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Biological Buffers

Biological Buffers. Buffers. Allow biological fluids to maintain relatively constant pH despite additions of acids or bases. For Example: Blood. Human blood is normally pH 7.4. If you added a strong acid to water it could change from pH 7 to pH 2 very quickly.

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Biological Buffers

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  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 NaOH H2SO4

  8. Acid or Base? • NaOH HCl acid base H2SO4 base acid

  9. Carbonic Acid H2CO3 is an H+ donor (Acid) Bicarbonate Ion HCO3- is an H+ acceptor (Base) Notice the double arrow in the equation above: that means the reaction can go both ways.

  10. Buffer Equilibrium • H2CO3is in equilibrium with HCO3− + H+ • H2CO3 HCO3− + 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 CO2 reacts with water. • This will remove the carbonate ion concentration in the ocean. NOTE CO2 LEVEL INCREASE.

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

  15. 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)

  16. ACID PRECIPITATION

  17. Why is the pH lower in the East?

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

  19. 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

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

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

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