pH less than 7 Neutralizes bases(form salts and water) Forms H + (H 3 O + ) ions in solution Corrosive-reacts with most metals Good conductors of electricity Taste sour

HNO 3 + H 2 O  H 3 O + + NO 3

 Weak Acids do not ionize completely: Acetic, Boric, Nitrous, Phosphoric, Sulfurous  Strong Acids ionize completely: Hydrochloric, Nitric; Sulfuric, Hydriodic

HCl- hydrochloric- stomach acid H 2 SO 4 - sulfuric acid - car batteries HNO 3 – nitric acid - explosives HC 2 H 3 O 2 - acetic acid - vinegar H 2 CO 3 -carbonic acid – sodas H 3 PO 4 - phosphoric acid -flavorings

 pH greater than 7  Feels slippery, soapy  Taste bitter, chalky  Are electrolytes  Dissolves fats and oils  Usually forms OH - ions in solution  Neutralizes acids

 Weak Bases: ammonia; potassium carbonate, sodium carbonate  Strong Bases: sodium hydroxide; sodium phosphate; barium hydroxide; calcium hydroxide

 NaOH- sodium hydroxide (LYE) soaps, drain cleaner  Mg (OH) 2 - magnesium hydroxide-antacids  Al(OH) 3 -aluminum hydroxide-antacids, deodorants  NH 4 OH-ammonium hydroxide- “ammonia”

LecturePLUS Timberlake9 Describe the solution in each of the following as: 1) acid 2) base or 3)neutral. A. ___soda B. ___soap C. ___coffee D. ___ wine E. ___ water F. ___ grapefruit

LecturePLUS Timberlake10 Describe each solution as: 1) acid 2) base or 3) neutral. A. _1_ soda B. _2_ soap C. _1_ coffee D. _1_ wine E. _3_ water F. _1_ grapefruit

LecturePLUS Timberlake11 Identify each as characteristic of an A) acid or B) base ____ 1. Sour taste ____ 2. Produces OH - in aqueous solutions ____ 3. Chalky taste ____ 4. Is an electrolyte ____ 5. Produces H + in aqueous solutions

LecturePLUS Timberlake12 Identify each as a characteristic of an A) acid or B) base _A_ 1. Sour taste _B_ 2. Produces OH - in aqueous solutions _B_ 3. Chalky taste A, B 4. Is an electrolyte _A_ 5. Produces H + in aqueous solutions

 We use this scale to measure the strength of an acid or base.  pH is defined as the –log[H+]  pH can use the concentration of hydronium ions or hydrogen ions.

14 Most living cells have a very narrow range of tolerance for pH, i.e. [H + ]. The [H + ] concentration will be important (either explicitly or implicitly) for many other topics in biology. [H + ] is controlled in all biological organisms, and in virtually all biochemical experiments. Each pH unit represents a factor of 10 difference in [H + ]. [H + ][OH - ] = The pH scale goes from 0 to 14—because [H + ][OH - ] = pH [H + ] M A strong acid A strong base SOURCE:

14 1 x x x x x x x x x x x x x x x x x x x x x x x x x x x x NaOH, 0.1 M Household bleach Household ammonia Lime water Milk of magnesia Borax Baking soda Egg white, seawater Human blood, tears Milk Saliva Rain Black coffee Banana Tomatoes Wine Cola, vinegar Lemon juice Gastric juice More basic More acidic pH [H 1+ ] [OH 1- ] pOH 7 1 x x

pH = 3 pH = 7 pH = 11 OH - H3O+H3O+ H3O+H3O+ H3O+H3O+ [H 3 O + ] = [OH - ] [H 3 O + ] > [OH - ] [H 3 O + ] < [OH - ] acidic solution neutral solution basic solution concentration (moles/L) Timberlake, Chemistry 7 th Edition, page 332

pH = -log [H + ] Kelter, Carr, Scott, Chemistry A World of Choices 1999, page 285

Reactions with indicators IndicatorAcid color Neutral color Base color PhenolphthaleinColorlessFaint pinkDark pink Bromthymol blue YellowGreenBlue LitmusRed-----Blue

 pH paper changes color to indicate a specific pH value.

 A buffer is a solution that resists changes in pH when small amounts of acids and bases are added.

 “Heartburn”  Planting vegetables and flowers  Fish Tanks and Ponds  Blood  Swimming pools

 Digestion-process by which foods are broken down into simpler substances.  Mechanical digestion-physical process in which food is torn apart (mouth)  Chemical digestion- chemical reactions in which large molecules are broken down into smaller molecules. (stomach and small intestines)

 Mouth-pH around 7. Saliva contains amylase, an enzyme which begins to break carbohydrates into sugars.  Stomach- pH around 2. Proteins are broken down into amino acids by the enzyme pepsin.  Small intestine-pH around 8. Most digestion ends. Small molecules move to bloodstream toward cells that use them

mouth esophagus stomach small intestine large intestine Digestive system