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Unique properties of water overview

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Hydrogen bonds, crystal lattice, specific heat, etc.

Hydrogen bonds, crystal lattice, specific heat, etc.

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  • 1. The Water Planet
  • 2.
    • 97% of all water on our planet is in the oceans.
    • 3. Fresh water represents the remaining 3% (2/3 is snow and ice in glaciers / polar ice caps).
    • 4. Liquid and solid water cover roughly 3/4 of Earth's surface area.
    • 5. 29% of the earth’s surface is above sea level (71% is below )
  • Unique properties of water
    Absorbs or releases more heat than most other substances for every temperature degree of change
    Water is a good solvent and can dissolve more substances than other fluids, even rocks
    Water exists in 3 physical states that can power thunderstorms/hurricanes and help transport the sun's energy, nutrients, and organisms
  • 6. More than half the world's population live within 60km of a coastline
    South Florida, USA
  • 7. Overview
    Chemical properties of water
    H bonds
    Ice
    Salinity and Sources
    Physical properties of water
    Biomechanics
    Density
    Temperature
  • 8. Chemical properties of water
    Hydrogen Bonds
    Crystalline Structure
    Surface Tension
    Tensile Strength
    Specific Heat
    Evaporation
    Molecular Interactions
    Movement and Transport
  • 9. Chemical properties of water
    Hydrogen Bonds
    Crystalline Structure
    Surface Tension
    Tensile Strength
    Specific Heat
    Evaporation
    Molecular Interactions
    Movement and Transport
  • 10. Hydrogen Bonds
    d-
    O
    H
    H
    d+
    d+
  • 11. Hydrogen Bonds
  • 12. Hydrogen Bonds
    3 physical states of water:
    WATER VAPOR
  • 13. Crystalline Structure
  • 14. Crystalline Structure
  • 15. Ice
  • 16. d-
    O
    H
    H
    d+
    d+
    Surface tension
    Water has high surface tension due to lateral and downward attraction between individual molecules, which stretches the water's surface, creating a thin skin
  • 17. Surface tension
    Water has high surface tension due to lateral and downward attraction between individual molecules, which stretches the water's surface, creating a thin skin
  • 18. Surface tension
    • Water striders can walk upon the water's surface.
    • 19. Members of the neuston depend upon the surface film of water for transport and food.
    • 20. Liquid water on surfaces to which it does not adhere well "beads-up."
    • 21. Surface tension of the water allows wind to push against it, generating waves in large water bodies.
    • 22. [Detergents reduce the surface tension of water (by as much as 70%) and allows it to spread out on a surface.]
  • Tensile strength
    Water is strong under tension.
    The force needed to pull pure water apart can be as much as 3 x 107 Newtons/m2
    120 lbs = 530 Newtons
    Limpet attachment strength = 1 x 106 Newtons/m2
  • 23. Specific heat
    Water can absorb a great deal of energy which goes to breaking hydrogen bonds but does not lead to measurable temperature increases.
    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.
  • 24. Evaporation
     A water molecule makes the transition from a liquid phase into a gas phase.
    Because the escaping molecule had a higher than average energy level, it leaves the liquid cooler (lower in energy) upon evaporation.
  • 25. Hydrogen Bonds - Summary
    • High heat capacity (1 cal/g/°C);
    • 26. Heat of vaporization (540 cal/g);
    • 27. Heat of fusion (-80 cal/g);
    • 28. Solid less dense than liquid phase;
    • 29. High surface tension
  • Molecular interactions
    Solutes
    Dissociation of Water Molecules
    KD = [H+][OH-]/[H2O] = 1.8 x 10-16M
    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)
  • 30. pH of solutions
    pH - an index of the relative concentration of H+ ions in solution
    [H+] = [OH-] = 10-7M in pure water([H2O] = 55 M)
    pH º -log10[H+]
    In pure water, pH = 7
  • 31. pH of solutions
    The pH scale ranges from 0 to 14
    The higher the pH, the lower the [H+] (alkaline, basic solutions have a high pH)
    The lower the pH, the higher the [H+] (acidic solutions have a lower pH)
  • 32. pH of solutions
    Examples:
    Gastric juice = 1.0 Seawater  8.0
    Orange juice = 4.3 Urine = 6-8.0
    Blood plasma = 7.4 Ammonia = 12.0
  • 33. pH and the sea
    A difference in pH from 8 to 7.8 can significantly decrease coral growth rates
    Increased CO2 in the atmosphere lowers pH
    Active photosynthesis and nitrogenous waste excretion can increase local pH
  • 34. Water as a polar solvent and Salinity
    Strong Electrolytes (substances that dissociate completely when dissolved in water - ions)
    Salts consist of ions:
          NaCl ® Na+ + Cl- salt
                        HCl ® H+ + Cl- strong acid
                          NaOH ® Na+ + OH- strong base
    For strong electrolytes, KDȴ
  • 35. Water as a polar solvent
    Weak Electrolytes (substances that dissociate in water only to a small extent (KD»10-3M to 10-11M)
    H2CO3 H+ + HCO3- KD = 1.7 x 10-4M
    KD»10-3M to 10-11M
  • 36. CO2(g)            CO2(aq)
    (CO2 from the atmosphere
    dissolves into seawater)
    CO2(aq) + H2O(l)            H2CO3(aq)
    (Carbonic acid)
    H2CO3           H+ + HCO3-KD = 4.2 × 10-7
    HCO3-    H+ + CO32-KD = 4.8 × 10-11
    CaCO3(s) + 2 H+(aq)            Ca2+(aq) + H2CO3(aq)
    Carbon dioxide-carbonate equilibrium
    bicarbonate
    carbonate
    • High CO2= low [CO32- ]
    Ocean acidification
  • 37. Water as a polar solvent
    Because of its small size and polar nature, water dissolves many materials, more than any other liquid
    Oceans of water act as sink for CO2 molecules – leads to acidification
    Seawater contains almost every known naturally occurring element
  • 38. Seawater constituents
    Component
    Concentration
    Percentage of Salinity
    chloride 
    18.98 
    55.03 
    sodium 
    10.56 
    30.59 
    sulfate 
    2.65 
    7.68 
    magnesium 
    1.27 
    3.68 
    calcium 
    0.40 
    1.18 
    potassium 
    0.38 
    1.11 
    bicarbonate 
    0.14 

  • 39. Seawater constituents
    • Average ocean water has a salinity of 35.0
    • 40. This means that 1000 g of average seawater contains 965 g of water and 35 g of salts.
  • Dissolved
    chemicals
    Wind, water, and
    ice erosion
    Biological uptake, or absorption of particles, or precipitation
    Eroded rock particles
    Wind, water, and
    ice erosion
    River and wind transport and deposition
    Sediments
    Volcanic ash and igneous rocks
    on land
    Fallout of volcanic
    ash over oceans
    Compaction and
    water loss
    Subduction, melting,
    and vulcanism
    Scraped of and uplifted
    ot subduction zone
    Sedimentary rock on oceanic crust
    Sedimentary rock on land
    Seawater constituents
  • 41. Seawater constituents
  • 42. Movement and Transport
    Diffusion – high concentrations  low concentration
    Air vs. water
    Mass transport – particles carried by fluid flow
  • 43. Diffusion
    high concentration  low concentration
    C = concentration
    D = diffusion coefficient
    x = length
    t = time
  • 44. Mass Transport
    high concentration  low concentration
  • 45. Physical properties of water
    • Viscosity
    • 46. Reynolds number, Boundary Layers, and Mass transport
    • 47. Density
    • 48. Temperature
  • Water as a fluid
    Fluid (flu·id) French fluide, from Latin fluidus, from fluere to flow; akin to Greek phlyzein to boil over):
     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.
  • 49. What is a fluid?
    Viscosity (m): the resistance of a fluid to motion or internal friction
    Reynolds number (Re): the ratio of inertial forces to viscous forces in a fluid
    Density (r): the mass of a substance per unit volume
  • 50. Viscosity
    m = 1 x 10-3 N s/m2
    m = 50 N s/m2
    At 20º C
    m = 0.07 N s/m2
    At 100º C
    The viscosity of liquids can vary drastically and decreases rapidly with an increase in temperature.
  • 51. Reynolds number
  • 52. Reynolds number
    Re = rUx/m
  • 53. Reynolds number
    Re = rUx/m
    Re = 108
    Re = 1
  • 54. Copepod swimming
    Low Re
  • 55. Boundary Layers and Mass Transport
    Re = 101
    Laminar
    Turbulent
  • 56. Boundary Layers
  • 57. Boundary Layers and Mass Transport
    Re = 103
    Re = 108
  • 58. Density
     the mass of a substance per unit volume
  • 59. Temperature
  • 60. Temperature
  • 61. Thermoclines

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