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Acid Definitions

Lewis Acid. Brønsted-Lowry. Brønsted-Lowry Definitions A Brønsted-Lowry acid is a proton donor; it donates a hydrogen ion, H + . A Brønsted-Lowry base is a proton acceptor; it accepts a hydrogen ion, H +. Lewis Definitions

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Acid Definitions

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  1. Lewis Acid Brønsted-Lowry Brønsted-Lowry Definitions A Brønsted-Lowry acid is a proton donor; it donates a hydrogen ion, H+. A Brønsted-Lowry base is a proton acceptor; it accepts a hydrogen ion, H+. Lewis Definitions A Lewis acid is a substance than can accept (and share) an electron pair. A Lewis base is a substance than can donate (and share) an electron pair. Acid Definitions Arrhenius acids Arrhenius Acids and Bases Acids release hydrogen ions in water. Bases release hydroxide ions in water. An acid is a substance that produces hydronium ions, H3O+, when dissolved in water.

  2. Acid Definitions Lewis acids The Arrhenius model of acids and bases was broadened by the Brønsted-Lowry model. The Lewis acid-base model is the most general in scope. The Lewis definition of an acid includes any substance that is an electron pair acceptor; a Lewis base is any substance that can act as an electron pair donor. Brønsted-Lowry Arrhenius acids Ralph A. Burns, Fundamentals of Chemistry 1999, page 483

  3. Acid Definitions Lewis acids The Arrhenius model of acids and bases was broadened by the Brønsted-Lowry model. The Lewis acid-base model is the most general in scope. The Lewis definition of an acid includes any substance that is an electron pair acceptor; a Lewis base is any substance that can act as an electron pair donor. Brønsted-Lowry Arrhenius acids Ralph A. Burns, Fundamentals of Chemistry 1999, page 483

  4. Acid – Base Systems

  5. Arrhenius Acid Any substance that releases H+ ions as the only positive ion in the aqueous solution. 1- 1+ + + Cl- H2O H3O+ HCl chloride ion water hydronium ion hydrogen chloride (an Arrhenius acid)

  6. H H – + O O Cl Cl H H H H Definitions • Arrhenius - In aqueous solution… • Acidsform hydronium ions (H3O+) HCl+ H2O  H3O+ + Cl– acid Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

  7. H H – + N O O N H H H H H H H H Definitions • Arrhenius - In aqueous solution… • Bases form hydroxide ions (OH-) NH3+ H2O  NH4+ + OH- base Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

  8. NaOH(s) Na1+(aq) + OH1-(aq) NH3(g) + H2O(l) NH41+(aq) + OH1-(aq) NaOH(aq) + HCl(aq) NaCl(aq) + H2O(l) Arrhenius Bases and Their Properties According to the definition of Arrhenius a: Base - "a substance whose water solution yields... hydroxide ions (OH-) as the only negative ions." YES Are NaOH and NH3 considered to be Arrhenius bases? 1) Bases are electroytes Dissociation equation for NaOH Dissociation equation for NH3 2) Bases cause indicators to turn a characteristic color 3) Bases neutralize acids 4) Water solutions of bases tasted bitter and feel slippery.

  9. NaOH(aq) + HCl(aq) NaCl(aq) + H2O(l) Neutralization Neutralization is a chemical reaction between an acid and a base to produce a salt (an ionic compound) and water. base acid salt water Some neutralization reactions: Na2SO4 + 2 HOH H2SO4(aq) + NaOH(aq) 2 sulfuric acid sodium hydroxide sodium sulfate water Ca(C2H3O2)2 + 2 HOH 2 HC2H3O2(aq) + Ca(OH)2(aq) acetic acid calcium hydroxide calcium acetate water

  10. Neutralization ACID + BASE  SALT + WATER HCl + NaOH  NaCl + H2O strong strong neutral HC2H3O2 + NaOH  NaC2H3O2 + H2O weak strong basic • Salts can be neutral, acidic, or basic. • Neutralization does not mean pH = 7. Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

  11. ACID + BASE  SALT + WATER HCl + NaOH  NaCl + H2O strong strong neutral HC2H3O2 + NaOH  NaC2H3O2 + H2O weak strong basic • Salts can be neutral, acidic, or basic. • Neutralization does not mean pH = 7. Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

  12. NaCl(s) + H2O(l) Na1+(aq) + Cl1-(aq) Salts NaCl Salts - Ionic compounds containing a positive ion other than the hydrogen ion and a negative ion other than the hydroxide ion. i.e., a metal and a non-metal Under what conditions do salts conduct current?

  13. Salt Formation strong base strong acid HCl NaOH salt of a strong base and a strong acid Na Cl NaOH + HCl  NaCl + H2O strong base weak acid HC2H3O2 NaOH salt of a strong base and a weak acid Na C2H3O2 NaOH + HC2H3O2 NaC2H3O2+ H2O Note: that in each case H-OH (water) is formed

  14. Salt Formation weak base strong acid H2SO4 NH3 salt of a weak base and a strong acid (NH4) 2 SO4 H2SO4 NH4OH NH4OH + H2SO4 (NH4)2SO4 + H2O weak base weak acid HC2H3O2 NH3 salt of a weak base and a weak acid NH4 C2H3O2 NH4OH + HC2H3O2 NH4C2H3O2 + H2O Note: that in each case H-OH (water) is also formed

  15. 1+ 1+ H2SO4 NH4OH weak base strong acid H2SO4 NH3 salt of a weak base and a strong acid (NH4) 2 SO4 2 NH4OH + H2SO4 (NH4)2SO4 + 2 HOH water ammonium sulfate sulfuric acid hydroxide ion ammonium ion sulfate ion 1- 1+ 2- 1- 1+ 2 NH4OH + H2SO4 (NH4)2SO4 + 2 H2O NH4+ OH- HOH H2SO4 (NH4)2SO4 OH- NH4+ HOH

  16. Reactions that produce salt acid + base salt + water + H2O (NH4)3PO4 NH4OH H3PO4 + ammonium phosphate ammonium hydroxide phosphoric acid yields and water and H2O Mg(NO3)2 Mg(OH)2 HNO3 magnesium nitrate magnesium hydroxide nitric acid H2O K2CO3 KOH H2CO3 potassium carbonate potassium hydroxide carbonic acid H2O Al(C2H3O2)3 Al(OH)3 HC2H3O2 aluminum acetate aluminum hydroxide acetic acid H2O Ba(ClO4)2 Ba(OH)2 HClO4 barium perchlorate barium hydroxide perchloric acid

  17. Brønsted-Lowry Acids and Bases Acid = any substance that donates a proton. Base = any substance that accepts a proton. 1- 1+ d+ d- + Cl- H2O H3O+ HCl chloride ion (base) hydronium ion (acid)

  18. Brønsted-Lowry Acids and Bases Acid = any substance that donates a proton. Base = any substance that accepts a proton. 1- 1+ d+ d- + Cl- H2O H3O+ HCl chloride ion (base) hydronium ion (acid)

  19. 1- 1+ + OH- NH4+ hydroxide ion ammonium ion Brønsted-Lowry Acids and Bases d- d+ H2O NH3 (acid) (base)

  20. 1- 1+ + OH- NH4+ hydroxide ion ammonium ion Brønsted-Lowry Acids and Bases d- d+ H2O NH3 (acid) (base)

  21. Brønsted-Lowry Acids and Bases 1- 1+ d- d+ + OH- H2O NH4+ NH3 hydroxide ion (acid) ammonium ion (base)

  22. Brønsted-Lowry Acids and Bases 1- 1+ d- d+ + OH- H2O NH4+ NH3 hydroxide ion (acid) ammonium ion (base)

  23. conjugate base conjugate acid Definitions • Brønsted-Lowry • Acidsare proton (H+) donors. • Bases are proton (H+) acceptors. HCl + H2O  Cl– + H3O+ acid base Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

  24. O N H O H O O H Definitions H2O + HNO3 H3O+ + NO3– B A CA CB Acid Base Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

  25. H O H Definitions NH3 + H2O  NH4+ + OH- B A CA CB Acid Base H N H H • Amphoteric - can be an acid or a base. Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

  26. F - H2PO4- H2O HF H3PO4 H3O+ Definitions • Give the conjugate base for each of the following: • Polyprotic - an acid with more than one H+ Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

  27. Br - HSO4- CO32- HBr H2SO4 HCO3- Definitions • Give the conjugate acid for each of the following: Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

  28. Definitions • Lewis • Acidsare electron pair acceptors. • Bases are electron pair donors. Lewis base Lewis acid Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

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