1. Seawater Chemistry

2. Pure substances that cannot be broken down into simpler chemical entities by ordinary chemical reactions. Elements Periodic Table 112 known elements

4. Major Elements Comprising the Biological Molecules of Living Things C arbonC arbon H ydrogenH ydrogen O xygenO xygen N itrogenN itrogen P hosphorusP hosphorus S ulfurS ulfur

5. Other Major Elements of Living Things Calcium (Ca)Calcium (Ca) Potassium (K)Potassium (K) Chlorine (Cl)Chlorine (Cl) Magnesium (Mg)Magnesium (Mg)

6. Atomic structure Atoms are the building blocks of all matter Nucleus contains: –Neutrons (no charge) – Protons (+ charge) Outer shell(s) contain: –Electrons (– charge)

7. proton neutron electron hydrogen atom helium atom carbon atom Electron Shell Configurations of Atoms 1p, 0n, 1e-2p, 2n, 2e- 6p, 6n, 6e-

8. atomic number: number of p; #p = #e- 2 He  2e- and 2p He

9. atomic mass (atomic wt.) : sum of masses of p+n He  2p + 2n, atomic mass = 4 4 2 He He p + ne-

10. p = n = e- = Atomic number = Atomic mass = C Carbon Atom

11. O16O17O18 stable isotopes Isotope Atoms that differ in the number of neutrons 16 8 O 18 8 O 17 8 O #p #p+n O

12. Molecule Two or more atoms held together by chemical bonds OxygenO 2 NitrogenN 2 AmmoniaNH 3 Carbon DioxideCO 2 WaterH 2 O MethaneCH 4 GlucoseC 6 H 12 O 6

13. Ion An atom that has either gained or lost electrons such that it exhibits a net charge Na + Cl -

14. Sodium (Na) Atom 11 P + 12 N o

15. Sodium (Na + ) Ion 11 P + 12 N o

16. Chlorine (Cl) Atom 17 P + 18 N o

17. Chloride (Cl - ) Ion 17 P + 18 N o

18. Some Examples of Ions HydrogenH + PotassiumK + Fluoride F - Calcium Ca +2 NitrateNO 3 -NitrateNO 3 - PhosphatePO 4 -3PhosphatePO 4 -3

19. Bond Types Bond Types : Ionic Covalent Hydrogen

20. Ionic Bonds Transfer of electron 17 P + 18 N o 11 P + 12 N o

21. Covalent Bonding: Covalent Bonding: electron sharing O H H

22. Between Water Molecules Covalent bond Hydrogen bond

23. Boiling Point: 100 o C Freezing Point: 0 o C Density: 1g/cm 3 Properties of Water gasliquid solid

24. The formation of ice As water cools to 4°C: –Molecules slow –Water contracts –Density increases Below 4°C: –Hydrogen bonds form –Water expands As water freezes: –Expands by 9%

25. IceDensity vs Temp ( o C)

26. Properties of Water 1.High heat capacity 2.High heat of vaporization 3.High Surface tension 4.Polarity solvent properties

27. Properties of Seawater Heat capacity: Heat capacity with salinity Evaporation: Evaporates more slowly than fw Specific gravity: Pure water density = 1.000 g/cm 3 Seawater (2 o C) density = 1.028 g/cm 3 Seawater’s Boiling Point: As salinity, the boiling point

28. Seawater’s Freezing Point: As salinity, the freezing point Salt is an antifreeze- doesn’t freeze until -2 o C ( @ 35 o / oo ) Pancake ice

29. Refractometer Salinometer

30. Na + - Weathering of crustal rock Cl - - from the mantle by way of volcanic vents and outgassing from mid-ocean rifts Mg ++ - mid ocean rifts

31. Processes affecting seawater salinity Processes that decrease seawater salinity: –Precipitation –Runoff –Icebergs melting –Sea ice melting Processes that increase seawater salinity: –Sea ice forming –Evaporation

32. Salt IonIons in sw ( 0 / 00 ) Cl - 18.980 Na + 10.556 SO 4 2- 2.649 Mg 2+ 1.272 Ca 2+ 0.400 K + 0.380 HCO 3- 0.140 Br - 0.065 H 3 BO 3 0.026 Sr 2+ 0.013 F - 0.001 Total34.38

33. Global surface salinity

34. Salinity variations Location/typeSalinity Normal open ocean33-38‰ Baltic Sea10‰ (brackish) Red Sea42‰ (hypersaline) Great Salt Lake280‰ Dead Sea330‰ Tap water0.8‰ or less Premium bottled water0.3‰

35. Global ocean circulation that is driven by differences in the density of the sea water which is controlled by temperature and salinity.

36. White sections represent warm surface currents. Purple sections represent deep cold currents

37. Desalination The production of drinkable water from seawater Techniques: 1.Distillation- water vapor and condensation 2.Freezing- ice crystals form leaving salt behind 3.Reverse osmosis- sw is forced through a semipermeable membrane; only water molecules pass through 4.Electrodialysis- e- charged, semipermeable membranes draw salt ions out of sw 5.Salt absorption- chemically active resins or charcoals are used to draw off the dissolved salt ions  fw

38. Distillation of seawater seawater evaporation freshwater Solar energy Widely used technique plastic

39. Reverse Osmosis

40. Acids HCL  H + + Cl - Proton donor, i.e., they donate H + ions HCl is a strong acid with a pH 1-2

41. Na + + OH -  NaOH NH 3 + H +  NH 4 OH - + H +  H 2 O HCO 3 - +H +  H 2 CO 3 Proton acceptor, i.e., they take up H+ ions NaOH is a strong base ~pH 12 Bases

42. Neutralization- HCl + NaOH  H 2 O + NaCl

43. Buffer- resists dramatic changes in pH; ex. tums, rolaids…buffers stomach acid

44. Acidic0-6 Neutral7 Basic (alkaline)8-14 Type of Solution pH Value 0-14

45. Logarithmic scale blood

46. Carbon Dioxide System in the Ocean Respiration Photosynthesis C 6 H 12 O 6 +6O 2 6CO 2 + 6H 2 O 6CO 2 + 6H 2 O C 6 H 12 O 6 +6O 2 Air Water CO 2 gas

47. CO 2 + H 2 O ↔ H 2 CO 3 ↔ HCO 3 - + H + ↔ CO 3 2- + 2H + By-product of respiration carbonic acid bicarbonate carbonate The addition of CO 2 makes water acidic The effects of CO 2 in an ocean system

48. Bicarbonate buffer Seawater too basic: H 2 CO 3 HCO 3 - + H + pH drops Seawater too acidic: HCO 3 - + H + H 2 CO 3 pH rises

49. Ocean Acidity

50. Global Ocean Acidity

51. Consequences of Ocean Acidity Animals with CaCO 3 skeletons affected Plankton Corals Mollusks Fish http://news.bbc.c o.uk/2/hi/science /nature/7933589.stm Fisheries

52. In a high CO 2 world, the ocean will be… More acidic More stratified More oligotrophic, but better light conditions Less oxygenated Consequences of Ocean Acidity

53. Acid Rain in Marine Environment reduces ability of marine organisms to utilize calcium carbonate Coral calcification rate reduced 15-20% Skeletal density decreased, branches thinner

54. Inquiry 1.How many neutrons in 7 N? 2.Why do all the oceans have relatively the same proportion of salinity? 3.At what temperature is fw most dense? 4.Of the following pH’s which is most acidic? 3762 5. Why are there no plants at the compensation depth? 6. Why can a water strider walk on water? 7. Besides temperature and salinity, what physical factor effects thermohaline circulation? 8. What is the oceans most dense sea water called? 14