1. The Extraordinary Properties of Water Courtesy of Kate Morkeski http://genbio.biol.vt.edu/tapages/morkeski

2. http://madsci.wustl.edu/posts/archives/aug98/900528149.Bc.r.html The extraordinary properties of Water  A water molecule (H 2 O), is made up of three atoms: one oxygen and two hydrogen. http://www.e-spaces.com/broadcast/Water/scr2.html H H O

4. The extraordinary properties of Water At sea level, pure water boils at 100 °C and freezes at 0 °C. The boiling temperature of water decreases at higher elevations (lower atmospheric pressure). PV=nRT For this reason, an egg will take longer to boil at higher altitudes.

5. The extraordinary properties of Water  Cohesion  Adhesion  High Specific Heat  High Heat of Vaporization  Less Dense as a Solid

6. Cohesion Cohesion is the property of water that causes it to be attracted to itself. Surface tension, a measure of the strength of water’s surface, is the direct result of cohesion. The strong film on the surface of water is a result of the attraction between water molecules. This property allows insects to walk on the surface of water and the creation of waves.

7. Water strider

8. Cohesion

9. Adhesion Water will make hydrogen bonds with other surfaces such as glass, soil, plant tissues, and cotton. Water molecules will “tow” each other along when in a thin glass tube. This is called capillary action. This is the same process by which plants and trees remove nutrients from the soil, and paper towels soak up water..

10. Adhesion

11. 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.

12. http://www.ec.gc.ca/water/index.htm “Water vapor forms a kind of global ‘blanket’ which helps to keep the earth warm. Heat radiated from the sun-warmed surface of the earth is absorbed and held absorbed and held by the vapor.” by the vapor.”

13. 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.

14. High Heat of Vaporization Meteostat 5 water Vapor Imagery morning of 9/5/2004 Courtesty of http://www.goes.noaa.gov/

15. Water is Less Dense as a Solid Ice is less dense as a solid than as a liquid. Liquid water has hydrogen bonds that are constantly being broken and reformed. Frozen water forms a crystal-like lattice whereby molecules are set at fixed distances.

16. Water is Less Dense as a Solid Which is ice and which is water?

17. http://www.nyu.edu/pages/mathmol/modules/water/info_water.html Water is Less Dense as a Solid Water Ice

18. Density of water  If density of object is = to or < than water it will float.  If the object’s volume displaces an amount of water equal to the weight of the object 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.

20. The extraordinary properties of Water  Why talk about water?  In the fossil record, in what habitat do we first observe life?

21. Homeostasis  Steady state  Constant physiological condition of cells, organisms global ecosystems a. Makes a good insulator a. Makes a good insulator b. Resists temperature change b. Resists temperature change c. Universal solvent c. Universal solvent d. Coolant d. Coolant e. Ice protects against temperature extremes e. Ice protects against temperature extremes

22. Bond Types  Covalent  Hydrogen  Electrostatic  Van der Waals

23. Implication of Hydrogen Bonding  Ice floats: density of solid water is less than liquid  Cohesion: the intermolecular forces between particles of a substance, in this case, water  Adhesion: the intermolecular forces between two different substances, water and paper or glass or xylem.

24. Implication of Hydrogen Bonding  Specific heat: Water resists change in temperature. Heat energy is used to break H-bonds. Specific heat is amt. of heat that must be absorbed or lost for 1 g. of the substance to change temp. by 1C.  Heat of vaporization: amount of energy required to convert 1 gram of a substance from a liquid to a gas