Science Crime Busters

Division B

Andy Shaw

Sr. Research BiochemistMerck & Co.

West Point, PA

Ph.D. in ChemistryUniversity 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

Liquid Observation Odor React w/I2 pH

Water Colorless, Clear None None ~6

Ammonia Cloudy, especially after shaking

Sharp, strong

None ~10

Hydrogen Peroxide

Colorless, Clear, Bubbles when shaken

None Bubbles ~6

Lemon Juice Cloudy, yellowish Light None ~2

Rubbing Alcohol

Colorless, Clear Sweet None ~6

Vinegar Colorless, Clear Strong None ~2

Bleach Slightly Yellowish Strong Clears color ~10

Liquid Identification Flow Chart

No

Yes

No

Yes

Cloudy?

YespH~10?

YesAmmonia

No

pH~2? Lemon Juice

No

Odor?

Yes

Rubbing Alcohol

Yes

pH~2?Yes

Vinegar

No

Bubbles when shaken?

Hydrogen Peroxide

Water

Bleach

No

Sweet?

Metal Identification

Metal Observations Mag-netic?

Water HCl

Aluminum Gray, Dull, sometimes shiny No No Reaction Delayed reaction

Copper Yellow or Brownish No No Reaction No Reaction

Iron Dark Yes No Reaction Delayed reaction

Magnesium Dull, Light metal No Delayed Tiny bubbles

Immediate violent reaction

Tin Yellowish tinge No No Reaction Little if any reaction

Zinc Shiny, dense (heavy) metal no No Reaction Immediate violent reaction

Metal Identification Flow Chart

No

Yes

Very tiny bubbles

Yes

Yes

No

Magnetic?Yes

Iron or an Iron Alloy

React w/water? Magnesium

No

React w/acid?Yes

Fast? Zinc

NoNo

Tin or a Tin AlloyAluminum

Yellowish?Copper or a Copper Alloy

Qualitative Analysis Flow Chart

Qualitative Analysis Flow Chart

Polymers

Densities/SP. GR.

1.38

0.90

1.20

0.95

0.92

1.05

1.37

1.16

Name• Polyvinylchloride• Polypropylene• Polycarbonate• High Density polyethylene• Low Density polyethylene• Polystyrene• Polyethyleneterephthalate• Polymethylmethacrylate

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).

Boot Print Analysis

At the Division B level, students are expected

to match the prints

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 X X X X X

Chromato-graphy

X X X

DNA X X X X X

Prints X X X

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.