1. Biological Buffers

2. Buffers Allow biological fluids to maintain relatively constant pH despite additions of acids or bases.

3. For Example: Blood Human blood is normally pH 7.4

4. If you added a strong acid to water it could change from pH 7 to pH 2 very quickly. When a strong acid is added to blood it only changes from pH 7.4 to 7.3. WHY?

5. Buffers Minimizes the changes in concentrations of H+ and OH- Carbonic acid forms when carbon dioxide reacts with water

6. What’s the diff? ACIDS ARE H+ DONORS (also remove OH-) BASES ARE H+ ACCEPTORS (also add OH-)

7. Acid or Base? HCl H 2 SO 4 NaOH

8. Acid or Base? HCl H 2 SO 4 base acid base NaOH

9. Carbonic Acid H 2 CO 3 is an H + donor (Acid) Bicarbonate Ion HCO 3 - is an H + acceptor (Base) Notice the double arrow in the equation above: that means the reaction can go both ways.

10. Buffer Equilibrium H 2 CO 3 is in equilibrium with HCO 3 − + H + H 2 CO 3 HCO 3 − + H + (the direction of the reaction will go to making the concentrations even on both sides of the arrows) If you have a lot of carbonic acid the reaction will go toward the right. If you have a lot of H + ions the reaction will go to the left.

11. If H+ concentration falls, That means the pH rises That means it is becoming more basic The reaction proceeds to the right as the carbonic acid dissociates to replenish H+ ions

12. If H+ concentration rises, That means the pH lowers That means it is becoming more acidic The reaction proceeds to the left as the bicarbonate ion removes the H+ ions from the blood to form carbonic acid

13. OCEAN ACIDIFICATION Carbonic acid is also formed in the ocean when atmospheric CO 2 reacts with water. This will remove the carbonate ion concentration in the ocean. NOTE CO 2 LEVEL INCREASE.

14. But marine animals need carbonate ions for: coral and shells

16. What causes the increase of carbon dioxide levels in the atmosphere? Burning of fossil fuels is a major source Carbon Dioxide + rain water carbonic acid Sulfur oxides + rain water sulfuric acid Nitrogen oxides + rain water nitric acid FORMS ACID PRECIPITATION: Refers to rain, snow, or fog of a pH lower than 5.2 (NORMAL RAIN IS ABOUT pH 5.6) Burning of fossil fuels is a major source Carbon Dioxide + rain water carbonic acid Sulfur oxides + rain water sulfuric acid Nitrogen oxides + rain water nitric acid FORMS ACID PRECIPITATION: Refers to rain, snow, or fog of a pH lower than 5.2 (NORMAL RAIN IS ABOUT pH 5.6)

17. ACID PRECIPITATION

18. Why is the pH lower in the East?

19. Effects of Acid Precipitation Thinner egg shells Thinner snail shells Fewer songbirds that eat snails Destroys leaves

20. More Negative Effects Fish are very susceptible to pH changes. Plankton and small invertebrates and young marine life are especially vulnerable. Erode statues and buildings

21. Science Fair Project Ideas Acid Rain Effects on Ocean Life Or local aquatic life or local plants

22. CLEAN AIR ACT Passed 1990 Motor emission standards Factory clean emission standards Aircraft emission standards