1 / 100

Chapter 15

A.P. Chemistry. Chapter 15. Acids and Bases. General Stuff. Taste Litmus test. General Stuff. Phenolphthalein test Ppth with OH - Remember how to titrate?. General Stuff. pH scale based on an equilibrium system H 2 O <===> H + + OH - K w = 1x10 -14 at 25°C

nellis
Télécharger la présentation

Chapter 15

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. A.P. Chemistry Chapter 15 Acids and Bases

  2. General Stuff • Taste • Litmus test

  3. General Stuff • Phenolphthalein test • Ppth with OH- • Remember how to titrate?

  4. General Stuff • pH scale • based on an equilibrium system • H2O <===> H+ + OH- • Kw = 1x10-14 at 25°C • pH scale is temperature dependent

  5. Acid Base Concepts H2O <===> H+ + OH- H2O + H2O <===> H3O+ + OH- • H+ and H3O+ are synonymous.

  6. Acid Base Definitions • Arrhenius: • Acids contain hydrogen and make H+ or (H3O+) in solution. • Bases contain hydroxide ions and make OH- in solution.

  7. Acid Base Definitions • Strong Acids are Arrhenius acids Substances that ions in solution are electrolytic

  8. Arrhenius Acids • HBr ----> H+ + Br- • HCl ----> H+ + Cl- • HI ----> H+ + I- • H2SO4 ----> 2H+ + SO4 2- • HClO4 ----> H+ + ClO4- • HNO3 ----> H+ + NO3-

  9. Acid Base Definitions • Strong bases are Arrhenius bases. Ammonia is a weak base.

  10. Arrhenius Bases • LiOH ------> Li+ + OH- • NaOH ------> Na+ + OH- • KOH ------> K+ + OH- • Ca(OH)2 ------> Ca2+ + 2OH- • Sr(OH)2 ------> Sr2+ + 2OH- • Ba(OH)2 ------> Ba2+ + 2OH-

  11. Acid Base Definitions • Bronsted-Lowry: • Acids are proton (H+) donors. • Bases are proton acceptors. Johannes Bronsted, Danish Chemist

  12. Acid Base Definitions • Bronsted Lowry acids and bases exist as conjugate pairs.

  13. Bronsted Lowry Examples • water + acetate ion • H2O + C2H3O2- <--->OH- + HC2H3O2 • hydrochloric acid + ammonia • HCl + NH3 <-----> NH4+ + Cl- • bicarbonate + hydrofluoric acid • HCO3- + HF <-----> H2CO3 + F-

  14. LEWIS Acids and Bases • Acids are electron pair acceptors • SO3, BF3, Al3+, CO2 Gilbert Newton Lewis

  15. LEWIS Acids and Bases • Bases: electron pair donors • NH3, O2-, H2O

  16. Traditional Examples • ammonia + boron trifluoride • NH3 + BF3 -----> H3NBF3 • Aluminum chloride + ammonia • AlCl3 + NH3 -----> Cl3AlNH3 • phosphorus trihydride and Boron trifluoride • PH3 + BF3 -----> H3PBF3

  17. LEWIS Acids and Bases • Complex ion formation is a Lewis acid Base reaction Colorful complex ions in ammonia

  18. Lewis Acids / “Complexers” • Remember the common “complexers” • Fe3+ Cu2+ Al3+ Co2+ Zn2+ Ag+

  19. Lewis Bases / “Complexers” • Ligands (bases) • CN- H2O OH- NH3 Cl- SCN- • recall the famous equilibrium complex: FeSCN2+

  20. More Lewis Acid Base (complex) examples • Aluminum nitrate solution and water • Al3+ + 6H2O -----> Al(H2O)63+ • Zinc acetate in excess sodium hydroxide solution • Zn2+ + 4OH- -----> Zn(OH)42-

  21. Lewis Acid Base (complex) examples • silver nitrate solution and concentrated ammonia solution • Ag+ + 2NH3 ----> Ag(NH3)2+ • copper II sulfate solution and excess ammonia • Cu2+ + 4NH3 -----> Cu(NH3)42+

  22. Lewis Acid Base (complex) examples • sodium cyanide solution and ferric nitrate • 6CN- + Fe3+ -----> Fe(CN)63-

  23. Complexes of centers with water • 2+ and 3+ centers • Al. Cu, Co, Fe, Zn • Complex with water • Examples…

  24. Acid Base species

  25. The Strong • perchloric, sulfuric, hydroiodic, hydrobromic, hydrochloric, nitric. • Strong bases…LI, Na, K, Ca, Sr, Ba hydroxides

  26. The Weak • Weak molecular acids: HCN, HF, HC2H3O2, H2SO3 and more. • Weak molecular bases: hydroxides of Mg, Cu, …. NH3, NH2CONH2 and more.

  27. The IONS • Acetate • Fluoride • Carbonate • Sulfite • Aluminum • Copper • Iron • Ammonium

  28. Amphiprotic • can act as either an acid or a base. • Depends on their environment.

  29. Why weak or strong? BONDING!

  30. Why weak or strong? Some ions attract H+ or OH- more than water does!

  31. HYDROLYSIS • To “split” water, react with water. • Why does it occur….

  32. Ground “rules” of hydrolysis • Anions of weak acids are basic in water. • Cations of weak bases are acidic in water. • Ions of strong acids and bases are neutral

  33. Hydrolysis Examples • magnesium iodide (a salt) • THINK: what acid and base would its ions make? • Mg2+ is from a weak base (acidic) • I- is from a strong acid (neutral) • MgI2 in water is acidic. • Mg2+ + 2H2O ----> Mg(OH)2(aq) +2 H+ • pH will be <7

  34. HYDROLYSIS • copper II bromide • THINK: what acid and base would its ions make? • Cu2+ is from a weak base and is acidic. • Br- is from a strong acid and is neutral. • CuBr2 in solution is acidic • Cu(H2O)42+ ----> Cu(H2O)3 (OH) 1+ (aq) + H+ • pH will be <7

  35. HYDROLYSIS • sodium sulfate • Neutral

  36. Hydrolysis Examples • strontium sulfite • base

  37. HYDROLYSIS • potassium acetate • BASIC! • iron III nitrate • ACIDIC!

  38. Hydrolysis Examples • sodium chloride • NEUTRAL! • cobalt nitrate • ACIDIC!

  39. HYDROLYSIS • aluminum sulfate • ACIDIC! • potassium carbonate • BASIC!

  40. How about NH4F?

  41. REMEMBER! • The “salt” of a weak base is acidic. • The “salt” of a weak acid is basic.

  42. Hydrolysis Lab…..Tuesday

  43. Acid Base Equilibria • In a reaction between acids and bases, equilibrium will favor the dissociation of the stronger acid.

  44. Weak and Strong Acids and Bases • RELATIVE STRENGTH OF Acids and Bases • See chart

  45. HC2H3O2 +H2O <===> C2H3O2-+H3O+ • Since hydronium ion is a stronger acid than acetic acid, the reactant side is favored here. Keq is small.

  46. Reason for varying acid base strength • bond strengths between ions • Strong acids and bases have WEAK bonds.

  47. Patterns • The weakest acids have the strongest conjugate bases. • The strongest acids have the weakest conjugate bases.

  48. Patterns • The weakest bases have the strongest conjugate acids. • The strongest bases have the weakest conjugate acids.

  49. Patterns • Determining factor is the bonding! • H+ acceptors vs. H+ donors

  50. Patterns • Weakest to strongest: • HCl, HBr, HI • Why? • SIZE!

More Related