water ppt 2
Post on 20-Aug-2015
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The extraordinary properties of Water
• Cohesion• Adhesion• High Specific Heat• High Heat of Vaporization• Less Dense as a Solid
http://www.realeyz.com/photo/macro/photos/leaf_drops.jpg
CohesionCohesion is the property of water that causes it to be attracted to itself.
Capillarity Water molecules will “tow”
each other along when in a thin glass tube.
AdhesionAttraction between molecules of different substances
Ex: glass and water
http://staff.um.edu.mt/rlib1/sm/wpe32.jpg
Cohesion-Adhesion Theory
-As water evaporates from leaves, it tugs on the water molecules below-Cohesion and adhesion pull water up and replace missing water molecules-Water enters the roots by osmosis
www.emc.maricopa.edu/.../BioBookPLANTHORM.html
Did you ever wonder: How does water move from roots to leaves when a tree doesn’t have a heart to pump the water?
• Surface tension measures the strength of water molecules attracting to one another.
• This property allows insects to walk on the surface of water and the creation of waves.
Surface Tension
• Water will make hydrogen bonds with other surfaces such as glass, soil, plant tissues, and cotton.
High Specific Heat
• Water resists temperature change, both for heating and cooling.
•Water can absorb or release large amounts of heat energy with little change in actual temperature.
High Heat of Vaporization
• In order for water to evaporate, hydrogen bonds must be broken. As water evaporates, it removes a lot of heat with it.
• Thus, the heat of vaporization refers to the amount of energy required to convert water from a liquid to a gas.
Density of Ice• Most solids are more dense than their liquids• This makes solids sink
• Ice is less dense than liquid water• Due to H-Bonds• Important to life because bodies of water freeze top down
• Allows life to survive below
http://shiftingbaselines.org/blog/images/Iceberg.jpg
Density of water
• If density of object is = to or < than water it will float.
• Displacement is how steel ships can float even though the density is greater.
• Density of pure water is 1.0• Density of pure ice is 0.92. • Density of sea water is 1.03.
• Icebergs are made of pure water will float with a ratio of more ice above the surface than that of an ice cube.
pH ScaleMeasurement of the concentration of hydrogen ions
Acid:High concentration of [H+](or hydronium ion);low conc. of [OH-]
Base:High [OH-](a.k.a. hydroxide ion);low [H+]
pH = -log [H+]
Stomach Acid = pH 2
Homeostasis
• Steady state• Constant physiological
condition of cells, organisms global ecosystems– a. Makes a good insulator– b. Resists temperature change– c. Universal solvent– d. Coolant
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