FORENSICS SCIENCE OLYMPIAD CHEAT SHEET (C Division)
1. QUALITATIVE ANALYSIS – POWDER ID GUIDE
- Sodium acetate: pH~8, soluble, no HCl rxn.
- Sodium chloride: neutral, soluble.
- Sodium bicarbonate: basic, mild fizz in acid.
- Sodium carbonate: strong base, strong fizz in HCl.
- Lithium chloride: neutral, crimson flame.
- Potassium chloride: neutral, lavender flame.
- Calcium nitrate: soluble, slightly acidic.
- Calcium sulfate: low solubility.
- Calcium carbonate: fizz in HCl, insoluble.
- Cornstarch: iodine → blue-black.
- Glucose: mild acid, soluble.
- Sucrose: neutral, soluble.
- Magnesium sulfate: soluble, needle crystals.
- Boric acid: weak acid, low solubility.
- Ammonium chloride: sublimation → NH3 on heating.
2. POLYMERS
Plastics (no burn tests):
PETE (#1, sinks), HDPE (#2 floats), PS (#6 brittle), LDPE (#4 flexible), PP (#5 floats), PVC (#3 sinks),
PMMA (brittle), PC (tough).
Fibers (burn tests allowed):
Cotton burns like paper; Wool & Silk self-extinguish smell like hair; Linen burns; Nylon melts, celery
smell; Spandex melts fast; Polyester melts sweet odor.
Hair ID:
Human=imbricate; Bat=coronal; Squirrel=banded; Cow/Horse=thick medulla.
3. CHROMATOGRAPHY & SPECTROSCOPY
- Rf = distance solute / distance solvent.
- Mass spec: M+ peak = molar mass; base peak highest; Cl 3:1, Br 1:1 isotopes.
4. CRIME SCENE EVIDENCE
Fingerprints:
Patterns: plain arch, tented arch, radial loop, ulnar loop, plain whorl, central pocket whorl, double loop
whorl, accidental whorl.
