1. pH Notes Learning target: #8 – pH scale #9 - Acids, Bases and Buffers

2. Solution A solution is a mixture in which one or more substances are uniformly distributed in another Solute = substance dissolved in the solution Solvent = substance in which the solute is dissolved

3. Concentration = measure of the amount of solute dissolved in a fixed amount of solution Ex: 4% salt solution = 4 g salt dissolved in enough water to make 100 mL Saturated solution one in which no more solute can dissolve Aqueous solution = one in which water is the solvent (fresh or sea water, intercellular fluid)

4. Dissociation is the breaking apart of molecules into two ions. Small amounts of water naturally dissociates into ions in a solution. H 2 0H+ + OH-

5. pH scale = compares relative concentrations of hydrogen ions (H+) to hydroxide ions (OH-) in a solution HISTORY: Discovered in 1909 by a Danish scientist: Sorenson Shows the potential for Hydrogen

8. pH scale: ranges from 1-14 Less than 7 = acid (H+ > OH-) “AH” At 7 = neutral (H+ = OH-) Greater than 7 = base (H+ < OH-) “BOH”

9. ACIDS When dissolved in water they produce H2O HCl H+ + Cl- Taste sourStings in open wounds/eyes Ex: boric acid is used to wash eyes acetic acid is used to make vinegar citric acid is found in lemons, limes, oranges HCl is used to clean brick and tile, make sugar and glue, found in stomach

10. BASES When dissolved in water they produce H20 NaOH Na+ + OH- Feel slippery (like soap) tastes bitter Doesn’t sting in open wounds/eyes Ex: ammonia: cleaner used to make soap, rayon, paper, plaster **Both Acids and Bases can be harmful and dangerous

11. Balance and control of pH is very important in living things.

12. What does the pH scale mean? Measured in power of 10, like the metrics pH of 4 is 10x more acidic than a pH of 5 pH of 5 is 100x more acidic than a pH of 7

13. BUFFER A buffer is a substance that stabilizes small amounts of acid or base. Resists change to pH. Ex: Protein buffers in cells neutralize acids Ionic buffers in blood, lymph and extra and intracellular fluids also neutralize acids which are removed through the urine.

14. Use of Buffers: Blood pH is 7.3 normally Ex: If the pH of blood goes below 7.0 or above 7.8 death can occur Urine’s pH is diet dependent

15. What you eat influences your pH Acid forming foods: meat, fish, poultry, eggs, peanuts, cheddar cheese Alkalinic (basic) forming foods: most fruits and vegetables Neutral foods: brown rice, corn, soybean, almond, honey, dried beans and peas Doctors check urine pH to look for acidosis or alkalosis… can cause: kidney stones, hypertension,osteoporosis