User:Beatriz Gimenez De C./Notebook/571/2014/10/21: Difference between revisions

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* Prepare iodide ion selective electrodes
* Prepare iodide ion selective electrodes
**Prepare 10 mL 3 M NaCl
**Prepare 10 mL 3 M NaCl
***Carefully remove yellow plastic covering on Ag/AgCl electrode (as instructed)
***Place electrode in 15 mL falcon tube with enough NaCl solution to match volume in electrode
***Place electrode in 15 mL falcon tube with enough NaCl solution to match volume in electrode
***cover and store upright until needed
***cover and store upright until needed

Revision as of 18:33, 31 October 2014

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Tasks

  • Prepare Dialysis for 30:1 Colloid vs CaCl2
  • Prepare iodide ion selective electrodes
    • Prepare 10 mL 3 M NaCl
      • Place electrode in 15 mL falcon tube with enough NaCl solution to match volume in electrode
      • cover and store upright until needed
    • Prepare 50 mL 4 M KNO3
      • Add KNO3 to outer double junction cell, filling narrow tube + ~ 0.5 inches further
      • Place electrode in small vial with enough KNO3 solution to cover the vycor tip
    • Prepare 50 mL 0.01 M KI + 0.1 M KNO3
      • Cut a short piece (~ 3 in) of silver wire
      • Place in KI/KNO3 solution
      • Electrolyze the solution using the power supply
      • The standard reduction potential for Ag/AgI is -0.15 V
      • Oxidation occurs at the anode, which is connected to the red lead
      • Electrolyze at low power (low current) until the wire appears coated
    • Test your electrodes with a range of KI solutions
      • The Ag/AgCl electrode slides inside of the KNO3 bridge solution (this is a double junction electrode)
      • The Ag/AgI wire can be connected directly to a multimeter using alligator clips
      • You will continue to connect your Ag wire to the red lead on the multimeter
Ki concentrations (mM) Voltage (mV) ln[I-]
50 -278 3.912023005
25 -247.4 3.218875825
10 -237 2.302585093
5 -217.4 1.609437912
2 -198.3 0.693147181

  • Prepare new KI Stock Solution (the previous KI solutions were discarded because there was an error with the dilutions that were prepared)
    • 50 mM KI (0.83 g KI in 100 mL H2), which through dilution:
      • 25 mL 25 mM KI
      • 25 mL 10 mM KI
      • 25 mL 5 mM KI
      • 25 mL 2 mM KI
  • 10 mM NH4SCN (0.7612 g NH4SCN in 1 L H2)
  • 75 mM AgNO3 (0.637 g AgNO3 in 50 mL H2)


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