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Forensics- Chapter 16

Terms in this set (44)

The combination of oxygen with other substances to produce new chemical products is called ____________
oxidation
T/F: All oxidation reactions yield carbon dioxide and water as products.
False
____________ is the capacity for doing work
energy
Burning methane to heat water and thus producing steam for the purpose of driving a turbine is an example of converting ________ energy to __________ energy to __________ energy
chemical; heat; mechanical
The quantity of heat evolved from a chemical reaction arises out of the __________ and __________ of chemical bonds.
breaking; formation
Molecules must __________ energy to break their bonds and ___________ energy when their bonds are re-formed.
absorb; liberate
Excess heat energy liberated by an oxidation reaction is called the _____.
heat of combustion
T/F: All reactions require an energy input to start them
True
The minimum temperature at which a fuel burns is known as the ____ temperature.
ignition
A fuel achieves a sufficient reaction rate with oxygen to produce a flame only in the _________ state.
gaseous
The lowest temperature at which a liquid fuel produces enough vapor to burn is the ____________
flash point
___________ is the chemical breakdown of solid material to gaseous products.
pyrolysis
The _________ defines the upper and lower limits between which a mixture of gaseous fuel and air burns.
flammable range
_________ is a phenomenon in which a fuel burns without the presence of a flame.
glowing combustion
T/F: The rate of a chemical reaction increase as the temperature rises.
True
______________ describes a fire caused by a natural heat producing process in a poorly ventilated area.
spontaneous combustion
T/F: An immediate search of a fire scene can commence without obtaining a search warrant
True
A search of the fire scene must focus on finding the fire's ____________.
origin
T/F: The origin of a fire is most likely to be located closest to the lowest point that shows the most intense characteristics of burning.
True
A portable __________ detector can suck in the air surrounding a questioned sample to rapidly screen for the presence of volatile residues at fire scenes.
vapor
T/F: The collection of debris at the origin of a fire should include all nonporous materials.
False
_________ containers must be used to package all materials suspected of containing hydrocarbon residues.
airtight
T/F: Substrate controls should be collected at a fire scene from an area where it can be reasonably assumed that no flammable substance was placed.
True
A(n) ________ is a mechanism consisting of a glass bottle containing flammable liquid with a cloth rag stuffed into it and lit as a fuse.
Molotov cocktail
The simplest way to recover accelerant residues from fire scene debris for identification is to heat the air tight container in which the sample is packaged and remove the ________ with a syringe.
headspace
The most sensitive and reliable instrument for detecting a characterizing flammable residues is the ______________.
gas chromatograph
Complex chromatographic patterns can be simplified by passing the components emerging from the gas chromatographic column through a(n) ___________
mass spectrometer
Rapid combustion accompanied by the creation of large volumes of gases describes a ________________.
explosion
T/F: Chemicals that supply oxygen are known as oxidizing agents
True
Explosives that decompose at relatively slow rates are classified as ______ explosives.
low
The speed at which low explosives decompose is called the speed of _____.
deflagration (burning)
Three ingredients of black powder are _______, _______, and _______.
potassium nitrate; Charcoal; sulfur
_________ explosives detonate almost instantaneously to produce a smashing or shattering effects.
high
The most widely used low explosives are __________ and ____________
black powder; smokeless powder
A low explosive becomes explosive and lethal only when it is _____________
confined
T/F: Air and a gaseous fuel burn when mixed in any proportions
False
High explosives can be classified as either ________ or ________ explosives.
primary (sensitive to heat & used to detonate other explosives through chain reaction primers) or secondary (insensitive to heat &burn rather than detonate)
The most widely used explosive in the military is ___________
RDX
The explosive core in detonating cord is ___________
PETN/ primacord
A high explosive is normally detonated by a(n) ____________ explosive contained within a blasting cap.
initiation
An obvious characteristic of a high explosive is the presence of a __________ at the origin of the blast.
crater
To screen objects for the presence of explosive residues in the field or the lab, the investigator may use a handheld __________.
ion mobility spectrometer
Unconsumed explosive residues may be detected in the laboratory through a careful _____ examination of the debris.
microscopic
T/F: Debris and articles at an explosion scene that are collected from different areas are to be packaged in separate airtight containers
True
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