Difference between revisions of "Forensics"

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'''Forensics''' is a chemistry event that involves identification of powders, polymers, fibers, and hair samples, blood serum and fingerprint analysis, and  interpretation of chromatography.
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'''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.
 
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]].
 
This event is closely associated with the [[Division B]] event, [[Crime Busters]].

Revision as of 20:27, 20 June 2011


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:

  • 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

Event proctors may provide:

  • 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

Methods of Identification:

  • Flame test
  • Tests with liquids: Iodine, Sodium Hydroxide, Hydrochloric Acid, Benedict's solution, Water, Ammonium Chloride
  • pH
  • conductivity
  • solubility in water

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)

Other 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.