Chapter three: Water and the fitness of the environment

Q1: How does the water affect the environment?
A1: Almost all the living things contain water. They release and gain energy by transfer water. Water can control climate by evaporating.
Q2: How is water compounded?
A2: A water molecule has one oxygen atom and two hydrongen atoms. And hydrogen bonds between eater molecules.
Q3: How important is water of the planet Earth?
A3: Three-quater of earth surface is coverd with water. Water is the resource of living things.Living things can not live without water.

Five Facts:
1. Because oxygen is more electronegative, hydrogen bonds are founded.
2. heat is form of energy measured by volume.
3. evaporation is a process that from liquid to air gas
4. hyfrophilic is something likes water; hydrophobic is something repel water
5. acid has high hydrogen concentration; base reduces hydrogen concentration

Figure

Because of the cool environment, ice crystal is founded. All the hydrogen bonding in specific shape, so the dense is less than liquid. So the ice can float above the liquid water. If the environment becomes warmer, hydrogen bonds break and re-from in free.

Summary:
Water has three phsical states: solid, liquid, and gas. Hydrogen bond has cohesion to transfer water against gravity. And water has strong surface tension. Kinekic energy is the energy of motion. Heat is form of energy. A calorie is the amount of heat it takes the temperature of 1g of water by 1℃. Water's specific heat is 1cal. Heat must be absorbed in order to break hydrogen bonds, and released by bonds form. Water evaporation can help cool down. Heat of vaporization is the quantity of heat a liquid must absorb for 1g of it to be converted from the liquid to the gas. At 4℃, water has the biggest density. A solution is a liquid with solvent and solute. An aqueous solution is one in which water is the solvent. Molecular mass is the sum of its atomic mass.
Hydrogen ion, H+. Hydroxide ion OH-. Hydronium ion H3O+. ph is scale of acid and base. H+ and OH- concentrations at 10-14. So the ph is 1-14. 7 is neutral at 25℃. Buffers can control changes of H+ and OH- in blood.

key terms:

1. buffer-A substance that consists of acid and base forms in a solution and that minimizes changes in pH when extraneous acids or bases are added to the solution.


2. calorie (cal)-The amount of heat energy required to raise the temperature of 1 g of water by 1°C; also the amount of heat energy that 1 g of water releases when it cools by 1°C. The Calorie (with a capital C), usually used to indicate the energy content of food, is a kilocalorie.


3. cohesion-The binding together of like molecules, often by hydrogen bonds.


4. evaporative cooling-The process in which the surface of an object becomes cooler during evaporation, owing to a change of the molecules with the greatest kinetic energy from the liquid to the gaseous state.


5. heat of vaporization-The quantity of heat a liquid must absorb for 1 g of it to be converted from the liquid to the gaseous state.


6. hydrophilic- Having an affinity for water.


7. hydrophobic-Having an aversion to water; tending to coalesce and form droplets in water.


8. polar molecule-A molecule (such as water) with opposite charges on different ends of the molecule.


9. specific heat-The amount of heat that must be absorbed or lost for 1 g of a substance to change its temperature by 1°C.


10. surface tension-A measure of how difficult it is to stretch or break the surface of a liquid. Water has a high surface tension because of the hydrogen bonding of surface molecules.

video:

http://www.youtube.com/watch?v=LGwyBeuVjhU

hydrogen bond