Science Crime Busters Lin Wozniewski

Safety Students must wear: –Closed shoes –Slacks or skirts that come to the ankles –Sleeved shirts –Lab coat or lab apron –Indirect vent or unvented chemical splash proof goggles. No impact glasses or visorgogs are permitted

Students can bring Spot plate or something to do reactions in Spoon or something to get powders out Forceps pH paper Magnet Hand lens

Students Can Bring Slide & cover slip Pencil Paper towels 1 sheet of paper on which anything handwritten is acceptable. A writing instrument Nothing else is allowed

Supervisors will provide Unknowns Iodine Solution 1 M HCl Data Collection Device w/ probes Chromatography Materials Wash bottle with Distilled or ROI water Waste Container Microscope Other Reagents

Main Focus  Chemical Analysis  Water Testing  Chromatography  Crime Scene Physical Evidence  How to prepare students  Resources

Qualitative Analysis Liquids, except for water and hydrogen peroxide, can be ID by either looking at them or wafting them Metals can ID by looking at them or putting a magnet by them, or seeing how fast they react with water & HCl Single powders (event supervisors MUST tell the students which are mixtures and how many powders are present if any have more than two) can often be ID by a quick glance, or a test or two.

Water Testing Students might need to test for heavy metals using a calibration graph and a colorimeter. Students might need to test for specific ions using specific ion probes (such as Ammonium, Calcium, Nitrates, etc.) Students might be asked to test for Dissolved Oxygen using a DO probe Students might be asked to test for turbidity using a turbidity probe. Students might be asked to test for Total Dissolved Solids (TDS) using a conductivity probe Students may be asked to determine if a source of pollution is from a point or non-point source

Chromatography At this level, the students can only be asked to do paper chromatography. Students need to know how to spot both pens and juices Students need to know how to do both strip and sheet chromatograms. Students need to know to mark the line to spot on and the type of material with a pencil

“Fun” Forensic Physical Crime Scene Evidence Students need to know the basic three types of fingerprints Students need to be able to match pretty pictures of DNA Students need to be able to match the positive and negative shoes/footprints and Tires/Tire Tracks

How To Prepare Students Have students develop a dichotomous key for identifying chemicals Practice identifying chemicals in as short a time as possible. Practice identifying powders mixed in groups of 2 & 3 Practice testing water Practice doing pen chromatograms Practice doing juice chromatograms

How to Prepare Students Practice identifying fingerprints Practice matching DNA chromatograms/electropherograms Practice matching shoes & tires to their tracks Try a liquid spatter activity Practice using a waste container

Resources The National SO Website

Questions? Thank You