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Crime Busters

Crime Busters. Piedmont IB SO Workshop #2. What is required for success. Chemistry knowledge Common sense Logical thinking memory Speed ! Work hard!. What you will learn. Chemistry Flow charts/problem solving skills. Topics covered. Powders Metals (nationals) Liquids (nationals)

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Crime Busters

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  1. Crime Busters Piedmont IB SO Workshop #2

  2. What is required for success • Chemistry knowledge • Common sense • Logical thinking • memory • Speed ! • Work hard!

  3. What you will learn • Chemistry • Flow charts/problem solving skills

  4. Topics covered • Powders • Metals (nationals) • Liquids (nationals) • Fibers and plastics • Paper chromatography • Crime Scene Physical Evidence • Evidence analysis

  5. Powders Able to identify the following powders Cornstarch Baking soda Powdered gelatin Powdered Alka-Seltzer Yeast Borax talc • Sodium acetate • Sand • Calcium carbonate (powdered limestone) • Vitamin C (Ascorbic acid) • Table salt • Sugar • Flour

  6. Metals(Nationals only) • Aluminum • Iron • Zinc • Magnesium • Copper • tin

  7. Liquids(Nationals only) Able to identify the following liquids • Lemon juice • Rubbing alcohol • Household ammonia • Water • Vinegar • Hydrogen peroxide

  8. Polymers, hair and fibers Fibers (national) Hair (National) Polymers PETE HDPE Non-expanded PS LDPE PP PVC • Human • Dog • Cat • Animal • vegetable • synthetic

  9. Paper chromatograph(National) • To identify ink, juices, and other colored materials • Easy to do. Compare unknown with known materials

  10. Physical evidence • Finger prints • Patterns (whorls, loops, arches) • Compare known to unknown • Irises

  11. Evidence analysis • Logical thinking • Speed and clarity

  12. How to identify powders Reaction with Iodine Other characteristics • Appearance/physical properties • Color • Texture • Odor/smell • Density • Water solubility/pH • Reaction with HCl • Rate of reaction • Gas formation • Disappearance of insolubles • smell

  13. Example of powder identification Sodium acetate • Colorless needles or white powder • Very water soluble • pH = 8.9 • Smells like vinegar when HCl is added, no other visible reactions

  14. How to identify Metals • Appearance/physical properties • Color • Is it shiny? • Density • Attraction by magnet • Reaction with HCl • Rate of reaction • Gas formation • Heat generation

  15. How to identify liquids • Smell • Clarity • pH

  16. How to identify hair • Microscope • Visual observation

  17. How to identify fibers- only required to distinguish between animal, natural, and synthetic • Physical properties • Diameter of fiber • Is it straight or curled? • Is it stretchy? • Micrographs provided • Burning observations (provided)

  18. How to identify plastics • Appearance • Color • Clarity • Density, using solutions of known density • Burning properties

  19. Paper chromatography • Separation of colors (possibly) • Relative position of spots • Used to identify the source of ink, juice, and other colored materials

  20. Finger prints • Remember the different patterns • Whorls • Loops • Arches • Compare unknown with knowns • Could be partial prints • Know where to look at

  21. DNA • Similar to paper chromatography in principle, but uses high tech to look at DNA patterns • Compare known with unknown • Use common sense

  22. Shoeprints and tire treads • Patterns • Speed and direction of travel

  23. Irises • Unique like finger print • Some EU countries started using Iris scan

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