1 / 20

Chapter 15 - Acids and Bases

Chapter 15 - Acids and Bases. Plus titration reactions from chapter 3. Arrhenius Definitions. Acid - Proton donor HA  H + + A - HCl  H + + Cl - Base - Hydroxide donor MOH  M + + OH - KOH  K + + OH -. Brønsted Lowry. Acid - Proton donor

jane-dickson
Télécharger la présentation

Chapter 15 - 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. Chapter 15 - Acids and Bases Plus titration reactions from chapter 3

  2. Arrhenius Definitions • Acid - Proton donor HA  H+ + A- • HCl  H+ + Cl- • Base - Hydroxide donor MOHM+ + OH- • KOHK+ + OH-

  3. Brønsted Lowry • Acid - Proton donor HA + H2O  H3O+ + A- • HCl + H2O  H3O+ + Cl- • Base - Proton acceptor B: + H2O  BH+ + OH- • NH3 + H2O  NH4+ + OH-

  4. HA + B <==> BH+ + A- acid base acid base Conjugate acid/ base pairs differ by 1 proton.

  5. Protons in water • We write HA <=> H+ + A- • but H+ is never found by itself -- in aqueous solutions it joins with H2O to form H3O+ • So when we write [H+] we really mean [H3O+].

  6. Acid Strength • Strong acid  weak conjugate base • Weak acid  strong conjugate base • Strong base  weak conjugate acid • Weak base  strong conjugate acid • Makes sense -- if an acid gives up a proton easily, then its conjugate base is probably not very good at grabbing protons.

  7. Dissociation of Water • 2 H2O <==> H3O+ + OH- • K = [H3O+][OH-]/ [H2O]2 • the concentration of water is ~ 55M and can be treated as a constant. • so Kw = K[H2O]2 = [H3O+][OH-] = 1.0 x 10-14 M2

  8. Definition of pH • pH = -log [H+] = -log [H3O+] • so if [H3O+] = 2.48 x 10-4 then pH = -log 2.48 x 10-4 = 3.606

  9. [H3O+] = 10-pH • so if pH = 9.431 then [H3O+] = 10-9.431 = 3.707 x 10-10 M

  10. Calculating pH and pOH for strong acids and bases • For strong acids and bases • [H+] = [acid]  acidic protons/ molecule • [OH-] = [base]  hydroxides/ molecule

  11. The strong acids and bases are • Strong acids Strong bases • HClO4 NaOH • HCl KOH • HBr soluble hydroxides • HI • H2SO4 • HNO3

  12. Remember • pH = -log [H3O+] • pOH = -log [OH-] • [H3O+] [OH-] = 1.0 x 10-14 • pH + pOH = 14

  13. What are the values of [H3O+], [OH-], pH, and pOH for a 4.287 x 10-4 M solution of Ca(OH)2?

  14. [OH-] = 2(4.287 x 10-4 M) = 8.574 x 10-4 M • pOH = -log [OH-] = -log 8.574 x 10-4 = 3.0668 • pH = 14 - pOH = 14 - 3.067 = 10.9332 • [H3O+] = 10-10.9332 = 1.166 x 10-11 M

  15. If 350.0 mL of 0.1283 M sulfuric acid is mixed with 250.0 mL of 0.2899 M sodium hydroxide, what will be the pH of the solution?

  16. A noncarbonated soft drink contains an unknown amount of citric acid, H3C6H5O7. If 100.0 mL of the soft drink requires 33.51 mL of 0.01024 M NaOH to neutralize the citric acid completely, what is the concentration of citric acid in the soft drink in moles/liter (M)? In equivalents/liter (N)?

  17. Suppose you are given a 4.554 g sample that is a mixture of oxalic acid, H2C2O4, and another solid that does not react with sodium hydroxide. If 29.58 mL of 0.550 M NaOH is required to titrate the oxalic acid in the 4.554 g sample, what is the weight percent of oxalic acid in the mixture?

  18. A vitamin C tablet was analyzed to determine whether it did in fact contain, as the manufacturer claimed, 1.00 g of the vitamin. A tablet was dissolved in water to form a 100.00 mL solution, and a 10.00 mL sample was titrated with iodine (as KI3, potassium triiodide). It required 10.10 mL of 0.0521 M I3-1 to reach the stoichiometric point in the titration. Given that vitamin C, C6H8O6, is oxidized todehydroascorbic acid, C6H6O6 and triiodide, I3-1, is oxidized to iodide, I-1, write a balanced equation for the reaction and determine whether the manufacturer’s claim is correct? (MW vitamin C = 176 g/mol)

  19. A 35.49 mL sample of 0.2430 M H2SO4 is mixed with 65.33 mL of a 0.4199 M sample of KOH. Determine the concentration of all ions in solution, the pH, and pOH.

More Related