Chapter 14 Fire Investigation Flashcards
Oxidation
The combination of oxygen with other substances to produce new substances
Modus operandi
An offender’s pattern of operation
Energy
The ability or potential of a system or material to do work.
Combustion
Rapid combination of oxygen with another substance, accompanied by production or noticeable heat and light
Exothermic reaction
A chemical transformation in which heat energy is liberated
Heat of combustion
The heat liberated during combustion
Endothermic reaction
A chemical transformation in which heat energy is absorbed from the surroundings
Ignition temperature
The minimum temperature at which a fuel spontaneously ignites
Flash point
The minimum temperature at which a liquid fuel produces enough vapor to burn
Pyrolysis
The decomposition of solid organic matter by heat
Flammable range
The entire range of possible gas or vapor fuel concentrations in air that are capable of burning
Glowing combustion
Combustion on the surface of a solid fuel in the absence of heat high enough to pyrolyze the fuel
Spontaneous combustion
A fire caused by a natural heat-producing process in the presence of sufficient air and fuel
Accelerant
Any material used to start or sustain a fire
Hydrocarbon
Any compound consisting of only carbon and hydrogen
Chemical equation for the burning of methane gas
CH_4 + 2O_2 —> CO_2 + 2H_2O
Methane + oxygen yields carbon dioxide + water
Chemical equation for rust
4Fe + 3O_2 —> 2Fe_2O_3
Iron + oxygen yields iron oxide
Conduction
Movement of heat through a solid object
Radiation
The transfer of heat energy from a heated surface to a cooler surface by electromagnetic radiation
Convection
The transfer of heat energy by movement of molecules withon liquid or gas
True or false: the absence of chemical residues always rules out the possibility of arson.
False
The combination of oxygen with other substances to produce new chemical products is called ___________.
Oxidation
True or false: all oxidation reactions produce noticeable quantities of heat and light.
False
________ is the capacity for doing work.
Energy
Burning methane for the purpose steam in order to drive a turbine is an example of converting _______ energy to ________ energy.
Absorb; liberate
Molecules must (absorb; liberate) energy to break their bonds and (absorb; liberate) energy to break their bonds are reformed.
Absorb; liberate
Reactions that liberate heat are said to be ______.
Exothermic
A chemical reaction in which heat is absorbed from the surroundings is said to be _______.
Endothermic
The minimum temperature at which fuel burns is known as the _________ temperature.
Ignition
The lowest temperature at which a liquid fuel process enough vapor to burn is the _______.
Flash point
__________ is phenomenon in which a fuel burns without the presence of a flame.
Glowing combustion
The lowest temperature at which a liquid fuel produces enough vapor to burn is the ________.
Flash point
__________ describes a fire caused by a natural heat-producing process.
Spontaneous combustion
Electrons and atoms within a solid object exposed to heat collide with one another, causing movement of heat through the object is called __________.
Conduction
In a process known as _______, a heated surface emits electromagnetic radiation of various wavelengths that moves in a straight line from one surface to another, helping the fire to spread throughout a structure.
Radiation
True or false: an immediate search of a fire scene can commerce without obtaining a search warrant.
True
True or false: the probable origin of a fire is most likely closest to the lowest point that shows the most intense characteristics of burning.
True
________ containers must be used to package all materials suspected of containing hydrocarbon residues.
Airtight
The identity of a volatile petroleum residue is determined by the (size; pattern) of its gas chromatogram.
Pattern
True or false: a forensic analyst typically compares the gas chromatographic pattern generated from a fire-scene sample to a library of patterns in order to identify the accelerant.
True
Complex chromatographic patterns can be simplified by passing the continents emerging from the gas chromatographic column through a(n) _______.
Mass spectrometer
Indicate which method of heat transfer is most likely to be responsible for each:
A. Ignition of papers in the room where a fire starts
B. ignition of electrical wiring in a room adjoining the fire’s point or origin.
C. Ignition of roof timbers
D. Ignition of a neighboring house
A. Radiation
B. conduction
C. Convection
D. Radiation
