1 / 28

Acid-Base theories

Acid-Base theories. An Introduction. Properties of acids and bases. Acids: Taste sour or tart React with some metals to produce H 2 ( g ) Turn litmus paper red Can be strong (HCl) or weak (CH 3 COOH). Properties of acids and bases. Common Acids: HCl: hydrochloric acid

kylar
Télécharger la présentation

Acid-Base theories

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. Acid-Base theories • An Introduction

  2. Properties of acids and bases • Acids: • Taste sour or tart • React with some metals to produce H2(g) • Turn litmus paper red • Can be strong (HCl) or weak (CH3COOH)

  3. Properties of acids and bases • Common Acids: • HCl: hydrochloric acid • HNO3: nitric acid • H2SO4: sulfuric acid • H3PO4: phosphoric acid • CH3COOH: acetic (ethanoic) acid • H2CO3: carbonic acid

  4. Properties of acids and bases • Bases: • Taste bitter • Feel slippery • Turn litmus paper blue • Can be strong (NaOH) or weak (NH3)

  5. Properties of acids and bases • Common Bases: • KOH: potassium hydroxide • NaOH: sodium hydroxide • Ca(OH)2: calcium hydroxide • Mg(OH)2: magnesium hydroxide

  6. Theories • Acid-Base theories try to explain the actions of acids and bases. • Acids and bases play such a very important role in general and biochemistry that we need a good theory to help us understand the reactions. • In addition, with a good theory, we should be able to predict the products of unknown but related reactions.

  7. Theories • All theories deal with strong and weak acids and bases. • Strong acids and bases are fully dissociated in solution. • HCl(g) → H+(aq) + Cl-(aq) • NaOH(s) → Na+(aq) + OH-(aq) • The reactions go to completion. • There are no reactants present in the solution.

  8. Theories • Strong acids (these are all of them): • HCl hydrochloric acid • HBr hydrobromic acid • HI hydroiodic acid • HNO3 nitric acid • HClO3 chloric acid • H2SO4 sulfuric acid

  9. Theories • Strong bases: • all metal hydroxides, such as • NaOH sodium hydroxide • KOH potassium hydroxide • Ca(OH)2 calcium hydroxide

  10. Theories • Weak acids and bases are only partially dissociated. • There is an equilibrium when the rate of product formation equals the rate of reactant formation. • CH3COOH(aq) + H2O(l) ⇌ H3O+(aq) + CH3COO-(aq) • NH3(aq) + H2O(l) ⇌ NH4+(aq) + OH-(aq) • Both reactants and products remain in solution.

  11. Theories • Weak acids: • any acid not a strong acid, such as • H3PO4 phosphoric acid • CH3COOH acetic acid • HF hydrofluoric acid

  12. Theories • Weak bases: • any base that is not a metal hydroxide, such as • NH3 ammonia • CH3NH2 methylamine • CH3CH2NH2 ethylamine • and other nitrogen containing organic compounds

  13. Arrhenius acids and bases • Arrhenius acids are • H+ containing compounds • increase the H+ concentration in water • Typical reactions: • H-Cl(g) → H+(aq) + Cl-(aq) • H-Cl(g) + H2O(l)→ H3O+(aq) + Cl-(aq) hydronium ion

  14. Arrhenius acids and bases • Arrhenius bases are • OH- containing compounds • increase the OH- concentration in water • Typical Reactions: • NaOH(s) → Na+(aq) + OH-(aq) • KOH(s) → K+(aq) + OH-(aq)

  15. Brønsted-Lowry acids and bases • Brønsted-Lowry acids are • H+ donors • HCl(g) + H2O(l) → Cl-(aq) + H3O+(aq) • Brønsted-Lowry bases are • H+ acceptors • NH3(g) + H2O(l) → NH4+(aq) + OH-(aq)

  16. Brønsted-Lowry acids and bases • Conjugate acids and bases: • HCl(g) + H2O(l) → Cl-(aq) + H3O+(aq) • In this reaction • HCl is the H+ donor (acid) • H2O is the H+ acceptor (base) (acid) (base)

  17. Brønsted-Lowry acids and bases • Conjugate acids and bases: • HCl(g) + H2O(l) → Cl-(aq) + H3O+(aq) • In the reverse reaction (acid) (base) (base) (acid) • H3O+ is the H+ donor (acid) • Cl- is the H+ acceptor (base)

  18. Brønsted-Lowry acids and bases • Conjugate acids and bases: • HCl(g) + H2O(l) → Cl-(aq) + H3O+(aq) (acid) (base) (base) (acid) • HCl is an acid • Cl- is a base • HCl and Cl- are conjugate acid and base.

  19. Brønsted-Lowry acids and bases • Conjugate acids and bases: • HCl(g) + H2O(l) → Cl-(aq) + H3O+(aq) (acid) (base) (base) (acid) • H3O+ is an acid • H2O is a base • H3O+ and H2O are conjugate acid and base.

  20. Brønsted-Lowry acids and bases • Conjugate acids and bases: • NH3(g) + H2O(l) → NH4+(aq) + OH-(aq) • In this reaction • H2O is the H+ donor (acid) • NH3 is the H+ acceptor (base) (base) (acid)

  21. Brønsted-Lowry acids and bases • Conjugate acids and bases: • NH3(g) + H2O(l) → NH4+(aq) + OH-(aq) • In the reverse reaction (base) (acid) (acid) (base) • NH4+ is the H+ donor (acid) • OH- is the H+ acceptor (base)

  22. Brønsted-Lowry acids and bases • Conjugate acids and bases: • NH3(g) + H2O(l) → NH4+(aq) + OH-(aq) (base) (acid) (acid) (base) • NH3 is a base • NH4+ is an acid • NH3 and NH4+ are conjugate acid and base.

  23. Brønsted-Lowry acids and bases • Conjugate acids and bases: • NH3(g) + H2O(l) → NH4+(aq) + OH-(aq) (base) (acid) (acid) (base) • H2O is an acid • OH- is a base • H2O and OH- are conjugate acid and base.

  24. Brønsted-Lowry acids and bases • Notice that in the reaction • HCl(g) + H2O(l) → Cl-(aq) + H3O+(aq) • H2O acts as a base • and in the reaction • NH3(g) + H2O(l) → NH4+(aq) + OH-(aq) • H2O acts as an acid

  25. Brønsted-Lowry acids and bases • The behavior of water to act as a base or as an acid is called amphoterism. • Water is amphoteric. • Other species can also be amphoteric: • HSO4- (hydrogen sulfate ion) • HCO3- (hydrogen carbonate ion) • H2PO4- (dihydrogen phosphate ion)

  26. . . • : • . . Lewis acids and bases • Lewis acid: • e- pair acceptor • H+ (the H is e- poor) • Lewis base: • e- pair donor • O−H- (the O is e- rich)

  27. Lewis acids and bases • Lewis acid/base reactions: • H+(aq) + H2O(l) → H3O+(aq) • H3O+ is called a Lewis acid/base adduct. • NH3(g) + H+(aq) → NH4+(aq) • Cl3B(g) + :NH3(g) → Cl3B−NH3(s) • Cl3B−NH3 is called a Lewis acid/base adduct.

  28. acids/bases theories

More Related