Arson/Explosives

Question 1

A shock wave is produced when:

Answer 1

A wave front exceeds the speed of sound

Question 2

A sudden, rapid, and often violent release of hot expanding gases is called

Answer 2

an explosive (explosion??)

Question 3

All of these can be used to initiate an IED except:

Answer 3

TNT

Question 4

Deflagration is an oxidative decomposition in which the propagation speed is ____ than the speed of sound

Answer 4

slower

Question 5

What determines how much residue of an accelerant will be left and for how long?

Answer 5

How volatile the accelerant is

Question 6

What is the flash point?

Answer 6

The lowest temperature at which a liquid will produce enough vapor to burn

Question 7

What is the most common instrument used in fire and explosive analysis?

Answer 7

GC/MS

Question 8

What is the most common container used to collect fire debris evidence?

Answer 8

unlined paint can

Question 9

When collecting charred samples from the point of origin to help determine which type of accelerant used, what is also important to collect?

Answer 9

control samples

Question 10

Accelerants

Answer 10

any substance that is used to start or sustain a fire

Question 11

Accelerants are

Answer 11

easily vaporized, highly exothermic, and support combustion

Question 12

To initiate and sustain a fire, the following are required:

Answer 12

A fuel (vapor) must be present.
Oxygen must be available in sufficient quantity to combine with the fuel.
Heat must be applied to initiate the combustion, and sufficient heat must be generated to sustain the reaction

Question 13

Fire has a tendency to move _____

Answer 13

upwards

Question 14

If an arson is suspected then _______ need to be collected from around the point of origin

Answer 14

about two to three quarts of the ash and soot debris

Question 15

Neat, ignitable liquids

Answer 15

unburned accelerant residue

Question 16

Headspace method

Answer 16

the evidence container is generally heated, vapor above the matrix or the headspace can then be sampled with a gas-tight syringe and injected into the gas chromatograph

Question 17

Adsorption method

Answer 17

relies on the use of charcoal or Tenax®, a polymer resin used to trap volatiles and semi-volatiles

Question 18

Solvent extraction

Answer 18

The evidence container is opened and a small amount of a solvent is added

Question 19

Steam distillation

Answer 19

accelerant residue and water are steamed and distilled, the steam will heat and carry over accelerant residues

Question 20

One method of making illicit methamphetamine is called “shake and bake”. During the process, bottles like the one shown become hot enough to start fires. What is our source of ignition energy?

Answer 20

exothermic chemical reaction

Question 21

What is the purpose of headspace analysis in fire evidence?

Answer 21

It helps eliminate background noise from the burned debris

Question 22

Low explosives

Answer 22

deflagrating and only detonate when confined

Question 23

High explosives

Answer 23

insensitive but stable, require an initiator to detonate

Question 24

Primary explosives

Answer 24

Explosives that are ultra-sensitive to heat, shock, or friction

Question 25

Secondary explosives

Answer 25

Explosives that are relatively insensitive to heat, shock, or friction

Question 26

You inflate a balloon until it ruptures. This release of energy would be classified as

Answer 26

Explosion

Question 27

Identify the common secondary explosives

Answer 27

TNT
ANFO
Semtex

Question 28

The primary challenge of explosives analysis is

Answer 28

The device and its residues are often very difficult to locate

Question 29

Which method provides the fastest, easiest method of explosives residues identification, even if it is somewhat susceptible to false positives?

Answer 29

Ion Mobility Spectronomy

Question 30

Autoignition Temperature

Answer 30

Spontaneous ignition

Question 31

All fires have

Answer 31

point of origin and means of ignition

Question 32

What do we use to determine the point of origin?

Answer 32

“V” pattern
Low position
Deep charring
Near source of ignition energy

Question 33

Spark

Answer 33

electrical discharge

Question 34

Types of heat (ignition energy)

Answer 34

Radiation
Electrical resistance
Non-combustion exothermy
Friction

Question 35

Ignitable Liquids

Answer 35

Liquid fuel with a low flash point; highly exothermic

Question 36

Common Ignitable Liquids

Answer 36

Kerosene
Diesel
Gasoline
Coleman Fuel
Ethyl Alcohol
Isopropyl

Question 37

Incendiary

Answer 37

Deliberate ignition

Question 38

Deflagration

Answer 38

combustion through subsonic heat transfer

Question 39

Detonation

Answer 39

combustion through supersonic pressure front

Question 40

Explosion

Answer 40

rapid, expansive release of stored energy producing a shock wave

Question 41

Combustion

Answer 41

oxidation producing gas, heat, and/or light

Question 42

Secondary Explosives

Answer 42

Detonate in response to supersonic pressure wave

Question 43

Backdraft

Answer 43

Eruption of fire caused by oxygen rushing back into an engulfed room

Question 44

Convection

Answer 44

transfer of heat by a circulating medium, usually air or liquid

Question 45

Pyrolysis Zone

Answer 45

zone where the components of the wax are driven into the gas phase and start to degrade