Monday, September 8, 2008

Chapter 3: Water and the Fitness of the Environment!
Water contributes to the fitness of the environment to support life. Here are some examples of this idea:

-Living cells are 70%-95% water
-Water covers about ¾ of the earth
-In nature, water naturally exists in all 3 physical states of matter- solid, liquid and gas


What are the effects of water’s polarity?

- The structure of water is key to its special properties. Water is made up of one atom of oxygen and two atoms of hydrogen, bonded to form a molecule that looks like this:


- The fact that water is v-shaped means that it is polar(the opposite ends of the molecule have opposite charges). The end bearing the oxygen atom has a slightly negative charge, whereas the end bearing the hydrogen atom has a slightly positive charge.

-This is what makes water able to form hydrogen bonds. The slightly negative oxygen atom from one molecule is attracted to the slightly positive hydrogen end of another water molecule. Each water molecule can form a maximum of 4 hydrogen bonds at a time.


What roles do Adhesion and Cohesion have in a Water Molecule?

-Adhesion is the clinging of one substance to a water molecule. Water is very adhesive because of its hydrogen bonds. The property of adhesion allows water to travel up the stem of plants. In Transpiration, water evaporates from the leaves of plants.



-Since hydrogen bonding virtually attaches the water molecules one to another to form a long chain up through the cells of plants, the water is pulled up in a chain through the xylem by Capillary Action.

-Because of water’s Cohesion, water molecules have the ability to cling to each other, as well.


What is Surface Tension?

-Surface Tension is a measure of how difficult it is to stretch or break the surface of a liquid.


What is Specific Heat?

- Water is responsible for insulating the earth, and moderating its temperature. It is able to do this because of its very high Specific Heat. Specific heat is the amount of heat required to raise or lower the temperature of a substance by 1 degree celcius. The specific heat of water is 1 cal/g/C.

- Water has very high specific heat, so it takes more heat energy to raise the temperature of water, and more energy must be lost from water before its temperature will decrease.

- The reason for water’s high specific heat is its hydrogen bonds. But, this specific heat makes the temperature of the earth’s oceans relatively stable and able to support vast quantities of both plant and animal life.

1 comment:

SMABiology said...

Kicki,

Outstanding! You delineated the concepts well and summarized in a manner that is outline friendly and easy to read.