Forensics

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

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

Supervisor’s Equipment/Materials

• Lugol”s Solution• 2M HCl• 2M NaOH• Benedict’s 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

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

Unknown Powders

NaC2H3O2 NaCl NaHCO3

Na2CO3 LiCl KCl

Ca(NO3) 2 CaSO4 CaCO3

Cornstarch Sucrose Glucose

MgSO4 H3BO3 NH4Cl

NaC2H3O2, NaCl, NaHCO3, Na2CO3, LiCl, KCl, Ca(NO3)2, CaSO4, CaCO3, Cornstarch, Glucose, Sucrose, MgSO4, H3BO3, NH4Cl

CaSO4, CaCO3, Cornstarch

NaC2H3O2, NaCl, NaHCO3, Na2CO3, LiCl, KCl, Ca(NO3)2, Glucose, Sucrose, MgSO4, H3BO3, NH4Cl

Add water

Insoluble Soluble

pH paper

Strong BaseNa2CO3

Weak BaseNaC2H3O2, NaHCO3

No ReactionNaCl, LiCl, KCl, Ca(NO3)2, MgSO4, Glucose, Sucrose

AcidNH4Cl, H3BO3

NH4Cl H3BO3

Add NaOH

NH3 odor No odor

Optional

Add HCl

CaCO3 CaSO4 Cornstarch

Bubbles Solution above solid clarifies

Cloudy, gelatinous

Flame test Add HCl

NaHCO3 NaC2H3O2 Na2CO3

No reactionBubbles Bubbles

KCl Ca(NO3)2 LiCl NaCl, MgSO4 Glucose, Sucrose

Lavender Purple

Orange Red Yellow Yellow, Burned

Add NaOH

NaCl, Glucose, SucroseMgSO4

Translucent precipitate

No reaction

Add Benedicts

GlucoseNaCl, Sucrose

Orange precipitate

No reaction

Add Hot Water

NaCl Sucrose

High solubilityLow solubility

Fiber Analysis

• Cotton---------Burn Test and lack of odor

• Wool----------Burn Test/odor of burning hair

• Synthetic-----Melts

Unknown Polymers

• Polyethylene terphthalate

• High Density Polyethylene

• Polystyrene

• Low Density Polyethylene

• Polyvinyl Chloride

• Polypropylene

• Polymethyl-methacrylate

• Polycarbonate

Polymers

NamePolyvinylchloride

Polypropylene

Polycarbonate

High Density polyethylene

Low Density polyethylene

Polystyrene

Polyethyleneterephthalate

Polymethylmethacrylate

Symbol Resin CodePVC 3

PP 5

PC 7

HDPE 2

LDPE 4

PS 6

PETE 1

PMMA 7

Polymers

NamesPolyvinylchloride

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

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

Polymer SchemeUnknown Polymers

Add to water—Sp. Gr. 1.0

sinks

floats

Add to 10% NaCl solution—Sp.Gr. 1.07

Add 46% Isopropanol—Sp. Gr. 0.94

Add to Vegetable Oil—Sp. Gr. 0.92

floats

PP sinks

LDPE

floats

sinks

HDPE

floats

PS

Cont’d next page

Polymer Scheme (contd.)

Add to 10% NaCl solution—Sp.Gr. 1.07

sinks

Add to saturated NaCl—Sp. Gr. 1.36

PC PMMA

floats

sinks

PETE

PVC

Burn test result- yellow flame

Burn test result- green flame

Add to 25% NaCl Sp. Gr. 1.19

sinks floats

Fingerprints

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

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

Jack CairnsCO-Director National Science

Olympiad

Jcairnsc@aol.com

704 N. Bradford St.

Dover, DE 19904

302-734-4600