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Chapter 14 Acid and Base Chemistry

Chapter 14 Acid and Base Chemistry. Introduction Do not copy. Acids Milk – Lactic Acid Vinegar – Acetic Acid Carbonated drinks – Phosphoric and Carbonic Acids Citrus fruits – Citrus Acid Apples – Malic Acid Tea – Tannic Acid Bases Lye – sodium hydroxide

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Chapter 14 Acid and Base Chemistry

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  1. Chapter 14Acid and Base Chemistry

  2. Introduction Do not copy Acids Milk – Lactic Acid Vinegar – Acetic Acid Carbonated drinks – Phosphoric and Carbonic Acids Citrus fruits – Citrus Acid Apples – Malic Acid Tea – Tannic Acid Bases Lye – sodium hydroxide MOM – Milk of Magnesia – Magnesium hydroxide

  3. General Properties of Acids • Acids taste sour – never use taste to identify • Acids effect indicators • Blue litmus red • Phenolphthalein  clear • Neutral litmus  red • Acids have a pH lower than 7 • Acids are proton (hydrogen ion, H+) donors • Acids react with active metals, produce H2 • Mg (s) + HCl(aq)  MgCl2(aq) + H2 (g) • Acids react with carbonates • Acids neutralize bases • Neutralization rx. Acid + Base  Water + Salt • Acids ionize – good electrolytes

  4. Acids React with Active Metals Acids react with active metals to form salts and hydrogen gas. Mg + 2HCl  MgCl2 + H2(g) Zn + 2HCl  ZnCl2 + H2(g) Mg + H2SO4 MgSO4 + H2(g)

  5. AcidsReact withCarbonates 2HC2H3O2+Na2CO3 2 NaC2H3O2 + H2O + CO2

  6. Acids Neutralize Bases Neutralization reactions ALWAYS produce a salt and water. HCl + NaOHNaCl + H2O H2SO4 + 2NaOH Na2SO4 + 2H2O 2HNO3 + Mg(OH)2Mg(NO3)2 + 2H2O

  7. Acids Effect Indicators Bluelitmus paper turnsredin contact with an acid.

  8. Acids you SHOULD know: Strong Acids Weak Acids Sulfuric acid, H2SO4 Phosphoric acid, H3PO4 Hydrochloric acid, HCl Acetic acid, HC2H3O2 Nitric acid, HNO3 Hydrobromic acid, HBr

  9. Acids Have a pH less than 7

  10. Effects of Acid Rain on Marble(calcium carbonate) George Washington: BEFORE George Washington: AFTER

  11. Sulfuric Acid • Highest volume production of any chemical in the U.S. • Used in the production of paper • Used in production of fertilizers • Used in petroleum refining Thick clouds of sulfuric acid are a feature of the atmosphere of Venus. (image provided by NASA)

  12. Nitric Acid • Used in the production of fertilizers • Used in the production of explosives • Nitric acid is a volatile acid – its reactive components evaporate easily • Stains proteins (including skin!)

  13. Hydrochloric Acid • Used in the pickling of steel • Used to purify magnesium from sea water • Part of gastric juice, it aids in the digestion of protein • Sold commercially as “Muriatic acid”

  14. Phosphoric Acid • A flavoring agent in sodas • Used in the manufacture of detergents • Used in the manufacture of fertilizers • Not a common laboratory reagent

  15. Acetic Acid • Used in the manufacture of plastics • Used in making pharmaceuticals • Acetic acid is the acid present in vinegar

  16. Acid Nomenclature Rules Naming-Review • Binary acids – two elements Prefix = Hydro – stem – Suffix = ic • Ternary acids or Oxyacids Prefix = Per Suffix = ic (per-ate ion) Suffix = ic (ate ion) Suffix = ous (ite ion) Prefix = Hypo Suffix = ous (hypo-ite ion)

  17. General Properties of Bases • Bases taste bitter – never use taste to identify • Bases effect indicators • Red litmus  blue • Phenolphthalein  pink • Neutral litmus  blue • Bases have a pH higher than 7 • Bases are proton (hydrogen ion, H+) acceptors • Bases feel very slippery • Bases neutralize acids • Neutralization rx. Base + Acid  Water + Salt • Bases dissociate – good electrolytes

  18. Bases you SHOULD know! Strong BasesWeak Bases Group IA and IIA hydroxides Be(OH)2 NH3

  19. Bases Effect Indicators Red litmus paper turns blue in contact with a base. Phenolphthalein turns pink/purple in a base.

  20. Bases have a pH greater than 7

  21. Bases Neutralize Acids Milk of Magnesia contains magnesium hydroxide, Mg(OH)2, which neutralizes stomach acid, HCl. 2 HCl + Mg(OH)2 MgCl2 + 2 H2O

  22. Acid Base Theories • Lewis Theory – used in Organic Chemistry Lewis acids are electron acceptors. Lewis bases are electron donors. • Arrhenius Theory- Svante Arrhenius noticed that aqueous solutions of acids and bases were good conductors. • Arrhenius Theory is very narrow because it requires water and focuses on the products.

  23. Arrhenius Theory Arrhenius Acid = Produces or increases hydrogen ions (H+) in water (attach to water) Ex: HCl + H2O  H3O++ Cl– (aq) ____________________________________ Arrhenius Base = Produces or increases hydroxide ions in water Ex: NaOH + H2O Na + (aq) + OH -(aq) _______________________________________________________

  24. Some materials act as acids and bases when not in water and this gives rise to other theories • Bronsted-Lowry Theory – important for aqueous solutions and inorganic chemistry. • Bronsted –Lowry Acid = Proton (H+) Donor • Bronsted-Lowry Base = Proton (H+) Acceptor • Proton = H+ ion

  25. Bronsted-Lowry examples HCl + H2O  H3O + + Cl– Acid Base conjugate acid conjugate base The stronger the acid, the weaker the conjugate and vise-versa HCl + NH3  NH4+ + Cl– Acid Base conjugate acid conjugate base

  26. Protic Terms Monoprotic acids Diprotic acids Triprotic acids H3PO4 HCl H2SO4 HC2H3O2 H2CO3 HNO3 Mono- candonate 1 hydrogen Di – can donate 2 hydrogen Tri- candonate 3 hydrogen Polyprotic – includes Di- and Tri-protic acids

  27. Stages of ionization ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

  28. Amphoteric • Any substance that can act as an acid or a base. • Ex: Water NH3 + H2O  NH4+ + OH- ___________________________________________________________ H2SO4 + H2O  H3O+ + HSO4– ___________________________________________________________

  29. Do assignments #2,3,4 Continue with chapter 15 End power point for chapter 14

  30. Strong Acid Dissociation

  31. Weak Acid Dissociation

  32. Organic Acids Organic acids all contain the “carboxyl” group, sometimes several of them. The carboxyl group is a poor proton donor, so ALL organic acids are weak acids.

  33. Examples of Organic Acids • Citric acid in citrus fruit • Malic acid in sour apples • Deoxyribonucleic acid, DNA • Amino acids, the building blocks of protein • Lactic acid in sour milk and sore muscles • Butyric acid in rancid butter

  34. Examples of Bases • Sodium hydroxide (lye), NaOH • Potassium hydroxide, KOH • Magnesium hydroxide, Mg(OH)2 • Calcium hydroxide (lime), Ca(OH)2

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