1 / 33

Acids & Bases

Acids & Bases. (Adapted from Mrs. J’s chemistry lecture notes). Intro to Acids and Bases (Properties). ACIDS SOUR TASTE TURN LITMUS RED VINEGAR, MILK, SODA , APPLES, CITRUS FRUITS . BASES BITTER TASTE TURN LITMUS BLUE SLIPPERY FEEL AMMONIA, LYE, ANTACID, BAKING SODA. H. H. –. +. O.

jendayi
Download Presentation

Acids & 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. Acids & Bases (Adapted from Mrs. J’s chemistry lecture notes)

  2. Intro to Acids and Bases(Properties) • ACIDS • SOUR TASTE • TURN LITMUS RED • VINEGAR, MILK, SODA , APPLES, CITRUS FRUITS • BASES • BITTER TASTE • TURN LITMUS BLUE • SLIPPERY FEEL • AMMONIA, LYE, ANTACID, BAKING SODA

  3. H H – + O O Cl Cl H H H H Definitions of Acids and Bases • Arrhenius - In aqueous solution… • Acidsform hydronium ions (H3O+) HCl + H2O  H3O+ + Cl– acid

  4. H H – + N O O N H H H H H H H H Definitions of Acids and Bases • Arrhenius - In aqueous solution… • Bases form hydroxide ions (OH-) NH3 + H2O  NH4+ + OH- base

  5. conjugate base conjugate acid Definitions of Acids and Bases • Brønsted-Lowry • Acidsare proton (H+) donors. • Bases are proton (H+) acceptors. HCl + H2O  Cl– + H3O+ acid base

  6. Conjugate Acids and Bases H2O + HNO3 H3O+ + NO3– B A CA CB

  7. Conjugate Acids and Bases NH3 + H2O  NH4+ + OH- B A CA CB • Amphoteric - can be an acid or a base.

  8. Conjugate Acids and Bases F - H2PO4- H2O HF H3PO4 H3O+ • Give the conjugate base for each of the following: • Polyprotic - an acid with more than one H+

  9. Conjugate Acids and Bases Br - HSO4- CO32- HBr H2SO4 HCO3- • Give the conjugate acid for each of the following:

  10. Definitions of Acids and Bases • Lewis • Acidsare electron pair acceptors. • Bases are electron pair donors. Lewis base Lewis acid

  11. - + Strength of Acids and Bases • Strong Acid/Base • 100% ionized in water • strong electrolyte HCl HNO3 H2SO4 HBr HI HClO4 NaOH KOH Ca(OH)2 Ba(OH)2

  12. - + Strength of Acids and Bases • Weak Acid/Base • does not ionize completely • weak electrolyte HF CH3COOH H3PO4 H2CO3 HCN NH3

  13. Oxyacids, Carboxylic Acids, Polyprotic acids • Oxyacids – acids in which the acidic proton is attached to an oxygen atom (many of the above acids we talked about are of this type – may be strong or weak) • Carboxylic acids – organic acids with the “COOH” group – are usually weak • Polyprotic acids – acids that have more than one acidic proton (can give up more than one H+)

  14. Acid/Base Equilibrium

  15. Equilibrium Constant for Water(Ion Product Constant) H2O(l) ↔ H+(aq) + OH-(aq) From what we know about equilibrium expressions: Remember, we include gaseous and aqueous species, but not liquids and/or solids Kw = 1.0 x 10-14

  16. Acid Dissociation Constant HA(aq) + H2O(l) ↔ H3O+(aq) + A-(aq) ACIDBASE ↔ C ACID C BASE The equilibrium expression for this reaction is If Ka is large  strong acid (more complete dissociation) If Ka is small  weak acid

  17. Base Dissociation Constant B(aq) + H2O(l) ↔ BH+(aq) + OH-(aq) BASEACID ↔ C ACID C BASE The equilibrium expression for this reaction is If Kb is large  strong base (more complete dissociation) If Kb is small  weak base

  18. pH Refer to the pH diamond for help with the calculations

  19. pouvoir hydrogène (Fr.) “hydrogen power” pH Scale 14 0 7 INCREASING BASICITY INCREASING ACIDITY NEUTRAL pH = -log[H+]

  20. pH Scale pH of Common Substances

  21. pH Scale & Calculations pH = -log[H+] pH = -log[H3O+] pOH = -log[OH-] pH + pOH = 14

  22. pH Scale • What is the pH of 0.050 M HNO3? pH = -log[H+] pH = -log[0.050] pH = 1.3 Acidic or basic? Acidic

  23. pH Scale • What is the molarity of HBr in a solution that has a pOH of 9.6? pH + pOH = 14 pH + 9.6 = 14 pH = 4.4 [H+] = 10-pH [H+] = 10-4.4 [H+] = 4.0  10-5 M HBr Acidic

  24. Titration and Neutralization

  25. Neutralization • Chemical reaction between an acid and a base. • Products are a salt (ionic compound) and water.

  26. 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.

  27. standard solution unknown solution Titration • Titration • Analytical method in which a standard solution is used to determine the concentration of an unknown solution.

  28. Titration • Equivalence point (endpoint) • Point at which equal amounts of H+ and OH- have been added. • Determined by… • indicator color change • Dramatic change in pH

  29. Titration moles H+ = moles OH- MVn = MVn M: Molarity V: volume n: # of H+ ions in the acid or OH- ions in the base

  30. Titration • 42.5 mL of 1.3M KOH are required to neutralize 50.0 mL of H2SO4. Find the molarity of H2SO4. H2SO4 (H+) M = ? V = 50.0 mL n = 2 KOH (OH-) M = 1.3M V = 42.5 mL n = 1 MVn = MVn M(50.0mL)(2) =(1.3M)(42.5mL)(1) M = 0.55M H2SO4

  31. Buffers

  32. Buffered Solutions • Buffers are solutions that resist changes in pH when limited amounts of acid or base are added • A buffer is a mixture of a weak acid and its conjugate base or a weak base and its conjugate acid. • The mixture of ions in the buffer resists changes in pH by reacting with any H+ or OH- ions added to the buffered solution

  33. Buffers (cont’d) • The buffer capacity is the amount of acid or base a buffer solution can absorb without a significant change in pH. • A buffer system is most effective when the concentrations of the conjugate acid-base pair are equal or nearly equal.

More Related