1. Environmental Science 2010

2. PERIODIC TABLE

3. Living Matter made up of: C = Carbon H = Hydrogen N = Nitrogen O = Oxygen P = Phosphorous S = Sulfur

4. Importance of pH=Homeostasis 1. All living organisms require specific pH ranges in order for their cells to function properly. 2. pH – potential Hydrogen (H+) in water or whatever liquid is being measured.

5. Importance of pH 3. In more everyday terms, pH is a unit of measure for determining if a liquid is acidic or basic (alkaline). 4. pH is measured on a scale of 0.0 to 14.0. a. Numbers < 7.0 = acidic b. Numbers > 7.0 = basic c. A pH of 7.0 indicates a neutral liquid

6. pH: Acids and Bases Acid—any substance that releases H + (hydrogen ions) when mixed with water Base—any substance that releases OH - (hydroxide ions) when mixed with water

7. Acids and Bases  The stronger an acid is the lower its pH number.  The stronger a base is the higher its pH number.

8. Acids = H+ ion Examples of acids Vinegar and battery acid are examples of acids. Acids have the following properties:  Acids taste sour.  They react strongly with metals.  Strong acids are dangerous and can burn your skin.

9. Bases = OH- ion Baking soda and bleach are examples of basic substances, or bases. Bases have the following properties:  Bases taste bitter.  They feel slippery.  Strong bases can burn your skin.

10. More on pH The pH scale is logarithmic. Means is that a change of one pH unit reflects a tenfold change in H+ concen or acidity. Some examples can help illustrate how this works: a. Liquid with a pH of 6.0 = 10X more acidic than pure water (pH=7.0). b. Liquid with a pH of 5.0 =100 X(10x10) more acidic than pure water.

11. More on pH… c. Liquid with a pH of 8.0 is ten times more basic than pure water. d. Liquid with a pH of 9.0 is one hundred times more basic than pure water.