HW Lab 25 Group III

HW Lab 25 Group III - Lab 25 Group III Prelab Questions:...

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Lab 25 Group III Prelab Questions: Use Discussion information starting p.77 1) Basis of separation a) The aluminum group form insoluble metal hydroxides while nickel group form soluble ammonia complexes b) Ppt using NaOH/H2O2 c) Dissolve zinc sulfide using 1 M HCl 2) Purpose of procedure a) To oxidize Fe2+ to Fe3+ to alter hydroxide solubility b) To allow you to see the colorless Al(OH)3 ppt c) Ether acts as a solvent for the transient blue intermediate d) To form a basic solution. The Ni(DMG)2 (s) is soluble in acidic soln. 3) Reagent Solid Ion in Solution a) Thioacetamide SnS2 Ni 2+ b) HNO3, NH3/NH4Cl Al(OH)3 Cr3+ c) NH3/NH4Cl Fe(OH)3 Zn2+ d) Cold dilute HCl PbCl2 Co2+ Or thioaetamide PbS Co2+ e) Thioacetamide Bi2S3 Cr3+ f) 1 M HCl NiS Zn2+ 4) Confirmation a) Al3+ Confirmation Reagent: aluminon dye Confirming Reaction: Al3+(aq) + 3 OH-(aq) + aluminon dye Al(OH)3.aluminon (s) Confirming Observation: red lake b) Chromium Confirmation Reagent: HNO3, ice-cold H2O2/ether Confirming Reaction: Cr2O72-(aq) + 3 H2O2(aq) + 8 H+(aq) 2 Cr3+(aq) + 3 O2(g) + 7 H2O Confirming Observation: transient blue color c) Fe3+ Confirming Reagent: NH4SCN Confirming Reaction Fe3+(aq) + SCN-(aq) FeNCS2+ (aq) Confirming Observation blood red soln d) Zn2+ Confirming Reagent NH3/thioacetamide/80oC/5 minutes Confirming Reaction Zn(OH)42-(aq) + HS-(aq) 3 OH-(aq) + H2O(l) + ZnS(s) Confirming Observation white ppt e) Ni2+ Confirming Reagent dimethylglyoxime (HDMG) Confirming Reaction Ni(NH3)62+ (aq)+ 2 HDMG (aq) Confirming Observation brilliant red ppt f) Co2+ Confirming reagents: NH4SCN, acetone. 2 NH4+ (aq) + 4 NH3 (aq) + Ni(DMG)2(s) Confirming Reaction Co2+ (aq) + 4 SCN- (aq) Co(NCS)42-(aq) Confirming Observation blue soln ...
View Full Document

This note was uploaded on 04/19/2008 for the course CHEM 123 taught by Professor Larosa during the Spring '06 term at Ohio State.

Ask a homework question - tutors are online