1. The Chemistry of pH 2010

2. What do we know? pH is a scale that runs from 0-14 Acids ( 7) Water is neutral (7) Measures the concentration of H + (and OH-) in solution Logarithmic scale: A pH of 5 is 10x more acidic than a pH of 6

3. The Power of H + What is a hydrogen ion? –A hydrogen atom that gave up its electron –Now just a proton How does it affect living things? How does it affect living things? - Proteins have many H-bonds that determine their shape and so they’re susceptible to pH shifts

6. pH Scale pH 0 = 1 mole/liter pH 7 = 1/10,000,000 moles/liter pH 14 = 1/100,000,000,000,000 moles/liter

7. Molarity (you won’t be tested on this): A mole is equal to 6.022 x 10 23 A 1 molar solution =1 mol/liter It is determined by taking the molecular weight of the molecule and adding that number of grams to 1 liter of water.

8. Acid –A substance that increases the H + concentration of a solution –HCl  H + + Cl - Strong: dissociates completely & irreversibly Weak: do not dissociate completely Base –A substance that reduces the H + concentration of a solution –NaOH  Na + + OH - Strong: dissociates easily, quickly ties up H + Weak: incomplete dissociation, accepts few H +

9. Buffer A substance that minimizes changes in the conc. of H + in a solution Weak acids or bases that combine reversibly –Bind to H + when pH drops –Release H + when pH rises

10. Blood pH Ranges from 7.35-7.45 7.45+ is Alkalosis 7.0-7.35 is Acidosis

11. Carbonic Acid-Bicarbonate Buffering System of the Blood

12. pH of other body fluids Gastric juice HCl (stomach acid) (~2) Urine (5-8) –Basic in bacterial infection –Vegetarian diet Saliva (~6.5)

13. Where is acid produced? Breakdown of P-containing proteins Lactic acid (anaerobic respiration) Fat metabolism CO 2 in blood And HCl in the stomach (but technically not in your body fluids)

14. Lines of defense 1. Chemical buffers –Carbonic Acid-Bicarbonate, proteins in blood, etc. –Respond in a fraction of a second 2. Respiratory center in the brainstem –Control breathing rate (CO 2 a source of acid) –1-3 mins –What will it do if blood is too acidic? 3. Kidneys –Secreting or reabsorbing H + –Slow to respond (1 day or more)