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Acids, Bases, & Salts

Acids, Bases, & Salts. What is an ACID?. 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 . Acids Generate Ions.

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Acids, Bases, & Salts

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  1. Acids, Bases, & Salts

  2. What is an ACID? • pH less than 7 • Neutralizes bases(form salts and water) • Forms H + (H3O+) ions in solution • Corrosive-reacts with most metals • Good conductors of electricity • Taste sour

  3. Acids Generate Ions HNO3 + H2O  H3O+ + NO3

  4. Weak vs. Strong Acids • Weak Acids do not ionize completely: Acetic, Boric, Nitrous, Phosphoric, Sulfurous • Strong Acids ionize completely: Hydrochloric, Nitric; Sulfuric, Hydriodic

  5. Common Acids • HCl- hydrochloric- stomach acid • H2SO4- sulfuric acid - car batteries • HNO3 – nitric acid - explosives • HC2H3O2- acetic acid - vinegar • H2CO3-carbonic acid – sodas • H3PO4- phosphoric acid -flavorings

  6. What is a BASE? • pH greater than 7 • Feels slippery, soapy • Taste bitter, chalky • Are electrolytes • Dissolves fats and oils • Usually forms OH- ions in solution • Neutralizes acids

  7. Weak vs. Strong Bases • Weak Bases: ammonia; potassium carbonate, sodium carbonate • Strong Bases: sodium hydroxide; sodium phosphate; barium hydroxide; calcium hydroxide

  8. Com Common Bases • NaOH- sodium hydroxide (LYE) soaps, drain cleaner • Mg (OH)2 - magnesium hydroxide-antacids • Al(OH)3-aluminum hydroxide-antacids, deodorants • NH4OH-ammonium hydroxide- “ammonia”

  9. Learning Check AB1 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 Timberlake

  10. Solution AB1 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 Timberlake

  11. Learning Check AB2 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 Timberlake

  12. Solution AB2 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, B4. Is an electrolyte _A_ 5. Produces H+ in aqueous solutions LecturePLUS Timberlake

  13. pH Scale • 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. [H+] M A strong acid 100 10-1 10-2 10-3 10-4 10-5 10-6 10-7 10-8 10-9 10-10 10-11 10-12 A strong base 10-13 10-14 SOURCE: http://en.wikipedia.org/wiki/Image:PH_scale.png#file pH • 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+]. The pH scale goes from 0 to 14—because [H+][OH-] = 10-14

  15. pH of Common Substance pH [H1+] [OH1-] pOH 14 1 x 10-14 1 x 10-0 0 13 1 x 10-13 1 x 10-1 1 12 1 x 10-12 1 x 10-2 2 11 1 x 10-11 1 x 10-3 3 10 1 x 10-10 1 x 10-4 4 9 1 x 10-9 1 x 10-5 5 8 1 x 10-8 1 x 10-6 6 6 1 x 10-6 1 x 10-8 8 5 1 x 10-5 1 x 10-9 9 4 1 x 10-4 1 x 10-10 10 3 1 x 10-3 1 x 10-11 11 2 1 x 10-2 1 x 10-12 12 1 1 x 10-1 1 x 10-13 13 0 1 x 100 1 x 10-14 14 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 7 1 x 10-7 1 x 10-7 7 More acidic

  16. Acid – Base Concentrations 10-1 pH = 3 pH = 11 OH- H3O+ pH = 7 10-7 concentration (moles/L) H3O+ OH- OH- H3O+ 10-14 [H3O+]<[OH-] [H3O+]>[OH-] [H3O+]=[OH-] acidic solution neutral solution basic solution Timberlake, Chemistry 7th Edition, page 332

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

  18. Reactions with indicators

  19. pH paper • pH paper changes color to indicate a specific pH value.

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

  21. Situations in which pH is controlled • “Heartburn” • Planting vegetables and flowers • Fish Tanks and Ponds • Blood • Swimming pools

  22. Digestion and pH • 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)

  23. pH in the Digestive System • 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

  24. Digestive system mouth esophagus stomach small intestine large intestine

  25. Acids, Bases, and Salts The End

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