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Accelerant

any material used to start or sustain a fire

Combustion

rapid combination of oxygen with another substance, accompanied by the production off noticeable heat and light

Endothermic Reaction

a chemical transformation in which heat energy is absorbed from the surroundings

Energy

the ability/potential of a system or material to do work

exothermic reaction

a chemical transformation in which heat energy is liberated or given off

flammable range

the entire range of possible gas of vapor fuel concentrations in air that are capable of burning

flash point

the minimum temperature at which a liquid fuel produces enough vapor to burn

glowing combustion

combustion on the surface of a solid fuel in the absence of heat high enough to pyrolyze the fuel

heat of combustion

the heat given off during combustion

hydrocarbon

any compound consisting of only carbon and hydrogen

ignition temperature

the minimum temperature at which a fuel spontaneously ignites

Modus Operandi

an offenders pattern of operation

Oxidation

the combination of oxygen with other substances to produce new substances

pyrolysis

the decomposition of solid organic matter by heat

spontaneous combustion

a fire caused by a natural heat-producing process in the presence if sufficient air and fuel

What is oxidation?

the combination of oxygen with other substances to produce new substances

What is combustion? why is rusting not accompanied by it?

rapid combination of oxygen with another substance, accompanied by the production off noticeable heat and light; rusting is not accompanied because iron combines with oxygen too slowly to permit combustion

A fire will burn until either of which two components is exhausted

oxygen and fuel

name two factors that influence the speed of reaction of a fire

physical state and temperature

in what physical state must a fuel exist in order to produce combustion when it reacts with oxygen? Why must it be in this state?

gaseous' molecules collide frequently with one another enough to support a fire

what is pyrolysis? how does it produce fire?

the decomposition of solid organic matter by heat; the gaseous products of pyrolysis combine with oxygen to produce fire

define and give two examples of glowing combustion

combustion on the surface of a solid fuel in the absence of heat high enough to pyrolyze the fuel ; cigarette and red glow of hot charcoal

what three requirements must be satisfied to initiate and sustain combustion

1. fuel must be present
2. oxygen must be available in sufficient quantity to combine with the fuel
3. heat must be applied to initiate the combustion and sufficient heat must be generated to sustain the reaction

as a fire progresses toward what region does the heat created by combustion tend to move?

from a high temperature region to a low temperature region

list and define three mechanisms of heat transfer

conduction- movement of heat through a solid object
radiation- transfer of heat from a heated surface to a cooler surface by electromagnetic radiation
convection- transfer of heat energy by movement of molecules within a liquid or gas

what is an insulator?

material that is a poor conductor of heat

list three common signs of arson at a fire scene

1.presence of containers capable of holding an accelerant
2. discovery of a lighting device
3. irregular shaped burn patterns on the floor and ground

name three reasons why arson investigators must work quickly to collect evidence at a fire scene

1. accelerant residue evaporate within days/hours
2. safety- clean up needs to take place quickly
3. accelerants can quickly be degraded by bacterial action

what are streamers? what does evidence of their presence suggest?

they are accelerants like gas/paper that help fire spread rapidly. they suggest arson

why should fire evidence be packaged in airtight containers?

so possible residues are not lost through evaporation

what instrument do most criminalists consider the most sensitive and reliable for detection and characterizing flammable residue

gas chromatograph

what is headspace? how it is recovered?

vapors containing residue in the debris of a fire is heated and driven off and trapped in an airtight container's enclosed airspace ' its removed with a syringe

Burning methane for the purpose of heating water to produce stream in order to drive a turbine is an example of converting ___ energy to ____ energy?

chemical to mechanical

The quantity of heat evolved from a chemical reaction arises out of the ___ and ___ of chemical bonds

breaking and formation

Molecules must ____ energy to break their bonds and ____ energy when their bonds are reformed

absorb; give off

all oxidation reactions ___ heat

liberate or give off

the collection of debris at the origin of a fire should include all ____ materials

porous

____ 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 ____ of its gas chromatograph

pattern

can the criminalist identify gasoline residue by its brand name/

no

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