Forensics

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Forensics
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Forensics and Safety

• Safety! Safety! Safety! Safety! Safety!
• Bring and wear lab coat/apron that cover the
  knees, OSHA approved indirectly vented splash
  goggles, pants/skirt that cover the legs to the
  ankles
• No open toed shoes
• No tasting or touching chemicals

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Students Bring to the Event!

• Test tubes/holder
• Droppers
• Funnels
• Filter Paper
• pH Paper
• Spatulas
• Stirring Rods
• Thermometer

• 9 Volt Conductivity Tester
• Flame Test Equipment
• E.g. flame spreader, nichrome wire
• Cobalt Blue Glass plate
• Metal Tongs

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Supervisors Equipment/Materials

• Lugols Solution
• 2M HCl
• 2M NaOH
• Benedicts Solution
• Hot Water Bath
• Heat Source-Flame Testing
• Distilled Water

• Matches and Candle for Fabric Burn Tests
• Various Solutions that can be used for density
  testing with polymers e.g. saltwater, alcohol,
  corn oil, or other similar materials
• Other Equipment that they choose to give

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The Competition

• Qualitative Analysis of up to 6 powders
• Polymer testing of up to 4 polymers
• Fiber analysis
• Chromatography including IR. UV, GC
  Spectrophotometry
• Fingerprint Analysis
• Analysis of the Crime

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Unknown Powders
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NaC2H3O2, NaCl, NaHCO3, Na2CO3, LiCl, KCl,
Ca(NO3)2, CaSO4, CaCO3, Cornstarch, Glucose,
Sucrose, MgSO4, H3BO3, NH4Cl
Add water
CaSO4, CaCO3, Cornstarch
NaC2H3O2, NaCl, NaHCO3, Na2CO3, LiCl, KCl,
Ca(NO3)2, Glucose, Sucrose, MgSO4, H3BO3, NH4Cl
Insoluble
Soluble
pH paper
Strong BaseNa2CO3
Weak BaseNaC2H3O2, NaHCO3
No ReactionNaCl, LiCl, KCl, Ca(NO3)2, MgSO4,
Glucose, Sucrose
AcidNH4Cl, H3BO3
Add NaOH
Optional
NH4Cl
H3BO3
NH3 odor
No odor
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Add HCl
Flame test
Add HCl
CaCO3
CaSO4
Cornstarch
Bubbles
Solution above solid clarifies
Cloudy, gelatinous
NaHCO3
NaC2H3O2
Na2CO3
No reaction
Bubbles
Bubbles
KCl
Ca(NO3)2
LiCl
NaCl, MgSO4
Glucose, Sucrose
Lavender Purple
Orange
Red
Yellow
Yellow, Burned
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Add NaOH
NaCl, Glucose, Sucrose
MgSO4
Translucent precipitate
No reaction
Add Benedicts
Glucose
NaCl, Sucrose
Orange precipitate
No reaction
Add Hot Water
NaCl
Sucrose
High solubility
Low solubility
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Fiber Analysis

• Cotton---------Burn Test and lack of odor
• Wool----------Burn Test/odor of burning hair
• Synthetic-----Melts

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Unknown Polymers

• Polyethylene
• terphthalate
• High Density Polyethylene
• Polystyrene
• Low Density Polyethylene

• Polyvinyl Chloride
• Polypropylene
• Polymethyl-methacrylate
• Polycarbonate

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Polymers

• Symbol Resin Code
• PVC 3
• PP 5
• PC 7
• HDPE 2
• LDPE 4
• PS 6
• PETE 1
• PMMA 7

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

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Polymers

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

• Densities/SP. GR.
• 1.38
• 0.90
• 1.20
• 0.95 All of these are s
• 0.92 approximate.
• 1.05
• 1.37
• 1.16

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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 Handbook of
• 1.36 Chemistry and
• 0.94 Physics
• 0.93
• 0.918

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Polymer Scheme
Unknown Polymers
floats
Add to waterSp. Gr. 1.0
Add 46 IsopropanolSp. Gr. 0.94
floats
sinks
Add to Vegetable OilSp. Gr. 0.92
floats
Add to 10 NaCl solutionSp.Gr. 1.07
sinks
PP
floats
sinks
PS
LDPE
HDPE
Contd next page
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Polymer Scheme (contd.)
Add to 10 NaCl solutionSp.Gr. 1.07
sinks
Add to saturated NaClSp. Gr. 1.36
floats
Add to 25 NaCl Sp. Gr. 1.19
floats
sinks
sinks
PC
PMMA
PETE
Burn test result- yellow flame
PVC
Burn test result- green flame
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Fingerprints

• Plain Arch
• Tented Arch
• Radial Loop
• Ulnar Loop
• Central Pocket Loop
• Double Loop
• Whorl
• Accidential

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Definitions

• Core-center or focal point of the print
• Bifurcate-the splitting of a ridge into two.
• Delta-another center or focal point of the
  fingerprint
• Ridge count-number of ridges that either cross or
  touch an imaginary line usually connecting the
  core and delta

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Jack CairnsCO-Director National Science Olympiad

• Jcairnsc_at_aol.com
• 704 N. Bradford St.
• Dover, DE 19904
• 302-734-4600