Co_Ni_Lab_Lec - 4 2-fully forms only in 9 M Cl-. Completely...

Info iconThis preview shows pages 1–9. Sign up to view the full content.

View Full Document Right Arrow Icon
Co 2+ /Ni 2+ Assay Chem 223
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Major ideas simultaneous measurement of mutually interfering species vs. separation before determination complexation to form colored species stable precursors leading to unstable reactants ion exchange chromatography, ion-pairing gradient elution importance of organization, planning ahead, visualizing why each step is performed, glassware cleanliness
Background image of page 2
Two Weeks Work Week I : obtain sample. Keep one part as mixture. Pass another part through an ion-exchange column to separate Co 2+ from Ni 2+ in preparation for determinations, Week 2. Week II : complex specimens. Measure absorbance for samples and standards.
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Sample Vol. Flask with 75 mL 12 M HCl Dilute to 100 mL Diluted mixed unknown Ni 2+ Standard Co 2+ Standard Diluted Ni 2+ Standard Diluted Co 2+ Standard Anion Exchange Chromatography Diluted Ni 2+ fraction Diluted Co 2+ fraction Week 1
Background image of page 4
Ion Exchangers
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
1. Collect to completion as shown by DMG or SCN test. 2. CoCl
Background image of page 6
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Background image of page 8
Background image of page 9
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: 4 2-fully forms only in 9 M Cl-. Completely dissociated in 4 M Cl-. 3. Must complete chromatography during first week! S-2-(3-mercaptoquinoxalinyl) quinoxaline-2-3-dithiol thiuronium chloride (plus urea) Stable Unstable Co 2+ + 2Q CoQ 2 2-+ 4H + Ni 2+ + 2Q NiQ 2 2-+ 4H + Dont forget to soak 10 each 25 mL volumetric flasks in dilute nitric acid for the next lab group. HNO 3 protonates glass surface removes adsorbed, interfering cations destroys metal/quinoxaline complex hydrolyzes remaining quinoxaline 2,3 dithiol In Advance of Week 2 Week 2 Form complexes (Ni complex forms fast at room temperature; Co is slow, requires heating to 60 C. What happens at T>60 ?) Blank = Q reagent in buffer only Ni working curve Co working curve Absorbance measurements for unseparated unknown, separated Ni, separated Co...
View Full Document

This note was uploaded on 01/06/2011 for the course CHEM 223 taught by Professor Scheeline during the Fall '08 term at University of Illinois at Urbana–Champaign.

Page1 / 9

Co_Ni_Lab_Lec - 4 2-fully forms only in 9 M Cl-. Completely...

This preview shows document pages 1 - 9. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online