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Acid and Base Definitions

Acid and Base Definitions. SAVE PAPER AND INK!!! When you print out the notes on PowerPoint, print "Handouts" instead of "Slides" in the print setup. Also, turn off the backgrounds (Tools>Options>Print>UNcheck "Background Printing")!. Acid and Bases. Acid and Bases. Acid and Bases. Acids.

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Acid and Base Definitions

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  1. Acid and Base Definitions SAVE PAPER AND INK!!! When you print out the notes on PowerPoint, print "Handouts" instead of "Slides" in the print setup. Also, turn off the backgrounds (Tools>Options>Print>UNcheck "Background Printing")!

  2. Acid and Bases

  3. Acid and Bases

  4. Acid and Bases

  5. Acids Have a sour taste. Vinegar is a solution of acetic acid. Citrus fruits contain citric acid. React with certain metals to produce hydrogen gas. React with carbonates and bicarbonates to produce carbon dioxide gas Bases Have a bitter taste. Feel slippery. Many soaps contain bases.

  6. Some Properties of Acids • Produce H+ (as H3O+) ions in water (the hydronium ion is a hydrogen ion attached to a water molecule) • Taste sour • Corrode metals • Electrolytes • React with bases to form a salt and water • pH is less than 7 • Turns blue litmus paper to red “Blue to Red A-CID”

  7. Acid Nomenclature Review No Oxygen w/Oxygen An easy way to remember which goes with which… “In the cafeteria, you ATEsomethingICky”

  8. Acid Nomenclature Flowchart

  9. Acid Nomenclature Review • HBr(aq) • H2CO3 • H2SO3 hydrobromicacid  carbonicacid  sulfurousacid

  10. Some Properties of Bases • Produce OH- ions in water • Taste bitter, chalky • Are electrolytes • Feel soapy, slippery • React with acids to form salts and water • pH greater than 7 • Turns red litmus paper to blue “BasicBlue”

  11. Some Common Bases NaOH sodium hydroxide lye KOH potassium hydroxide liquid soap Ba(OH)2 barium hydroxide stabilizer for plastics Mg(OH)2 magnesium hydroxide “MOM” Milk of magnesia Al(OH)3 aluminum hydroxide Maalox (antacid)

  12. Acid/Base definitions • Definition #1: Arrhenius (traditional) Acids – produce H+ ions (or hydronium ions H3O+) in water Bases – produce OH- ions in water (problem: some bases don’t have hydroxide ions!)

  13. Arrhenius acid is a substance that produces H+ (H3O+) in water Arrhenius base is a substance that produces OH- in water

  14. Acid/Base Definitions • Definition #2: Brønsted – Lowry Acids – proton donor Bases – proton acceptor A “proton” is really just a hydrogen atom that has lost it’s electron!

  15. A Brønsted-Lowryacidis a proton donor A Brønsted-Lowrybaseis a proton acceptor conjugatebase conjugateacid base acid

  16. ACID-BASE THEORIES The Brønsted definition means NH3 is aBASEin water — and water is itself anACID

  17. Amphoteric Substances • A substance that is amphoteric can act as either an acid or a base. • In the previous slide, water acted as an acid. • In the following example, water acts as a base. HCl (g) + H2O (l)  H3O+ (aq) + Cl- (aq) acid base conj. acid conj. base

  18. Conjugate Pairs

  19. Acid-Base Behavior • Consider a compound having the formula HOX. • If X is highly electronegative, it will have a strong attraction for the electrons shared with O. • The O, will in turn, pull strongly on the electrons held shared with H. • This H will then be easily lost = acid • If X has a low electronegativity, the oxygen will pull the electrons away from X. • The hydrogen will remain joined to the oxygen. • Since the O and H can easily remain together, it is likely that OH- will be formed = base • Nonmetals tend to have high EN = acids • Metals tend to have low EN = bases

  20. Acids & Base Definitions Definition #3 – Lewis Lewis acid - a substance that accepts an electron pair Lewis base - a substance that donates an electron pair

  21. Lewis Acids & Bases Formation ofhydronium ion is also an excellent example. • Electron pair of the new O-H bond originates on the Lewis base.

  22. Lewis Acid/Base Reaction

  23. Lewis Acid-Base Interactions in Biology • The heme group in hemoglobin can interact with O2 and CO. • The Fe ion in hemoglobin is a Lewis acid • O2 and CO can act as Lewis bases Heme group

  24. HOMEWORK • Identify the acid, base, conjugate acid, and conjugate base in the following reactions (using the Bronsted-Lowry definition): • HNO3 (aq) + NaOH (aq)  H2O (l) + NaNO3 (aq) • NaHCO3 (aq) + HCl (aq)  NaCl (aq) + H2CO3 (aq) • What is the conjugate base of each of the following acids? • H2SO3 c) NH3 • H2CO3 d) HF 3) Classify each of the following substances as either a Lewis acid or a Lewis base: • Cl- c) Na+ • CO32- d) Br-

  25. MORE HOMEWORK • Describe the differences in the three acid-base definitions of this PowerPoint. • What are conjugate acids and bases? • Name the following substances: • HCl (aq) b) H2SO4 c) KOH • What kind of element would you expect to find in position X of the compound HOX if the compound is determined to be amphoteric?

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