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

The extraordinary properties of Water A water molecule (H2O), is made up of three atoms: one oxygen and two hydrogen. H O http://madsci.wustl.edu/posts/archives/aug98/900528149.Bc.r.html http://www.e-spaces.com/broadcast/Water/scr2.html 1

Hydrogen bonds are very strong and form polar molecules (bond dipoles) Hydrogen bonds are very strong and form polar molecules (bond dipoles). This is due to the O-H bonds and secondary attractions. (Can also form with N-H and H-F) 10

Cohesion 1

The extraordinary properties of Water At sea level, pure water boils at 100 °C and freezes at 0 °C. Other physical properties include: Cohesion Adhesion High Specific Heat High Heat of Vaporization Less Dense as a Solid 1

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. 1

Water strider 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.

Adhesion Water will form strong secondary bonds with other surfaces such as glass, soil, and plant tissues. Moving water molecules will “tow” each other along. 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. . 1

“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 by the vapor.” http://www.ec.gc.ca/water/index.htm 1

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. 1

High Heat of Vaporization Meteostat 5 water Vapor Imagery morning of 9/5/2004 Courtesty of http://www.goes.noaa.gov/ 1

Water is Less Dense as a Solid Which is ice and which is water? The solid form of water is directly related to hydrogen bonds. 1

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 so they will float with a ratio of more ice above the surface than that of an ice cube.

Water and heat transfer… Specific heat: Heat energy is used to break H-bonds. Specific heat is J/g°C. Heat of vaporization: amount of energy required to convert 1 gram of a substance from a liquid to a gas and vice versa. Hv = 2260 J/g Heat of Fusion: amount of energy required to convert 1 gram of a substance from a liquid to a solid and vice versa. Hf = 334 J/g 13