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03 water text

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Water, Polarity, etc.

Water, Polarity, etc.

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    03 water text 03 water text Presentation Transcript

    • 1
      Water and the Fitness of the Environment
    • 2
      Importance of water
      Overview: The Molecule That Supports All of Life
      Water is the biological medium here on Earth
      All living organisms require water more than any other substance
    • 3
      Water Facts
      The polarity of water molecules results in hydrogen bonding
      The water molecule is a polar molecule
    • 4
      –
      Hydrogenbonds
      +
      H
      –
      +
      H
      +
      –
       –
      +
      Figure 3.2
      Water’s Polarity
      The polarity of water molecules
      Allows them to form hydrogen bonds with each other
      Contributes to the various properties water exhibits
    • 5
      Properties of water
      Water conducting cells
      Four emergent properties of water contribute to Earth’s fitness for life
      3. Water moderates air temperature because it has a high specific heat, which allows it to minimize temperature fluctuations to within limits that permit life
      1. Cohesion - Like molecules bonding to each other (water attracting other water molecules)
      2. Surface tension
      Is a measure of how hard it is to break the surface of a liquid
      4. Water is a versatile solvent due to its polarity
    • 6
      Insulation of Bodies of Water by Floating Ice
      Solid water, or ice
      Is less dense than liquid water
      Floats in liquid water
      Life can exist under the frozen surfaces of lakes and polar seas
    • 7
      Negative oxygen regions of polar water molecules are attracted to sodium cations (Na+).

      Na+
      +
      +

      +


      Positive hydrogen regions of water molecules cling to chloride anions (Cl–).
      Na+

      +
      +
      Cl –
      Cl–
      +


      +

      +


      Figure 3.6
      The different regions of the polar water molecule can interact with ionic compounds called solutes and dissolve them
    • 8
      Hydrophilic and Hydrophobic Substances
      A hydrophobic substance
      Does not have an affinity for water
      A hydrophilic substance
      Has an affinity for water
    • 9
      Acids and Bases
      Dissociation of water molecules leads to acidic and basic conditions that affect living organisms
      Organisms must maintain homeostasis in the pH of their internal and external environments
    • 10
      +

      H
      H
      H
      +
      H
      H
      H
      H
      H
      Hydroxide
      ion (OH–)
      Hydronium
      ion (H3O+)
      Figure on p. 53 of water dissociating
      Effects of Changes in pH
      Water can dissociate Into hydronium ions (H+ or H3O+)and hydroxide (OH-) ions
      Changes in the concentration of these ions Can have a great affect on pH in living organisms
    • 11
      Acids and Bases
      An acid
      Is any substance that increases the hydrogen ion concentration of a solution
      A base
      Is any substance that reduces the hydrogen ion concentration of a solution
    • 12
      The pH Scale
      Scale goes from 0-14 with 7 neutral
      The pH of a solution Is determined by the relative concentration of hydrogen ions
      Difference of 10X in hydrogen ion concentration between any two pH values
      Acids have a higher number of H+ ions than a base
      Acids produce H+ ion in solution
      Bases produce OH- ions in solution
    • 13
      The pH scale and pH values of various aqueous solutions
      pH Scale
      0
      1
      Battery acid
      2
      Digestive (stomach)
      juice, lemon juice
      Vinegar, beer, wine,
      cola
      3
      Increasingly Acidic
      [H+] > [OH–]
      4
      Tomato juice
      5
      Black coffee Rainwater
      6
      Urine
      Neutral
      [H+] = [OH–]
      7
      Pure water
      Human blood
      8
      Seawater
      9
      10
      Increasingly Basic
      [H+] < [OH–]
      Milk of magnesia
      11
      Household ammonia
      12
      Household bleach
      13
      Oven cleaner
      14
      Figure 3.8
    • 14
      Buffers
      The internal pH of most living cells
      Must remain close to pH 7
      Buffers
      Are substances that minimize changes in the concentrations of hydrogen and hydroxide ions in a solution
      Consist of an acid-base pair that reversibly combines with hydrogen ions
      Made by organisms
    • 15
      0
      1
      Moreacidic
      2
      3
      Acidrain
      4
      5
      Normalrain
      6
      7
      8
      9
      10
      11
      12
      13
      Morebasic
      14
      Figure 3.9
      Acid precipitation
      Can damage life in Earth’s ecosystems
    • 16
      Moles and Molarity
      A mole
      Represents an exact number of molecules of a substance in a given mass
      Molarity
      Is the number of moles of solute per liter of solution
    • 17
      God created water before life
      1 In the beginning God created the heavens and the earth.  2 Now the earth was formless and empty, darkness was over the surface of the deep, and the Spirit of God was hovering over the waters.