Forensics

Forensics is a Division C chemistry event that involves identification of powders, polymers, fibers, and hair samples, blood serum and fingerprint analysis, and interpretation of chromatography. Given a scenario and some possible suspects, students will perform a series of tests. These tests, along with other evidence or test results will be used to solve a crime. This event is closely associated with the Division B event, Crime Busters.

Equipment
1 or 2 people per team. Eye protection #4. 50 minutes.

Students should bring:
 * Test tubes and test tube holders (or any devices in which they can perform the tests)
 * Droppers
 * Funnels and/or filter paper
 * pH or litmus paper
 * Spatulas, plastic spoons, and/or stirring rods
 * 9-volt conductivity meter (not AC current)
 * Thermometer
 * Flame test equipment (nichrome wire, cobalt blue glass, etc.)
 * Slides and cover slips
 * Hand lens
 * Writing instruments
 * A pencil and ruler (for chromatograms)
 * Paper towels
 * Metal tongs
 * A 8.5".11" two sided page of any notes containing information in any form from any source
 * Non-programmable calculator

Event proctors will provide: Event proctors may provide:
 * Iodine reagent
 * 2M HCl
 * 2M NaOH
 * Benedict's solution
 * Hot water bath
 * A Bunsen burner or something similar
 * A waste container
 * Chromatography materials
 * A wash bottle with distilled water
 * Other equipment (microscope, probes, etc.)
 * Candle & matches if fibers given
 * Differential density solutions or other method of determining density if plastics are given
 * Reagents to perform other tests

Topics Covered

 * Qualitative Analysis (powders)
 * Polymers
 * Chromatography/Spectroscopy
 * Fingerprint Analysis
 * DNA
 * Glass Analysis
 * Entomology
 * Spatters
 * Seeds and Pollen
 * Tracks and Soil
 * Blood
 * Bullet Striations

Qualitative Analysis
Qualitative Analysis is the section of the test that involves the identification of unknown powders. At the regional level, 3-8 powders will be given. 6-10 samples will be given at state, and 8-12 powders will be given at nationals. It is helpful to include a flowchart to aid with powders identification on your cheat sheet.

There are sixteen different substances that may be given on a test: sodium acetate, sodium chloride, sodium hydrogen carbonate (sodium bicarbonate), sodium carbonate, lithium chloride, potassium chloride, calcium nitrate, calcium sulfate, calcium carbonate, cornstarch, glucose, sucrose, magnesium sulfate, boric acid, and ammonium chloride. Utilizing all your availible means of identification will give the best results.

Methods of Identification

Flame test: The flame test uses a Bunsen burner and a nichrome wire. To perform this test, dip a clean nichrome wire in distilled water, and then dip the loop of the wire into a small sample of the dry chemical. Hold the loop of the wire in the cone of the flame, and observe the color of the burning chemical. If desired, a piece of cobalt blue glass may be used for viewing. Chemical anions determine the color of the flame, and their characteristics may indicate the chemical identity. Tests with liquids: Iodine, Sodium Hydroxide, Hydrochloric Acid, Benedict's solution, Water, Ammonium Chloride
 * Sodium: yellow flame

pH:

Conductivity:

Solubility:

Hints
 * Try to use solubility
 * How they react with the chemicals provided
 * Utilize pH
 * Burn tests can be used if necessary, but are only effective with K, B, and Li compounds (because their color is really distinct).
 * Becoming familiar with the chemicals is the key to success. Memorizing properties and reactions of powders will greatly aid in their identification.

Polymers
Methods of Identification
 * Burn test (fibers and hair only)
 * Density in liquids--oil, water, alcohol, etc. (plastics)

Hints Burn tests for fibers, when permitted, will usually be done with a small candle (Bunsen burners are too hot). Burn tests on plastics will not be permitted at the event, but burn test results may be provided. If not, it is important to know densities and other identifying properties. Common liquids used to test plastic densities include water, vegetable oil, isopropyl alcohol, and NaCL solution.