1. Chemical Properties of Seawater

2. I. The water molecule 1.Made of two hydrogen atoms and one oxygen atom

3. 2.It is a polar molecule (molecule with positive and negatively charged ends) 3.The positive hydrogens are attracted to the negatively charged oxygen end of nearby water molecules

4. 4.This attraction creates a bond between water molecules called a hydrogen bond. 5.Hydrogen bonds give water many of its unique properties.

5. II. The effects of hydrogen bonds 1.Liquid water at room temperature 2.Cohesion (sticks together)/adhesion (sticks to other things) 3.Viscosity- the tendency of a fluid to resist flow 4.Surface tension- the water’s resistance to objects attempting to penetrate its surface http://www.youtube.com/watch?v=2F64qh9qPAI http://www.youtube.com/watch?v=u5AxlJSiEEs http://www.youtube.com/watch?v=2F64qh9qPAIhttp://www.youtube.com/watch?v=u5AxlJSiEEs

6. 5.Ice floats a.Water becomes more dense at it cools b.However, when water turns to ice hydrogen bonds spread the molecules into a crystal structure that takes up more space than liquid water c.Therefore, ice is less dense than water

7. Water Liquid vs Ice

8. http://www.youtube.com/watch?v=oAY3yISf- 24 http://www.youtube.com/watch?v=oAY3yISf- 24

9. III. Solutions and Mixtures 1.Solution- when the molecules of one substance are evenly dispersed among the molecules of another substance a.Solvent- the more abundant substance in a solution, usually a liquid b.Solute- the less abundant substance that is being dissolved, usually a solid or gas c.Water is the universal solvent. 2.Mixture- when two or more substances are closely mixing but retain their individual characteristics

10. IV. Salinity 1.Salinity- the total amount (concentration) of dissolved inorganic solids in water 2.Major salts in water: sodium chloride (NaCl) and potassium chloride (KCl) 3.Measured in parts per thousand (‰- the grams of inorganic solids left behind when 1000 grams of water is evaporated) 4.35‰ is the average salinity of the oceans

12. V. Colligative Properties of Seawater Properties of a liquid that may be altered by the presence of a solute 1.Raised boiling point 2.Decreased freezing temperature 3.Ability to create osmotic pressure

13. Osmotic Pressure a.Osmosis- diffusion through a semipermeable membrane such as a cell wall b.Osmotic pressure- the pressure difference caused when a substance exists in a differing concentrations on two sides of a semipermeable membrane

14. 4.Electrically conductive 5.Decreased heat capacity- it takes less heat raise the temperature of salt water than is does to raise the temperature of fresh water 6.Slowed evaporation

15. VI. The Principle of Constant Proportions - The constant relationship of proportions of inorganic dissolved solids in seawater

16. VII. Dissolved Solids in Seawater 1.The major ions in water and their ~ concentration in 1000 g of 35‰ water Chloride 18.98 g Sodium 10.56 g Sulfate 2.65 g Magnesium 1.28 g Bicarbonate 0.14 g Calcium 0.40 g Potassium 0.38 g Other 0.61 g

17. VIII. Determining Salinity 1.Can be measured with a conductivity meter, CTD, or refractometer 2.If the amount of one of the major ions in seawater is known, the salinity can be determined using proportions.

18. IX. Why the Seas are Salty 1.The ocean’s salinity is relatively stable. 2.Sources a.Weathering of mountains b.Volcanic precipitation 3.Removal a.Biological processes b.Adsorption to sediment c.Sea spray d.Removal at hydrothermal vents

19. XI. Acidity and Alkalinity 1.pH- a scale that represents the balance between the positive hydrogen ions (H + ) and negative hydroxide ions (OH - ) 2.More H + - acidic 3.More OH - - alkaline or basic 4.pH scale ranges from 0-14 5.A pH of 7 is neutral 6.Below 7 acidic 7.Above 7 alkaline

20. X. Acidity and Alkalinity 8.Pure water has pH of 7 9.Seawater ranges from 7.8-8.3 10.Seawater’s pH is relatively stable because of buffering by carbon dioxide – Buffer- a substance that reduces the tendency of a solution to become too acidic or too alkaline

21. X. Acidity and Alkalinity 11.pH in the ocean’s varies with depth because the carbon dioxide tends to vary with depth

22. XI. Dissolved Gases Dissolved gases are part of the solution of seawater Dissolved gases include: – Oxygen – Carbon dioxide – Nitrogen

23. I. The water cycle – the cycle that controls the distribution of water on Earth

24. Create your own water cycle Use the words – Condensation- the conversion of water from vapor to liquid form – Evaporation- the conversion of water from liquid to gas form without adding energy – Precipitation- water (rain, snow, hail, etc) that falls to the Earth’s surface out of the atmosphere – Transpiration- the release of water vapor from plants leaves – Runoff- rainfall that is not absorbed by the ground