Water Notes
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Water Notes Presentation Transcript

  • 1. Water
    The Universal Solvent
  • 2. Water Walk
    10 Different pictures/scenarios with brief description
    Write Down Number of Station and the scenario you are looking at.
    Start at the number of the station you are at
    Move clockwise
    Answer the following questions for each…
    How does the structure of water relate to this action/scenario?
  • 3. A little bit about water
    Water is the biological medium on Earth
    Universal Solvent
    Solvent: the substance that the solute (salt) is dissovled in (water)
    Solute: substance (salt) that is dissolved in a liquid
    Solution: when solutes are uniformly distributed throughout a water solvent
    All living organisms require water more than any other substance
    Most cells are surrounded by water, and cells themselves are about 70-95% water
    The abundance of water is the main reason the Earth is habitable
  • 4. The Solvent of Life
    A solution is a liquid that is a homogeneous mixture of substances
    A solvent is the dissolving agent of a solution
    The solute is the substance that is dissolved
    Water is a versatile solvent due to its polarity
    An aqueous solution is one in which water is the solvent
  • 5. Mixture, Solutions and Suspensions…oh my!
  • 6.
    • Mixtures
    • 7. physically, not chemically mixed compounds
    • 8. Not necessarily evenly distributed
    • 9. Homogenous
    • 10. Evenly distributed
    • 11. Cannot see the different parts
    • 12. Heterogenous
    • 13. Not uniformly distributed
    • 14. you can see the parts
    • 15. Solution
    • 16. Homogenous Mixture
    • 17. components are uniformly distributed
    • 18. Solutes and solvents
    • 19. Ex. Salt water
    • 20. Suspension
    • 21. Mixture of water and non-dissolved material
    • 22. Some of the most biologically important substances are both solutions and suspensions
    • 23. Ex. blood
  • 24. Water
    Chemical Formula
    • H2O
    How water is formed
    • Covalent compound
    • 25. Which atom has a stronger pull for electrons?
    The one that is bigger…oxygen
    Electrons are shared but they spend more time around Oxygen atom than the hydrogen atoms
    This makes water a…
    Polar Molecule
    • Uneven sharing of electrons
    • 26. slight positive charge by hydrogens
    • 27. Slight negative charge by oxygen
    • 28. POLARITY
    • 29. What do opposites do?
    Water molecules are attracted to other water molecules to form HYDROGEN BONDS
    • Weak attraction between hydrogen atom of one molecule and an oxygen, nitrogen or sulfur bond of another molecule.
  • LE 3-2
  • 30.
  • 31.
  • 32. Properties of water
    Versatility as a solvent
    Cohesiveand Adhesivebehavior
    Expansion uponfreezing
    Temperaturemoderation
  • 33. Water as the Universal Solvent
    Water is an effective solvent because it readily forms hydrogen bonds
    When an ionic compound is dissolved in water, each ion is surrounded by a sphere of water molecules, a hydration shell
    Water can also dissolve compounds made of nonionic polar molecules
    Even large polar molecules such as proteins can dissolve in water if they have ionic and polar regions
  • 34. LE 3-6

    Na+
    +

    +

    +


    Na+

    +
    +
    Cl–
    Cl–
    +


    +

    +


  • 35.
  • 36. LE 3-7a
    Lysozyme molecule
    in a nonaqueous environment.
  • 37. LE 3-7b
    Lysozyme molecule in a aqueous environment.
  • 38. Transpiration:
    Evaporation of water through the leaves of plants
    “stomata” are the tiny pores in the leaves of plants through which water (and oxygen) escapes…carbon dioxide enters here…
  • 39. Cohesive and Adhesivebehavior
    • Cohesion: whensimilarmolecules stick together (droplet of water)
    hydrogen bonds hold water molecules together
    Cohesion helps the transport of water against gravity in plants
    • Adhesion: whenunlikemolecules stick together (water on glass)
    Adhesion of water to plant cell walls also helps to counter gravity
    • How does water getfromroots to the leaves of a talltree?
  • Capillary Action
    DEF: The movement of water within the spaces of a porous material due to the forces of adhesion, cohesion, and surface tension
    Capillary action occurs when the adhesion to the walls is stronger than the cohesive forces between the liquid molecules.
  • 40. Capillary Action
    Think of what happens when you dip a paper towel in water
    What happens when you put celery in colored water
  • 41. Cohesion accounts for SURFACE TENSION
    Surface tension is a measure of how hard it is to break the surface of a liquid
  • 42. Heat and Temperature
    Kinetic energy is the energy of motion
    • Heat is a measure of the total amount of kinetic energy due to molecular motion
    • 43. Temperature measures the intensity of heat due to the average kinetic energy of molecules
  • Expansion Upon Freezing
    Liquid H2O WATER!
    Molecules of a liquid move how?
    Slide past each other!
    Hydrogen bonds between water molecules keep breaking and reforming
    Solid H2OICE!
    Hydrogen bonds become stuck on whatever nearby water molecule they are attached to
    Now molecules cannot slide past each other…therefore, they CANNOT pack densely together
    Liquid water is more dense, therefore…
    ICE FLOATS!!!
  • 44.
  • 45.
  • 46. What Happens When Hydrogen Bonds Form Between Water Molecules?
    • ENERGY is Released!!!
    • 47. Energy=HEAT
    • 48. So…when water freezes, is energy released or absorbed?
    • 49. RELEASED!
    • 50. When water freezes, its warms up its surroundings.
  • What Happens When Hydrogen Bonds Between Water Molecules Break???
    • This REQUIRES ENERGY!!!
    • 51. Energy or HEAT MUST Be absorbed
    • 52. To break hydrogen bonds, you just need to add heat…
  • Moderation of Temperature
    Water absorbs heat from warmer air and releases stored heat to cooler air
    Water can absorb or release a large amount of heat with only a slight change in its own temperature
  • 53. Weather and Water
    Coastal Areas
    During the hot day, the ocean/lake will absorb energy from the air so that it feels cooler
    At night, when the air is cooler, the water releases all the stored energy, making it warmer at night
    “moderate” temperature
    Inland areas (no water nearby)
    During the hot day, there is NO water to absorb heat so it is realllllyy hot (think desert)
    At night, no energy is release, so it gets very cold
  • 54. Water’s High Specific Heat
    The specific heat of a substance is the amount of heat that must be absorbed or lost for 1 gram of that substance to change its temperature by 1ºC
    Water’s high specific heat minimizes temperature fluctuations to within limits that permit life
    Heat is absorbed when hydrogen bonds break
    Heat is released when hydrogen bonds form
  • 55. Evaporative Cooling
    Evaporation is transformation of a substance from liquid to gas
    Heat of vaporization is the heat a liquid must absorb for 1 gram to be converted to gas
    As a liquid evaporates, its remaining surface cools, a process called evaporative cooling
    Evaporative cooling of water helps stabilize temperatures in organisms and bodies of water
    “Sweating” liquid to gas requires heat…this heat comes from inside our body
    What does the saying “It’s not the heat, it’s the humidity”mean?
    Humidity: water vapor in the air
    If there is more water in the air, it is harder for water molecules to evaporate off your skin…so how do you feel?
    Hot and sticky!
  • 56. Types of Attractions
    Covalent
    Ionic
    Hydrogen
    Van der Waals Forces
    Intermolecular force of attraction
    Due to uneven sharing of electrons in covalent bonds
    Slight attraction between oppositely charged regions of molecules that are closely packed together
    Holds large molecules together
  • 57. Hydrophilic and Hydrophobic Substances
    A hydrophilic substance is one that has an affinity (likes!) for water
    A hydrophobic substance is one that does not have an affinity (does NOT like; scared of) for water
  • 58. How water acts in solution
    Occasionally a water molecule dissociates (breaks up) into ions
    H2O H+ + OH-
    This happens to every one water molecule in a million in pure water…not very common
    The H+ immediately reacts with another water molecule in the solution to make a HYDRONIUM ion H30+
  • 59. Acids and Bases
    What do you know?
  • 60. Acids
    • An acid is any substance that increases the H+ concentration of a solution
    • 61. ADDS H+ ions to water
    • 62. taste sour
    • 63. turn cabbage juice red
    • 64. turn blue litmus paper red
    • 65. Strong acids (LOW pH)
    • 66. Dissociate completely in water
    • 67. Adds LOTS of H+ ions
    • 68. Hydrochloric acid HCl
    • 69. HCl H+ and Cl-
    • 70. Weak Acids (pH slightly below 7)
    • 71. Partially dissociate in water
    • 72. Only add a little bit of H+ ions
    • 73. Coffee, tomato juice, acetic acid
      H         O        |       //H--C—C
            |              H         O-
    CH3COOH = CH3COO- + H+
  • 74.
  • 75. Bases
    A base is any substance that reduces the H+ concentration of a solution
    ADDS HYDROXIDE ions (OH-) to water
    OH- ions bind to any free H+ ions to make…a molecule of water
    This does what to the concentration of H+ ions ion the water?
    DECREASE H+ ion concentration, therefore, making it basic
    Characteristics:
    taste bitter
    feels slimy
    turns cabbage juice yellow, green or blue depending upon the solution concentration
    turns red litmus paper blue
    Strong Bases (pH High- close to 14)
    Completely dissociate in solution
    Adds LOTS of OH- ion to solutions
    NaOH sodium hydroxide NaOH Na+ and OH-
    Weak Bases
    Partially dissociate in water
    Adds only a few OH- to solution
    Ammonia NH3
  • 76.
  • 77.
  • 78. Strong Acids and Bases
    HCl - hydrochloric acid
    HNO3 - nitric acid
    H2SO4 - sulfuric acid
    HBr - hydrobromic acid
    HI - hydroiodic acid
    HClO4 - perchloric acid
    LiOH - lithium hydroxide
    NaOH - sodium hydroxide
    KOH - potassium hydroxide
    RbOH - rubidium hydroxide
    CsOH - cesium hydroxide
    DISSOCIATE COMPLETELY
    What do you notice?
  • 79. The pH Scale
    • The pH of a solution is determined by the relative concentration of hydrogen ions H+
    • 80. So it is really measuring how acidic something is
    • 81. formula is..
    • 82. pH=-log[H+]
    • 83. Negative means opposite, this is why a low pH has MORE H+ ions
    • 84. [x] means concentration
    • 85. Acidic solutions have pH values less than 7
    • 86. More H+ ions
    • 87. Basic solutions have pH values greater than 7
    • 88. More OH- ions, less H+ ions
    • 89. Most biological fluids have pH values in the range of 6 to 8
  • 90. LE 3-8
    pH Scale
    0
    1
    Battery acid
    2
    Digestive (stomach)
    juice, lemon juice
    Vinegar, beer, wine,
    cola
    3
    Increasingly Acidic
    [H+] > [OH–]
    4
    Tomato juice
    Black coffee
    5
    Rainwater
    Urine
    6
    Neutral
    [H+] = [OH–]
    Pure water
    7
    Human blood
    8
    Seawater
    9
    10
    Increasingly Basic
    [H+] < [OH–]
    Milk of magnesia
    11
    Household ammonia
    12
    Household bleach
    13
    Oven cleaner
    14
  • 91. Buffers
    The internal pH of most living cells must remain close to pH 7
    Buffers are substances that minimize changes in concentrations of H+ and OH- in a solution
    Weak acids are a buffer for strong bases
    Weak bases are a buffer for strong acids
    Most buffers consist of an acid-base pair that reversibly combines with H+
  • 92. Acids and Bases in the Living Things
    Changes in concentrations of H+ and OH- can drastically affect the chemistry of a cell
    When you breath…
    CO2 + H2O ⇌ H+ + HCO-3
    Carbon dioixde water hydrogen ion bicarbonate ion
  • 93. The Threat of Acid Precipitation
    • Acid precipitation refers to rain, snow, or fog with a pH lower than 5.6
    • 94. Acid precipitation is caused mainly by the mixing of different pollutants with water in the air
    • 95. Acid precipitation can damage life in lakes and streams
    • 96. Effects of acid precipitation on soil chemistry are contributing to the decline of some forests
  • LE 3-9
    0
    More
    acidic
    1
    2
    Acid
    rain
    3
    4
    5
    Normal
    rain
    6
    7
    8
    9
    10
    11
    12
    13
    More
    basic
    14
  • 97. Hydrophilic and Hydrophobic Substances
    A hydrophilic substance is one that has an affinity (likes!) for water
    A hydrophobic substance is one that does not have an affinity (does NOT like; scared of) for water
  • 98. Law of Conservation of Energy and Matter
    Energy and Matter cannot be created or destroyed, only change form
    All atoms on one side of the equation must be accounted for on the other side of the equation
  • 99. All chemical formulas MUST balance.  
    C6H12O6 + O2------> CO2 + H2O
     Count atoms of each element on each side.
    Is it balanced (does it follow law of conservation of matter?)
    Increase number of molecules of each compound to balance.
    Change COEFFICENT
    Coefficient is the number before the compound (only number you can change)
    C6H12O6 + 6O2------> 6CO2 + 6H2O
    (glucose)     + (oxygen)-------(carbon dioxide)  + (water)
    6 carbons on the left 6 carbons on the right
    12 hydrogen on the left 12 hydrogen on the right
    18 oxygen on the left 18 oxygen on the right