The Chemistry of Fire
Fire is what type of chemical reaction?
oxidation reaction
What is the first step of a fire investigation?
locate the point of origin
What are the two most common type of accelerants?
Gasoline and kerosene
What is an example of a high explosive?
dynamite, TNT, ammonium nitrate-based explosives
For a homemade bomb, what helps to identify the person who created it?
The bomb will have specific characteristics or a "signature"
True or False: All oxidation reactions result in fire
False
True or False: When a fire scene is being cleaned up, it is too late to look for evidence
True
Why would a suspected arsonists' clothes be collected as evidence?
They may contain trace elements of accelerant
What is an example of a low explosive?
black powder, smokeless powder
For a bomb scene, what is the most important evidence to find?
detonating mechanism, other parts of bomb
oxygen, heat, fuel, chemical reaction
True or False: You must always obtain a search warrant before investigating a fire scene
False
Where could an investigator look for/collect evidence from a fire scene?
anything porous - cracks in floor, rags, upholstery, plaster
Primers and blast caps are considered what type of explosive?
low
What are two effects of a bomb?
flying debris, shrapnel, blast effect, expansion of gasses
What is it called when a fuel burns without a flame?
smoldering or glowing combustion
After origin has been determined, what is the next step of the investigation?
protect, sketch, photograph and take samples
How do we collect and store arson evidence?
In air-tight containers
What is used to set off secondary explosions?
primer or primary
What can be seen at the origin of the blast?
crater
What is an exothermic reaction?
a chemical reaction in which heat is given off
What does the origin of a fire look like?
The area closet to the lowest point that shows the most intense characteristics of burning
In the movie Backdraft, who was the arsonist?
Axe/Hancock
What are characteristics of a secondary explosion?
not as sensitive, longer reaction time, usually needs a primer
Individuals (not terrorist organizations)