1 / 16

Theories of Acids and Bases

Theories of Acids and Bases. Arrhenius Acid. Substance that contains hydrogen & ionizes to produce H + as the only positive ion in aqueous solution. HCl(g)  H + (aq) + Cl - (aq) HNO 3  H + (aq) + NO 3 - (aq). Arrhenius Base.

camilleg
Download Presentation

Theories of Acids and Bases

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Theories of Acids and Bases

  2. Arrhenius Acid • Substance that contains hydrogen & ionizes to produce H+ as the only positive ion in aqueous solution. • HCl(g)  H+(aq) + Cl-(aq) • HNO3  H+(aq) + NO3-(aq)

  3. Arrhenius Base • A substance that contains a hydroxide group & ionizes to produce OH- as the only negative ion in aqueous solution. • NaOH(s)  Na+(aq) + OH-(aq)

  4. Arrhenius Salt • Electrolytes where H+ is not the only positive ion and OH- is not the only negative ion in aq. solution. • Ex: NaCl, CaBr2,KNO3, NH4I

  5. Salts in Water • NaCl(s)  Na+(aq) + Cl-(aq) • CaBr2(s)  Ca+2(aq) + 2Br-(aq) • KNO3(s)  K+(aq) + NO3-(aq) • NH4I(s)  NH4+(aq) + I-(aq) Memory Jogger

  6. Arrhenius Model has limitations • Don’t always use H2O as the solvent. • Arrhenius model only applies when H2O is the solvent. • Doesn’t explain all cases: • NH3 doesn’t contain OH- but it produces OH-.

  7. Alternate Theory: Bronsted-Lowry • Acid = a proton donor • All Arrhenius acids are Bronsted-Lowry Acids. • HX(g) + H2O(l)  H3O+ + X- • H+ forms a molecule-ion bond with the water molecule H3O+, named hydronium ion.

  8. Bronsted-Lowry Acids • HCl + H2O  H3O+ + Cl- • HNO3 + H2O  H3O+ + NO3- • H2SO4 + H2O  H3O+ + HSO4- • HSO4- + H2O  H3O+ + SO4-2

  9. Bronsted-Lowry Base • Base = proton acceptor. • OH- is a base. H+ + OH- H2O • Not restricted to aqueous solution. • NH3 + H2O  NH4+ + OH- • NH3 is a base!

  10. Amphoteric • Substance that can act as both an acid & a base • Water is amphoteric • HX(g) + H2O(l)  H3O+ + X- } H20 = base • NH3 + H2O  NH4+ + OH- } H2O = acid

  11. Water is amphoteric!

  12. Conjugate Acid / Conjugate Base HX + H2O  H3O+ + X- Acid Base Conjugate Acid Conjugate Base Conjugate Acid & Conjugate Base always on product side. Conjugate Acid = species that got the H+ Conjugate Base = species that lost the H+

  13. Bronsted-Lowry Acids & Bases

  14. Identify A., B., C.A., & C.B. • NH3 + H2O  NH4+ + OH- • HCl + H2O  H3O+ + Cl- • HSO4- + H2O  SO4-2 + H3O+ • NH3 + H2S  NH4+ + HS- Acid C. Acid C. Base Base C. Base Base C. Acid Acid Base C. Base C. Acid Acid Base Acid C. Acid C. Base

  15. Lewis Definition • Lewis acid-base theory focuses on the exchange of electron pairs rather than protons to classify as acid or base. • Based on bonding and structure • Includes substances that do NOT contain hydrogen ions. • NH3 + H2O  NH4+ + OH-

  16. Lewis Acids & Bases • A Lewis acid is an atom, ion, or molecule that is an electron-pair acceptor. • Associate: • Bronsted-Lowry acid with: proton donor • Bronsted-Lowry base with: proton acceptor • Lewis acid with: electron pair acceptor • Lewis base with: electron pair donor

More Related