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Forensics Chapter 16

Terms in this set (57)

What is the decomposition of organic matter by heat?
Pyrolysis
Heat energy can ignite distant objects through the transmission of:
Electromagnetic energy
Many explosive must have their own source of:
Oxygen
Hydrocarbon accelerants can be detected by:
A portable detector (sniffer) and trained dogs.
A common classification system characterizes ignitable liquids based on their boiling point ranges and number of - molecules as light, medium, and heavy petroleum distillates.
Carbon
The minimum temperature at which fuel vapor will ignite is known as:
The ignition temperature
Examples of secondary explosives do NOT include:
Lead azide
Gasoline residues are best characterized by:
Gas chromatography
Which type of explosives detonate almost instantaneously to produce a smashing or shattering effect?
High explosives
What is radiation?
Transfer of heat energy from a heated surface to a cooler surface
Complex chromatographic accelerants patterns can be simplified by:
Mass spectrometry
Which of the following is a poor conductor of heat?
Wood, paper and plastic
All combustible fuel simultaneously igniting to engulf a structure in flames is known as:
Flashover
Which of the following statements is true?
Oxidations are chemical reactions that produce new substances.
Sinlge base smokeless power consists of:
Nitrocellulose
Telltale signs of arson include:
Separate points of origin, trails of burn patterns, and the presence of containers.
The transfer of heat energy by the movement of molecules within a liquid or gas is:
Convection
Movement of heat through a solid object is caused by:
Conduction
Most explosive can be recovered from debris for future study by being rinsed with:
Acetone
Which is NOT a high explosive?
Black powder
When investigators search a fore scene, the first focus must be on:
Finding the origin of the fire.
Which chemical reaction is associated with a fire?
Oxidation
The quantity of heat from a chemical reaction comes from:
The breaking and formation of chemical bonds.
The speed in a low explosive is called the speed of:
Deflagration
Which is often used as the explosive core in a detonating cord?
PETN
Which is a natural heat producing process that may give rise to a fire?
Spontaneous combustion
What is the minimum temperature at which a liquid fuel will produce enough vapor to burn?
Flash point
What is the concentration at which a vapor to fuel mixture in the air is capable of burning?
Flammable range
What is the major advantage of using the vapor concentration technique with gas chromatography?
High sensitivity for detecting volatile residues.
Which substance has the highest ignition temperature?
Benzene
Arson investigators must work quickly to collect evidence at a fore scene because:
Acclerants in soul may rapidly degrade, safety requirements may require that cleanup and salvage operation begin quickly, accelerants residues may quickly evaporate.
Which if the following statements is FALSE?
Dynamite is an initiating high explosive.
What is NOT true about primary explosives?
They are very stable.
Which is the most widely used low explosive?
Black powder and smokeless powder.
Which is an initiating explosive often used in detonators?
Lead azide
Materials that have electrons firmly attached to their molecules:
Are poor conductors of heats.
Which of the following CANNOT be determined from a laboratory examination of evidence recovered from an arson?
The brand name of gasoline used to start the fire
Which of the following is NOT a military explosive?
Nitroglycerin
A procedure commonly used as a screening test for explosive residues is:
Thin layer chromatography, color spot tests, and gas chromatography mass spectrometry.
The minimum temperature at which a fuel will spontaneously ignite is called:
The ignition temperature
High explosives can be classified as either - or - explosives.
Primary; secondary
Which is a homemade explosive that has been used by terrorist organizations in the Middle East?
TATP
Which is a chemical used to synthesize the explosive TATP?
Hydrogen peroxide
Explosives that decompose at relatively slow rates are classified as:
Low explosives
Which is a device used to screen objects for the presence of explosive residues?
Ion mobility spectrometry
What is the rapid combination of oxygen with a fuel, which produces a noticeable release of energy?
Combustion
Which type of screening and confirmation test are used for analyzing evidence of explosives?
Color spot tests, gas chromotography/mass spectrometry and TLC.
Which is an explosive readily detonated by heat or shock?
Primary explosive
Factors that can contribute to abnormal observations at a fire scene include:
Stairway or elevator shafts, wind or drafts, and secondary fires due to collapsing floors or roof.
Combustion occurring at the surface of a solid describes:
Glowing combustion
Which is available in commercial form as fertilizer?
Ammonium nitrate
A fuel can only achieve combustion in:
The gaseous state
Water being heated on a stove illustrates the concept of:
Convection
The likelihood that spontaneous combustion will occur in improperly ventilated containers of highly unsaturated oils is- the likelihood that such combustion will occur with hydrocarbon lubricating oils.
Greater than
Which instrumentation is considered the most sensitive and reliable for detecting and characterizing flammable residues?
Gas chromotography
Which are common chemical ingredients of black powder?
Potassium nitrate, charcoal, sulfur.
A low explosive has a velocity of detonation less than:
1000 meters per second.
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