Chem 250 exam #2  review sheet

  1. Titrimetric methods = volumetric analysis
  2. standard solution
  3. titration
  4. equivalence point
  5. titration errors
  6. indicators
  7. primary standards and requirements
  8. secondary standards
  9. M = molarity   M = moles solute/ liter solution
  10. N = normality  N = equivalents / liter of solution
  11. preparing a standard solution from a solid
  12. preparing a standard solution from a conc. Solution MdVd=McVc
  13. method of back titration
  14. weak acids, weak bases and buffers
  15. conjugate pairs
  16. pH, pOH
  17. Kw = 1.000 x 10 -14 at 25 C
  18. polyprotic acids, salts of polyprotic acids
  19. amphiprotic substances
  20. KaKb = Kw for a conjugate pair
  21. zwitter ions
  22. strong acids and strong bases
  23. differentiating solvents, leveling solvents
  24. Keq expression, Ka expression, Ka expression, Ksp expression
  25. Henderson-Hasselbach equation for acidic buffers
  26. Henderson-Hasselbach equation for basic buffers
  27. choosing the conjugate pair to buffer around the desired pH range
  28. making buffers
  29. acid-base indicators and pH ranges    pH = pKa + 1
  30. titration curves  SA/SB , WA/SB , SA/WB
  31. as Ka increases   DpH/ DmL increases  so sharper endpoint
  32. calculations at different points on the pH titration curves for example just the acid, buffer region, eq. pt., excess base
  33. complex acid systems, complex base systems
  34. mixtures of strong acids and weak acids
  35. polyprotic acids, polyprotic bases
  36. regions on the pH titration curves and corresponding calculations for polyprotic acids and salts of polyprotic acids
  37. complex ions, ligands
  38. dentate, monodentate, bidentate, tetradentate, hexadentate
  39. donor atom
  40. EDTA is hexadentate
  41. chelating ligand
  42. wt/wt % , ppt, ppm, ppb
  43. wt/vol %, ppt, ppm, ppb
  44. EDTA titrations are 1:1 metal ion to EDTA because EDTA is hexadentate
  45. complexiometric titrations
  46. EDTA complex ion is colorless not colored
  47. Water hardness EDTA titration. How the indicators work.
  48. EDTA titrations are pH dependent.
  49. Figure 17-9 most stable EDTA complex pH
  50. At least tetradentate ligands for a sharp endpoint
  51. EDTA abbreviated H4Y. The four H+ are removed so four K’s
  52. H4Y ó K1   H3Y- ó K2  …
  53. Fig 17-2  “the roller coaster” of EDTA
  54. a0 , a1 , a2 , a3 , a4  what they mean
  55. calculation of a4
  56. EDTA water hardness titration needs to have a pH of 10. Control the pH with a buffer.
  57. Na2H2Y is the form of EDTA used in titrations because it dissolves easier.
  58. EDTA bonds with +2 or higher charged metal ions
  59. EDTA can be used as a food preservative
  60. Ligands can also be used to mask ions. Called masking agents. Very useful if a metal cation is causing an interference.
  61. All lectures, all labs, all homework, all CC’s , all CQ’s pertaining to this material

 

 

Bring to the Exam

  1. pencils/pens
  2. calculator
  3. four information sheets  8 ½ “ x 11 “ one side only with your name on the back

 

A Ka, Kb table will be provided

An indicator pH range table will be provided

A periodic table or a table of molar masses will be provided

Fig 17-2 the roller coaster will be provided

Fig 17-9 will be provided