Walter White Jesse Pinkman Skyler White Mike Erhmantraut Saul Goodman Gustavo Fring

Mike’s Auto Body and Repair Gus’ Chicken & Firework Stand The River is Contaminated with metals Possible contaminants are … Ag+, Ni2+, Fe3+, Cr3+, Zn2+, and Ba2+ Who’s Guilty? Skyler’s Cement Plant & Carwash Walt’s Pharmacy and Photo Studio Jesse’s Funeral Home Ag+ Chromium is in valves and joints helps with hardness, can leach out, Ni is in metallic paints as a pigment. In film AgBr crystals are light sensitive light absorbed kicks out the e- from Br- and the e- finds a defect, the e- accumulate in the defect and then the Ag+ migrate to the defect and form Ag clusters. In developing the developer is oxidized and reduces the other Ag+ to Ag in the crystals with the Ag already present. Then you stop the reaction with sodium thiosulfate which makes Ag(S2O3)2 3- (aq) which dissolves the unexposed AgBr to leave the final image which is pure Ag. ZnO in paint (white pigment) becomes extremely brittle after 3 years zinc stearate was an ingredient in many paints. CdZnS is a yellow paint. Cr+3 Fe+3 Santa Clara River Ni2+ Zn2+ Ba2+ Mike’s Auto Body and Repair Saul’s Art Restoration Gus’ Chicken & Firework Stand

Objectives Ultimately you are given a sample of the ions from the river water and you need to determine who is guilty and bring them to justice First you will need to develop your own qualitative analysis scheme that can uniquely identify each ion in the mixture Ag+, Ni2+, Fe3+, Cr3+, Zn2+, and Ba2+

Creating your own Qualitative Analysis Scheme Start by examining how the suspect ions react with dilute HCl dilute NH3 and then conc NH3 dilute NaOH and excess NaOH and oxidation with H2O2 dilute H2SO4 You will then use these results to create a flow diagram that helps to separate and uniquely identify the ions present in a mixture

Day 1: Preliminary Tests Ag+, Ni2+, Fe3+, Cr3+, Zn2+, and Ba2+ To 10 drops of the solution add 20 drops 3M HCl Do you see any insoluble chlorides? What color are the solutions and the precipitates? To 10 drops of the solution add 1M NH3 dropwise till basic Do you see any insoluble hydroxides (gels count)? add 10 drops of concentrated 15.0M NH3 To 10 drops of the solution add 1 drop 3M NaOH. (if not basic add 6M NaOH dropwise till basic) Add 20 drops 3M NaOH and mix, do any ppts dissolve, color changes? add 10 3% H2O2 and heat of 5 mins in boiling water bath stir – note any changes To 10 drops of the solution add 5 drops of 3M H2SO4 Do you see any insoluble sulfates?

Day 1: Confirmatory Tests Ag+ test The formation of white AgCl on addition of HCl is sufficient to confirm Ag+ Fe3+ test To an Fe3+ solution (10 drops), add 5 drops of 0.2 M KSCN. This will form the complex ion Fe(SCN)63-,a deep red complex ion Cr3+ test To a CrO42- solution (10 drops), add 6.0 M HC2H3O2 until acidic; then add 2- 3 drops of 0.1 M Pb(C2H3O2)2 solution. A yellow precipitate of PbCrO4 will form Ni2+ test Take 10 drops of Ni2+ solution; make it just basic with 6.0 M NH3. To this mixture, add 10 drops of dimethylglyoxime. The formation of red precipitate confirms Ni2+ Zn2+ test To 10 drops of Zn2+ solution, add 6.0 M HNO3 until just acidic; then add 10 drops of K4Fe(CN)6. Formation of a pale yellow precipitate of K2ZnFe(CN)6 confirms Zn2+ Ba2+ test The formation of white BaSO4 precipitate, on addition of 3.0 M H2SO4, is sufficient to confirm Ba2+.