1 / 11

Friday, April 5

Friday, April 5 . Work on review problems –solubility Work in groups of 3 on review problems Come up and write answer on board when you think you have the correct answer. Calculate the molar solubility of. Molar Solubility Answers. Ag 3 PO 4 ; x = 1.8 x 10 -5 M

anila
Télécharger la présentation

Friday, April 5

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. Friday, April 5 • Work on review problems –solubility • Work in groups of 3 on review problems • Come up and write answer on board when you think you have the correct answer

  2. Calculate the molar solubility of

  3. Molar Solubility Answers • Ag3PO4; x = 1.8 x 10-5 M • Al(OH)3; x = 1.0 x 10-9 M • PbCl2; x = 1.6 x 10-2 M • Ag2CrO4; x = 8.7 x 10-5 M

  4. Solubility continued The magnesium and calcium ions present in seawater ([Mg2+] = 0.059 M and [Ca2+] = 0.011 M) can be separated by selective precipitation with KOH. Calculate the [OH-] that would separate the metal ions. Kspof Mg(OH)2= 6.3 x 10-10; Kspof Ca(OH)2= 6.5 x 10-6 Ans: [OH-]: 1.03 x 10-4 M

  5. Solubility questions LEFT side: The water solubility of SrF2 is 0.011 g/ 100 mL. Calculate the solubility product constant. Ksp = 2 x 10-9 RIGHT side: The water solubility of Ag2S is 3.12 x 10-15 g/ 100 mL. Calculate the solubility product constant. Ksp = 8 x 10-48

  6. Conceptual solubility question Explain how the molar solubility of CaF2 will differ in a solution containing 0.100 M NaF compared to in a solution of pure water? Common ion effect Molar solubility of CaF2 in NaF is lower than in pure water.

  7. Buffer questions Calculate the pH of a buffer that consists of 0.45 M of C6H5COOH and 0.25 M of C6H5COONa. Ka= 6.3 x 10-5. Ans: pH = 3.94

  8. Buffer questions Now assume that the pH increased to 5.10, what are the concentrations of the buffer components? i.e.) [C6H5COOH], [C6H5COONa]? Ans: [A] = 0.078 M; [B] = 0.622 M Check: Does this make sense? Yes, an increase in pH means we have more base in solution.

  9. Buffer questions Find the pH of a buffer that consists of 0.25 M NH3 and 0.15 M NH4Cl (p­Kb of NH3 = 4.75). Approach: First find pKa. Then sub pKa into Henderson Hasselbalch equation. Ans: pH = 9.47

  10. More Buffer questions What is the ratio of [Pr-]/ [HPr] buffer that has a pH of 5.44 (Ka of HPr = 1.3 x 10-5)? Ans: [Pr-]/[HPr]= 3.55 This means need ~3.6 times more [Pr-] than [HPr] to get to pH of 5.44.

  11. Last Buffer question Last Buffer Question A buffer containing 0.2000 M of acid, HA, and 0.1500 M of its conjugate base, A-, has pH of 3.35. What is the pH after 0.0015 mol of NaOH is added to 0.5000 L of this solution? Approach: First find pKa. Set up equation showing the neutralization reaction with ICE table. Use Henderson Hasselbalch equation to solve for pH. Ans: pH = 3.37

More Related