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Acid, Bases, and Salts

Acid, Bases, and Salts. Chemistry—Part 1. I. Acids. H   is a nonmetal or polyatomic ion  could be Cl - , SO 4 2- , etc. Ex: HCl, HF, H 2 SO 4 , HClO 4 , H 3 PO 4. Acids (con’t). dissociate to form H + ions (protons) Hydrogen Atom Hydrogen Ion (proton). e -. +.

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Acid, Bases, and Salts

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  1. Acid, Bases, and Salts Chemistry—Part 1

  2. I. Acids H  is a nonmetal or polyatomic ion  could be Cl- , SO42-, etc. Ex: HCl, HF, H2SO4 , HClO4, H3PO4

  3. Acids (con’t) dissociate to form H+ ions (protons) Hydrogen AtomHydrogen Ion(proton) e- +

  4. A. Ionization in Water H3O+ + Cl- HCl + H2O  H+ combines with H2O to form H3O+ Hydronium Ion H+(proton) is attracted to lone e- pairs in H2O + -

  5. Try This: H2SO4 + H2O  H3PO4 + H2O  2 2 H3O+ + SO42- + SO42- SO42- + 3 3 H3O+ + PO43-

  6. B. Examples • Soda pop – H2CO3, H3PO4 • Vinegar (acetic acid) – HC2H3O2 • Lemons – citric acid • Stomach acid – HCl • Battery acid – H2SO4 • Sour Patch Kids – Tartaric Acid

  7. C. Properties • taste sour • conduct electricity • turn litmus red • react with some metals to produce H2 (g) Remember, Zn + 2HCl  ZnCl2 + H2(g) • corrosive • All form H+ ions in solution

  8. II. Bases contain OH- (hydroxide ions) Ex: Ca(OH)2, LiOH, NH4OH, NaOH Also calledalkaline (alkali) Alkali Flats Bonneville Salt Flats, Utah

  9. A. Ionization In Water H2O NaOH Na+ + OH- NH4OH Ca(OH)2 H2O NH4+ + OH- H2O Ca2+ + 2 OH-

  10. B. Examples • Drano – NaOH • Oven cleaner – KOH • Tums – Ca(OH)2 • Glass cleaner – NH4OH

  11. C. Properties • Taste bitter (Baking Soda) • Conduct electricity • Turn litmus blue • Feel slippery (hard to wash off of skin) • Caustic (dissolves protein, ie. YOU) • Form OH- ions

  12. III. Reactions of Acids and Bases Neutralization: Acid + Base  Salt + Water HBr + NaOH  Type of reaction? NaBr + H2O DOUBLE DISPLACEMENT!

  13. Try This: HF + LiOH  H2SO4 + KOH  HOH + LiF (H2O) H2O + K2SO4 2 2

  14. Antacids Neutralize stomach acid Ex: Tums HCl + Ca(OH)2  Milk of Magnesia (demo) HCl + Mg(OH)2  2 H2O + CaCl2 2 H2O + MgCl2 2 2

  15. IV. Electrolyte Solutions Substances whose water solutions conduct electricity NaCl (c) vs. NaCl (aq) Sucrose (c) vs. Sucrose (aq) H2O (distilled) vs. H2O (tap) There must be ions present to conduct

  16. Strong & Weak Electrolytes NaCl (s) HF (s) HF F+ Na+ Cl- HF HF Na+ H+ Cl- Na+ + Cl- only ions are present H+ + F- mostly HF present; only some ions STRONG ELECTROLYTES Ionize 100% NaCl  WEAK ELECTROLYTES Only partially ionize HF 

  17. Conductivity Demo NH4OH + HC2H3O2 H2O + NH4C2H3O2 Weak Base Weak Acid Salt

  18. Practice H? ?OH HBr LiOH H2CO3 KOH H2SO4 NH4OH

  19. Lab 49 Pre - Lab NaCl  FeCl3  C6H12O6  Na+ (aq) + Cl- (aq) Fe3+ (aq) + 3 Cl- (aq) C6H12O6 (aq)

  20. V. Naming Acids, Bases & Salts Acid Names 1. Binary Acids contain only TWO elements ex: HCl Hydrochloric Acid Hydro-stem-ic Acid Try: HBr HF H2S Hydrobromic Acid Hydrofluoric Acid Hydrosulfuric Acid

  21. Ternary Acids contain THREE elements (usually) contain H and a polyatomic ion ate icite  ous ex: H2CO3 carbonate carbonic Carbonic Acid

  22. Try These HNO2 nitrite nitrous Nitrous Acid HNO3 nitrate nitric Nitric Acid H2SO3 sulfite sulfurous Sulfurous Acid H2SO4 sulfate sulfuric Sulfuric Acid

  23. Base Names (IUPAC Nomenclature) Combine names of ions NaOH Sodium Hydroxide Ca(OH)2 Calcium Hydroxide

  24. Salt Names Combine names of ions NaBr Sodium Bromide K2SO4 Potassium Sulfate Cu(NO3)2 Copper (II) Nitrate

  25. VI. Salts Salts are ionic and crystalline

  26. A. Dissociation in Water Salt Cation + Anion LiCl Na2SO4 H2O H2O Li+ + Cl- H2O 2 Na+ + SO42-

  27. B. Cation and Anion Cation: Positive (+) charge The ___________ contributes the cation (acid/base?) Anion: Negative (-) charge The ___________ contributes the anion (acid/base?)

  28. C. Examples Na+ Cl- Na+ HCO3- K+ SO42-

  29. Parent Acid / Parent Base Parent Acid: The acid that contributes the ANION to the salt Parent Base: The base that contributes the CATION to the salt

  30. VIII. Strong Acids and Bases STRONG ACIDS—DISSOCIATE 100 % HCl HNO3 H2SO4 STRONG BASES—DISSOCIATE 100% All Alkali Metals (IA) form strong bases

  31. VIII. Weak Acids and Bases WEAK ACIDS—DO NOT DISSOCIATE 100 % WEAK BASES—DO NOT DISSOCIATE 100% How would a weak acid conduct electricity compared to a strong acid?

  32. IX. Polyprotic Acids Acids with more than one proton (H+) • Examples H2SO4 H3AsO4 H3PO4 H2CO3 H2S

  33. B. Step – By – Step Ionization Acids lose one proton at a time 1st H3PO4 2nd H2PO4-  3rd HPO4-2  H3PO4  3H+ + PO43- H+ + H2PO4- H+ + HPO4-2 H+ + PO4-3 H3PO4 + H2O  3 3 H3O+ + PO43-

  34. Questions 1. Which of the following are polyprotic acids? a) HCl d) HC2H3O2 b) NH3 e) H3PO4 c) H2SO4 f) HNO3 2. Which acid is harder to ionize: H3PO4 or HPO4-2? Why? The -2 charge attracts protons (H+) 3. Which acid is stronger: H2SO4 or HSO4-? Why? easier to lose protons (H+)

  35. Lab 50 Answers

  36. Water as an acid and a base amphoteric: water behaves as an acid & base H2O + H2O  H3O+ + OH- acidbaseconjconj acidbase

  37. X. Anhydrides Without water Acidic Anhydrides— non-metallic oxides that combine with H2O to form an acid SO2 + H2O  H2SO3 CO2 + H2O  H2CO3 Acid Anhydrides

  38. Basic Anhydrides— metal oxides that combine with H2O to form a base CaO + H2O  Ca(OH)2 Na2O + H2O  2 NaOH Basic Anhydrides

  39. Try These: Acidic or Basic Anhydride? K2O Basic Anhydride NO2 Acidic Anhydride

  40. http://www.epa.gov/maia/images/acid.jpg

  41. Acid, Bases, and Salts Chemistry—Part 2

  42. I. Molarity Example: 6 KOH 0.1 H2SO4 2 NaCl A measure of concentration M M M

  43. Concentration 6 M 1 M

  44. Examples 3 M HNO3 = 20 moles in 5 L = ? M

  45. Try This! If 80 grams of NaOH (MW=40) is dissolved in 2 L, find the molarity. 6 moles of HBr in 250 ml. Molarity?

  46. Now Try This One! How many moles of HCl are in 500 ml of a 3 M solution?

  47. II. Titration Using a solution of to determine the concentration of another solution. A neutralization reaction Acid + Base  known concentration Salt + Water

  48. End Point The point at which neutralization is complete moles H+ = moles OH- use (like phenolphthalein) to determine the end point acid-base indicators

  49. Acidic—before neutralization Neutral— ”End Point” Basic— “overshot endpoint”

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