Water

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Water
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Describe Water (46NBtop)

• How would you describe water to someone who had
  never seen it before?
• You might say that pure water has no color, no
  taste, and no odor. You might even say that water
  is a rather plain, ordinary substance.
• If you asked a chemist to describe water, the
  chemist would say that water is very unusual. Its
  properties differ from those of most other
  familiar substances.

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NB Setup

• NB44 - Hydrosphere Unit Page
• (label decorate)
• NB45 - Hydrosphere Objectives Tracker
• NB46 Describe Water /
• NB47 - Unique Properties of Water Webquest
• NB48 - Unique Properties of Water Foldable
• NB49 Properties of Water Station Lab
• NB50 Frayer Diagrams Cohesion/Adhesion

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Why is water so Important?

• All life on Earth depends on water
• Our fresh water resources are scarce
• Global warming is effecting the hydrosphere
• Different types of pollution are contaminating
  all of our water
• Etc, etc, etc.
• Now. Lets look at what makes water so special
  in the first place.

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Properties of Water
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foldable Instructions

• Fold your white paper into a 3-fold brochure
• Title is Unique Properties of Water
• Label inside 3 section
• Universal Solvent/Solubility
• Cohesion/Adhesion (Capillary Action!!)
• Surface Tension
• Label two outside sections
• Polarity/Specific Heat
• Density/Buoyancy

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foldable Instructions

• What goes in our foldable?
• Facts!
• Definitions!
• Pictures!
• Be creative! Own it!
• What seems important TO YOU??

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Polarity of Water

• In a water molecule two hydrogen atoms form
  single polar covalent bonds with an oxygen atom.
• A water molecule is a polar molecule with
  opposite ends of the molecule with opposite
  charges.

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Water has a variety of unusual properties because
of attractions between these polar molecules.

• Each water molecule can form hydrogen bonds
  with up to FOUR neighbors.
• Gives water more structure than other liquids
  and therefore causes lots of interesting things
  to happen

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foldable Instructions

• What goes in our foldable for Polarity?
• Facts!
• Definitions!
• Pictures!
• Be creative! Own it!
• What seems important TO YOU??

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Capillary Action
Now, how does that work??
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Cohesion Adhesion
Hydrogen bonds hold water together, a phenomenon
called .
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Cohesion

• Co-hesion
• Co- share
• -hesion bonded example -gt (adhere)
• So
• Cohesion refers to waters attraction to other
  water molecules.

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Adhesion

• Adhesion refers to attraction to other
  substances.
• Water is adhesive to any substance with which it
  can form hydrogen bonds.

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Trees have specialized structures to transport
water - xylem and phloem plumbing Water
molecules are dragged from the roots to the top
of the tree by capillary action and cohesion!
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Capillary action
water evaporates from leaves transpiration
adhesion, cohesion and capillary action
water taken up by roots
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Surface Tension

• Have you ever watched water striders (spiders!!!)
  skate across the surface of a pond without
  sinking?
• They are supported by the surface tension of the
  water.

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• Surface tension is the tightness across the
  surface of water that is caused by the polar
  molecules pulling on one another.
• (its related to cohesion)
• Some animals can stand, walk, or run on water
  without breaking the surface.

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• Water has a greater surface tension than most
  other liquids because hydrogen bonds among
  surface water molecules resist stretching or
  breaking the surface.
• Water behaves as if covered by an invisible
  film.
• Where else have you seen surface tension in
  action?

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Specific Heat

• It is a steamy summer day. The air is hot, the
  sidewalk is hot, and the sandy beach is hot. But
  when you jump into the ocean, the water is
  surprisingly cool! If you go for an evening swim,
  however, the water is warmer than the cool air.

WHY?
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Because.

• Water has a HIGH Specific Heat.
• Specific Heat is the amount of heat that must be
  absorbed or lost for one gram of a substance to
  change its temperature by 1oC.

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Three-fourths of the earth is covered by water.
The water serves as a large heat sink responsible
for
The Earth is over 75 water!

1. Prevention of temperature fluctuations that are
   outside the range suitable for life.
2. Coastal areas having a mild climate
3. A stable marine environment

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Universal Solvent
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Universal Solvent

• What happens when you make a fruit drink from a
  powdered mix?
• homogeneous solution.
• In an aqueous solution, water is the solvent.
• Shhh.Water is not really a universal solvent,
  but it is very versatile because of the polarity
  of water molecules.

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Solvent for Life

• Can be either
• Solute (if its not main ingredient)
• Solvent ( Aqueous solution )
• Hydrophilic (H20 loving)
• Ionic compounds dissolve in water
• Polar molecules (generally) are water soluble
• Hydrophobic (H20 phobic)
• Nonpolar compounds

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• Cohesion and solubility allow.
• Water to transport molecules dissolved in it
• Blood, a water-based solution, transports
  molecules of nutrients and wastes organisms
• Nutrients dissolved in water get transported
  through plants
• Unicellular organisms that live in water absorb
  needed dissolved substances

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Density of Water

• Most dense at 4oC
• Contracts until 4oC
• Expands from 4oC to 0oC

• The density of water
• Prevents water from freezing from the bottom up.
• Ice forms on the surface firstthe freezing of
  the water releases heat to the water below
  creating insulation.
• Makes transition between season less abrupt.

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Solid water (ice) is less dense than liquid

• Ice is less dense than water the molecules are
  spread out to their maximum distance
• Density mass/volume

same mass but a larger volume
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How does ice float?

• Ice is Buoyant
• It floats on top of the more dense liquid water
• But what is Buoyancy?

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Oceans and lakes dont freeze solid because ice
floats

• water expands as it solidifies
• water reaches maximum density at
  4-degrees C
• water freezes from the top down
• organisms can still live in the water underneath
  the ice during winter

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Water is Transparent

• The fact that water is clear allows light to pass
  through it
• Aquatic plants can receive sunlight
• Light can pass through the eyeball to receptor
  cells in the back

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Lets Wrap it up!

• Ticket out the door
• 3/2/1 3 things you learned, 2 questions, 1
  favorite or Least favorite thing about todays
  lesson
• H.W. - Brochure
• Follow given rubric, and use notes from today
• Due Mon/Tues

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Warm-Up - 46NBbottom

• What properties of water do you feel make it a
  Unique/Special Substance? Explain and justify
  your response.

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Frayer Diagrams
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Stations on Water Properties
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Lets Wrap it up!

• Ticket out the door Take 2
• 3/2/1 3 things you learned, 2 questions, 1
  favorite or Least favorite thing about todays
  lesson
• Psst! (did your questions from last lesson get
  answered? Let me know!!)
• H.W. Frayer Diagrams completed
• Also
• Complete all station reports, if not completed in
  Class.
• Notebooks due Friday for NB check!