Unique properties of water overview

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Hydrogen bonds, crystal lattice, specific heat, etc.

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Unique properties of water overview

  1. 1. The Water Planet<br />
  2. 2. <ul><li> 97% of all water on our planet is in the oceans.
  3. 3. Fresh water represents the remaining 3% (2/3 is snow and ice in glaciers / polar ice caps).
  4. 4. Liquid and solid water cover roughly 3/4 of Earth's surface area.
  5. 5. 29% of the earth’s surface is above sea level (71% is below )</li></li></ul><li>Unique properties of water<br />Absorbs or releases more heat than most other substances for every temperature degree of change<br />Water is a good solvent and can dissolve more substances than other fluids, even rocks<br />Water exists in 3 physical states that can power thunderstorms/hurricanes and help transport the sun's energy, nutrients, and organisms<br />
  6. 6. More than half the world's population live within 60km of a coastline <br />South Florida, USA<br />
  7. 7. Overview<br />Chemical properties of water<br />H bonds<br />Ice<br />Salinity and Sources<br />Physical properties of water<br />Biomechanics<br />Density<br />Temperature<br />
  8. 8. Chemical properties of water<br />Hydrogen Bonds<br />Crystalline Structure<br />Surface Tension<br />Tensile Strength<br /> Specific Heat <br /> Evaporation<br /> Molecular Interactions<br /> Movement and Transport <br />
  9. 9. Chemical properties of water<br />Hydrogen Bonds<br />Crystalline Structure<br />Surface Tension<br />Tensile Strength<br /> Specific Heat <br /> Evaporation<br /> Molecular Interactions<br /> Movement and Transport <br />
  10. 10. Hydrogen Bonds<br />d-<br />O<br />H<br />H<br />d+<br />d+<br />
  11. 11. Hydrogen Bonds<br />
  12. 12. Hydrogen Bonds<br />3 physical states of water:<br />WATER VAPOR<br />
  13. 13. Crystalline Structure<br />
  14. 14. Crystalline Structure<br />
  15. 15. Ice<br />
  16. 16. d-<br />O<br />H<br />H<br />d+<br />d+<br />Surface tension<br />Water has high surface tension due to lateral and downward attraction between individual molecules, which stretches the water's surface, creating a thin skin<br />
  17. 17. Surface tension<br />Water has high surface tension due to lateral and downward attraction between individual molecules, which stretches the water's surface, creating a thin skin<br />
  18. 18. Surface tension<br /><ul><li> Water striders can walk upon the water's surface.
  19. 19. Members of the neuston depend upon the surface film of water for transport and food.
  20. 20. Liquid water on surfaces to which it does not adhere well "beads-up."
  21. 21. Surface tension of the water allows wind to push against it, generating waves in large water bodies.
  22. 22. [Detergents reduce the surface tension of water (by as much as 70%) and allows it to spread out on a surface.]</li></li></ul><li>Tensile strength<br />Water is strong under tension.<br />The force needed to pull pure water apart can be as much as 3 x 107 Newtons/m2<br />120 lbs = 530 Newtons<br />Limpet attachment strength = 1 x 106 Newtons/m2<br />
  23. 23. Specific heat <br />Water can absorb a great deal of energy which goes to breaking hydrogen bonds but does not lead to measurable temperature increases.<br />Because of the massive number of hydrogen bonds in water, it requires a lot of energy to see even a small change in water temperature.<br />
  24. 24. Evaporation <br /> A water molecule makes the transition from a liquid phase into a gas phase. <br />Because the escaping molecule had a higher than average energy level, it leaves the liquid cooler (lower in energy) upon evaporation. <br />
  25. 25. Hydrogen Bonds - Summary<br /><ul><li>High heat capacity (1 cal/g/°C);
  26. 26. Heat of vaporization (540 cal/g);
  27. 27. Heat of fusion (-80 cal/g);
  28. 28. Solid less dense than liquid phase;
  29. 29. High surface tension</li></li></ul><li>Molecular interactions<br />Solutes<br />Dissociation of Water Molecules<br />KD = [H+][OH-]/[H2O] = 1.8 x 10-16M<br />where KD is the dissociation constant (equilibrium constant) for the dissociation of a proton from a water molecule (the smaller the KD, the stronger the binding)<br />
  30. 30. pH of solutions<br />pH - an index of the relative concentration of H+ ions in solution<br />[H+] = [OH-] = 10-7M in pure water([H2O] = 55 M)<br />pH º -log10[H+]<br />In pure water, pH = 7<br />
  31. 31. pH of solutions<br />The pH scale ranges from 0 to 14<br />The higher the pH, the lower the [H+] (alkaline, basic solutions have a high pH)<br />The lower the pH, the higher the [H+] (acidic solutions have a lower pH)<br />
  32. 32. pH of solutions<br />Examples:<br />Gastric juice = 1.0 Seawater  8.0<br />Orange juice = 4.3 Urine = 6-8.0<br />Blood plasma = 7.4 Ammonia = 12.0<br />
  33. 33. pH and the sea<br />A difference in pH from 8 to 7.8 can significantly decrease coral growth rates<br />Increased CO2 in the atmosphere lowers pH<br />Active photosynthesis and nitrogenous waste excretion can increase local pH<br />
  34. 34. Water as a polar solvent and Salinity<br />Strong Electrolytes (substances that dissociate completely when dissolved in water - ions) <br /> Salts consist of ions:<br />      NaCl ® Na+ + Cl- salt<br />                    HCl ® H+ + Cl- strong acid<br />                      NaOH ® Na+ + OH- strong base<br />For strong electrolytes, KD»¥<br />
  35. 35. Water as a polar solvent<br />Weak Electrolytes (substances that dissociate in water only to a small extent (KD»10-3M to 10-11M)<br /> H2CO3 H+ + HCO3- KD = 1.7 x 10-4M<br />KD»10-3M to 10-11M<br />
  36. 36. CO2(g)            CO2(aq)<br />(CO2 from the atmosphere <br />dissolves into seawater)<br />CO2(aq) + H2O(l)            H2CO3(aq) <br />(Carbonic acid)<br />H2CO3           H+ + HCO3-KD = 4.2 × 10-7<br />HCO3-    H+ + CO32-KD = 4.8 × 10-11<br />CaCO3(s) + 2 H+(aq)            Ca2+(aq) + H2CO3(aq) <br />Carbon dioxide-carbonate equilibrium<br />bicarbonate<br />carbonate<br /><ul><li>High CO2= low [CO32- ]</li></ul>Ocean acidification<br />
  37. 37. Water as a polar solvent<br />Because of its small size and polar nature, water dissolves many materials, more than any other liquid<br />Oceans of water act as sink for CO2 molecules – leads to acidification<br />Seawater contains almost every known naturally occurring element<br />
  38. 38. Seawater constituents<br />Component<br />Concentration<br />Percentage of Salinity<br />chloride <br />18.98 <br />55.03 <br />sodium <br />10.56 <br />30.59 <br />sulfate <br />2.65 <br />7.68 <br />magnesium <br />1.27 <br />3.68 <br />calcium <br />0.40 <br />1.18 <br />potassium <br />0.38 <br />1.11 <br />bicarbonate <br />0.14 <br />0 <br />
  39. 39. Seawater constituents<br /><ul><li>Average ocean water has a salinity of 35.0
  40. 40. This means that 1000 g of average seawater contains 965 g of water and 35 g of salts.</li></li></ul><li>Dissolved<br />chemicals<br />Wind, water, and<br />ice erosion<br />Biological uptake, or absorption of particles, or precipitation<br />Eroded rock particles<br />Wind, water, and<br />ice erosion<br />River and wind transport and deposition<br />Sediments<br />Volcanic ash and igneous rocks <br />on land<br />Fallout of volcanic<br />ash over oceans<br />Compaction and<br />water loss<br />Subduction, melting,<br />and vulcanism<br />Scraped of and uplifted<br />ot subduction zone<br />Sedimentary rock on oceanic crust<br />Sedimentary rock on land<br />Seawater constituents<br />
  41. 41. Seawater constituents<br />
  42. 42. Movement and Transport<br />Diffusion – high concentrations  low concentration <br />Air vs. water<br />Mass transport – particles carried by fluid flow<br />
  43. 43. Diffusion<br />high concentration  low concentration <br />C = concentration<br />D = diffusion coefficient<br />x = length<br />t = time<br />
  44. 44. Mass Transport<br />high concentration  low concentration <br />
  45. 45. Physical properties of water<br /><ul><li>Viscosity
  46. 46. Reynolds number, Boundary Layers, and Mass transport
  47. 47. Density
  48. 48. Temperature</li></li></ul><li>Water as a fluid<br />Fluid (flu·id) French fluide, from Latin fluidus, from fluere to flow; akin to Greek phlyzein to boil over):<br /> having particles that easily move and change their relative position without a separation of the mass and that easily yield to pressure; capable of flowing. <br />
  49. 49. What is a fluid?<br />Viscosity (m): the resistance of a fluid to motion or internal friction<br />Reynolds number (Re): the ratio of inertial forces to viscous forces in a fluid<br />Density (r): the mass of a substance per unit volume <br />
  50. 50. Viscosity<br />m = 1 x 10-3 N s/m2<br />m = 50 N s/m2<br />At 20º C<br />m = 0.07 N s/m2<br />At 100º C<br />The viscosity of liquids can vary drastically and decreases rapidly with an increase in temperature.<br />
  51. 51. Reynolds number<br />
  52. 52. Reynolds number<br />Re = rUx/m<br />
  53. 53. Reynolds number<br />Re = rUx/m<br />Re = 108<br />Re = 1<br />
  54. 54. Copepod swimming<br />Low Re<br />
  55. 55. Boundary Layers and Mass Transport<br />Re = 101<br />Laminar<br />Turbulent<br />
  56. 56. Boundary Layers<br />
  57. 57. Boundary Layers and Mass Transport<br />Re = 103<br />Re = 108<br />
  58. 58. Density<br /> the mass of a substance per unit volume <br />
  59. 59. Temperature<br />
  60. 60. Temperature<br />
  61. 61. Thermoclines<br />

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