water:
Positive end of H2O attracts Cl-
Negative end of H2O attracts Na+
This attraction pulls the salt cube apart

12. Dissolved Salts in Water

13. Dissolved Salts in Water

14. Dissolved Salts in Water
NO CHEMICAL CHANGE TAKES PLACE!
Only physical change
If we evaporate the H2O, the salt will recombine
This is why salt is left behind after evaporation

15. Dissolved Salts in Water
Salinity is a measure of the amount of dissolved salts in water
Salinity is not homogenous (uniform) across the Earth’s oceans
Both salinity and temperature affect the density of seawater
ON average salt water is 96.5% pure water and 3.5% compounds including dissolved salts

16. Dissolved Salts in Water

17. Dissolved Salts in Water
Three primary factors influence salinity:
1.  Freshwater input - High rates of freshwater input (river inflow to the sea; melting ice) will decrease salinity
2.  Evaporation - High rates of evaporation will increase salinity
3.  Precipitation - High levels of rainfall will decrease salinity

18. Dissolved Salts in Water
Three primary factors influence salinity:
1.  Freshwater input - High rates of freshwater input (river inflow to the sea; melting ice) will decrease salinity
2.  Evaporation - High rates of evaporation will increase salinity
3.  Precipitation - High levels of rainfall will decrease salinity

19. Dissolved Salts in Water
Lake Retba, the Pink lake of Senegal.
Pink color is caused by Dunaliella salina algae.
Salinity is 40% in some areas.

20. Dissolved Salts in Water
Baltic Sea
Salinity is 1% in some areas

21. Dissolved Salts in Water
What happens when water at different depths has different densities?
Layers of water will form
Formation of layers is part of the reason we have ocean currents

22. Output Activity (page 76)
Draw Figure 5. of ocean layers on page 498 in the YELLOW Earth Science book.
Add color!
Make sure the diagram is big and detailed.
Draw one fish...