Science Crime Busters Division B

Sr. Research Biochemist University of Illinois Andy Shaw Sr. Research Biochemist Merck & Co. West Point, PA Ph.D. in Chemistry University of Illinois 7 years involvement with Science Olympiad 5 years State Event Supervisor 3 years Regional Event Supervisor 2005 National Event Supervisor 2006 Coaches Clinic Presenter

Event Parameters A team of 2 students competes for 50 minutes to analyze crime scene evidence and write a summary of their analysis Scoring: Qualitative analysis: 50% Physical evidence: 25% Essay of the analysis: 25%

Rule Changes Cheat Sheet!! – Students may bring handwritten notes on both sides of a 8.5 x 11 sheet of paper Supervisors will not provide a list of unknowns Changes to number of unknowns Changes to polymers tested Multiple pieces of physical evidence (fingerprints, DNA, shoe prints, tire treads, and spatters) will be tested

General Safety Precautions Safety! Safety! Safety! Safety! Safety! Bring and wear lab coat/apron that cover the knees, OSHA approved indirectly vented splash goggles (over the eyes), pants/skirt that cover the legs to the ankles (no shorts) No open toed shoes No tasting or touching chemicals

Equipment Provided by Student Small containers/reaction plates Wood splints or plastic spoons pH paper Forceps and microscope slides Magnet Hand lens Paper towels Pencils NO CALCULATORS

Equipment Provided by Supervisor Iodine solution 1 M HCl Paper chromatography materials chamber, solvent, paperclips, etc. Waste container Distilled water Liquids for density test of polymers

Unknown Analysis Identify metals, liquids, and powders Students should be familiar with common uses for each compound Students should develop a strategy for identification (see flow charts) Some mixtures of powders may be given

Liquid Identification Observation Odor React w/I2 pH Water Colorless, Clear None ~6 Ammonia Cloudy, especially after shaking Sharp, strong ~10 Hydrogen Peroxide Colorless, Clear, Bubbles when shaken Bubbles Lemon Juice Cloudy, yellowish Light ~2 Rubbing Alcohol Sweet Vinegar Strong Bleach Slightly Yellowish Clears color We will be looking at how you would test liquids. Although we are only going to look at six common liquids you might expect to find around the house, the methods for identifying the liquids are similar. The five liquids we will be learning to identify are water, vinegar, lemon juice, hydrogen peroxide ammonia, and rubbing alcohol. The first test we will do is a simple matter of observing the solutions. Some of the solutions will all look the same at first. But if you look close you will notice a difference. Shake all of the liquid vials and see what happens. The second test we will do is smell. This is an easy test and is one of the best at identifying the unknowns. But it is not as easy as it sounds. One thing a scientist does not want to do is put a chemical right under their nose and inhale. This is very dangerous. If the chemical is concentrated or a health hazard this can make you very sick or very dead. Therefore, what we do is hold the chemical container out in front of our faces by a few inches. Then we bring a hand toward our nose passing the hand over the top of the open container of the liquid. This will bring just enough of the vapors of the liquid to our noses to smell. The last test we will do is to test the pH of the liquids. We do this by dipping the glass-stirring rod in the liquid and then touching the rod to a piece of pH paper. We then compare the color against the chart on the side of the vial the pH paper was in. Here is a chart similar to the one you will fill out. Do your findings agree?

Liquid Identification Flow Chart No Yes Cloudy? pH~10? Ammonia pH~2? Lemon Juice Odor? Rubbing Alcohol Vinegar Bubbles when shaken? Hydrogen Peroxide Water Bleach Sweet? Most of the liquids are fairly straight forward to identify. But students should not get in the habit of using the process of elimination as a method of analyzing the liquids. On most of my crime scenes the same liquid is used more than once. It may be found at the crime scene and on one or more of the suspects. Students are then expected to use this evidence as a way of implicating or not implicating the suspect. The most difficult identification is water or hydrogen peroxide. Hydrogen peroxide naturally decomposes into oxygen and water. It is easy to tell fresh hydrogen peroxide because if the vial or bottle is shaken, the decomposition reaction will be accelerated and the bubbles of oxygen will be easily seen. The spontaneous decomposition oxygen bubbles of older hydrogen peroxide will not be as easy to see. If the suspected hydrogen peroxide is mixed with the Iodine solution, the decomposition reaction will be catalyzed and the bubbles will be seen. If the hydrogen peroxide is even older, this may not work. If yeast is one of the powder unknowns, then the yeast can be mixed with the suspected hydrogen peroxide. The yeast will again catalyze the decomposition reaction. If the hydrogen peroxide is so old that all of the hydrogen peroxide has spontaneously decomposed, it is water, not hydrogen peroxide!

Metal Identification Metal Observations Mag- netic? Water HCl Aluminum Gray, Dull, sometimes shiny No No Reaction Delayed reaction Copper Yellow or Brownish Iron Dark Yes Magnesium Dull, Light metal Delayed Tiny bubbles Immediate violent reaction Tin Yellowish tinge Little if any reaction Zinc Shiny, dense (heavy) metal no Just as one can identify a liquid by it’s properties, one can also identify a metal by how it behaves. Of course we can not really use smell as a method of identification with a metal, but instead we can use how it reacts with other substances. We can not look at all of the metals. There just is not time. Forensic scientists may use many of these same techniques when they have to identify a metal found on a victim or a suspect. Many times they use these techniques in cases of hit and run drivers. Forensic scientists also have more sophisticated techniques available to be sure they have correctly identified the metal. Some metals are alloys, which means that they were melted to their liquid state and then two or more different metals were mixed together. When the alloy cools, it is actually a metal that has some of the properties of all the metals that were mixed together to make up the alloy. The properties of the alloy will be different depending on the proportions of the various metals mixed. Then it is important to find out, not only what the metal is, but the proportions of the metals that made up the alloy. Unfortunately this is very time consuming and we just do not have the time to do it.

Metal Identification Flow Chart No Yes Very tiny bubbles Magnetic? Iron or an Iron Alloy React w/water? Magnesium React w/acid? Fast? Zinc Tin or a Tin Alloy Aluminum Yellowish? Copper or a Copper Alloy

Qualitative Analysis Flow Chart

Qualitative Analysis Flow Chart

Polymers Name Densities/SP. GR. Polyvinylchloride 1.38 Polypropylene Polycarbonate High Density polyethylene Low Density polyethylene Polystyrene Polyethyleneterephthalate Polymethylmethacrylate Densities/SP. GR. 1.38 0.90 1.20 0.95 0.92 1.05 1.37 1.16 Values are approximate

Densities of Common Solvents Water 10% Salt Water 20% “ “ 25% “ “ Saturated NaCl 50% Ethanol/water 70% Isopropanol Mazola Oil 1.0g/ml 1.07 1.15 1.19 1.36 0.94 0.93 0.918 Source: Handbook of Chemistry and Physics

Chromatography Chromatography results may vary depending on solvent For example, isopropanol vs. water If solvent is provided, use it Chromatography samples generally run slow and need to be run longer than students think (15-20 minutes) Ink samples spotted on filter paper Isopropanol as solvent Suspects 3 & 6 computer ink matches computer printout found at scene

Fingerprint Analysis At the Division B level, students are expected to match fingerprints, not to use whorl, loop, arch terminology or explain how prints are obtained

DNA Analysis At the Division B level, students are expected to match the patterns of bands on a gel that simulates DNA sequencing

Hair Analysis Taken from Science Olympiad website (on last slide).

At the Division B level, students are expected to match the prints Boot Print Analysis At the Division B level, students are expected to match the prints

X = implicated by evidence Analysis of the Crime What does each piece of evidence mean by itself? How does all the evidence fit together? Make a table: Steven Michael Daniel Josephine Robert Genevieve Unknowns X Chromato-graphy DNA Prints X = implicated by evidence

Tips from the Supervisor “A good note sheet is key” Have a list of chemical reactions, fiber analysis, types of fingerprints, etc. Time is a factor: 33% of teams finshed at regional, 10% finished at state Students did best on the powder and fingerprint tests, and struggled on polymer and fiber analysis. Practice running chromatography

Additional Resources Visit the Science Crime Busters webpage at the Science Olympiad website: http://www.soinc.org/events/scicrime/index.htm This has many links to resources that are helpful in preparing for the event. It also has links to places you can order fiber and polymer kits.