Chapter three: Water and the fitness of the environment

This is pH Scale which is a graph of acid and base. The higher the number is that it means OH- is more than H+. For example: water's pH scale is 7 which is netural. If the pH number is smaller than 7 then the molecule has more OH- than H+ so it is acid.

Main questions:

What are the freezes and boil points of Celsius scale?

0 c and 100 c

What is the different between acid and base?
Acid is a substance that increases the hydrogen ion concentration of a solution.
Base is a substance that reduces the hydrogen ion concentration of a solution. Some bases reduce the H+ concentration directly by accepting hydrogen ions.

What is acid precipitation and what cause it?
Any rain, snow, or fog with a pH lower than pH 5.2 are called acid precipitation. Electric power plants that burn coal produce more of these oxides than any other single source. Winds carry the pollutants away, and acid rain may fall hundreds of kilometers away from industrial centers.

5 main facts:

Adhesion: The clinging of one substance to another, also plays a role.

Most cells are surrounded by water, and cells themselves are about 70-95% water.

Polar molecule means that the two ends of the molecule have opposite charges. The oxygen region of the molecule has a partial negative charge, and the hydrogen have a partial positive charge.

This evaporative cooling occurs because the “hottest” molecules, those with the greatest kinetic energy, are the most likely to leave as gas. It is as if the hundred fastest runners at a college transferred to another school; the average speed of the remaining students would decline.

Molecular mass is simply the sum of the masses of all the atoms in a molecule.

Summary:

The third is all about how those small molecules support all the lives on earth. Such as water molecules participate in many chemical reactions necessary to sustain life. Most cells are surrounded by water, and cells themselves are about 70-95% water. There are many phenomenon occur between different substances. Such as cohesion and adhesion are two basic phenomena. This chapter also mentions the important of heat and temperature in this world.
This chapter is basically all about the water on earth. Water plays a very important ruler on earth of climate and it is also important to any forms of lives. After reading this chapter that I realized we should be treasured all the resources on this planet.

Key terms:
1. 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.
2. 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.
3. Cohesion: The binding together of like molecules, often by hydrogen bonds.
4. Polar molecule-A molecule (such as water) with opposite charges on different ends of the molecule.
5. Specific heat: a substance is defined as the amount of heat that must be absorbed or lost for 1g of that substance to change its temperature by 1°C.
6. Heat of vaporization: is the quantity of heat a liquid must absorb for 1 g of it to be converted from the liquid to the gaseous state.
7. 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.
8.Molecular mass: is simply the sum of the masses of all the atoms in a molecule.
9. 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.
10. Hydrophilic: any substance that was an affinity for water.

Video: http://www.youtube.com/watch?v=QqjcCvzWwww&feature=related