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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 14Acid 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 MOM – Milk of Magnesia – Magnesium hydroxide
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
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)
AcidsReact withCarbonates 2HC2H3O2+Na2CO3 2 NaC2H3O2 + H2O + CO2
Acids Neutralize Bases Neutralization reactions ALWAYS produce a salt and water. HCl + NaOHNaCl + H2O H2SO4 + 2NaOH Na2SO4 + 2H2O 2HNO3 + Mg(OH)2Mg(NO3)2 + 2H2O
Acids Effect Indicators Bluelitmus paper turnsredin contact with an acid.
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
Effects of Acid Rain on Marble(calcium carbonate) George Washington: BEFORE George Washington: AFTER
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)
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!)
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”
Phosphoric Acid • A flavoring agent in sodas • Used in the manufacture of detergents • Used in the manufacture of fertilizers • Not a common laboratory reagent
Acetic Acid • Used in the manufacture of plastics • Used in making pharmaceuticals • Acetic acid is the acid present in vinegar
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)
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
Bases you SHOULD know! Strong BasesWeak Bases Group IA and IIA hydroxides Be(OH)2 NH3
Bases Effect Indicators Red litmus paper turns blue in contact with a base. Phenolphthalein turns pink/purple in a base.
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
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.
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) _______________________________________________________
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
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
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
Stages of ionization ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
Amphoteric • Any substance that can act as an acid or a base. • Ex: Water NH3 + H2O NH4+ + OH- ___________________________________________________________ H2SO4 + H2O H3O+ + HSO4– ___________________________________________________________
Do assignments #2,3,4 Continue with chapter 15 End power point for chapter 14
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.
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
Examples of Bases • Sodium hydroxide (lye), NaOH • Potassium hydroxide, KOH • Magnesium hydroxide, Mg(OH)2 • Calcium hydroxide (lime), Ca(OH)2