FRSC 2600-H02 EXAM #3: CH17-20 QUESTIONS
1. List three factors that make investigating arson and explosions particularly difficult for
forensic scientists.: Thoroughly planned out, perpetrator not present, extensive destruction
2. What physical state must a fuel occupy in order to produce a flame? Why can it
produce a flame only in this state?: a. Gaseous state
b. Molecules are in an excited state and spread apart.
3. Define and describe the process of pyrolysis.: Breakdown of a solid into a gaseous state so it can
be ignited.
4. Why is it important that the arson investigator begin examining a fire scene for signs
of arson as soon as the fire has been extinguished?: Evidence, like accelerant, can evaporate
5. What is the primary focus of a fire-scene search and why? What evidence at a fire
site may indicate the possibility of arson?: a. Used to help determine if accidental or arson, start at the
origin of the fire.
b. Evidence of separate and unconnected fires, use of "streamers", irregularly shaped pattern on the floor
6. Why might an investigator conduct laboratory tests on unburned control material
collected at a fire scene?: Comparison
7. Describe the headspace technique for recovering accelerate residues. What
instrument is most often used to detect and characterize recovered flammable residue?:
Heat an airtight container, use a pipette to collect some of the vapors, put into the GCMS to compare the vapors.
8. What are the primary explosives and what are they used for?: a. Ultra-sensitive to heat,
shock, or friction
b. Blasting caps, primers, used to detonate other explosives.
9. Name two types of low explosives?: a. Black powder
b. Smokeless powder
10. True or False: The absence of chemical residues always rules out the possi- bility of
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,arson.: False
11. The combination of oxygen with other substances to produce new chemical
products is calls .: oxidation
12. True or False: All oxidation reactions produce noticeable quantities of heat and
light.: False
13. is the capacity for doing work.: Energy
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, 14. Burning methane for the purpose of heating water to produce steam in or- der to
drive a turbine is an example of converting energy to
energy.: chemical
; mechanical
15. The quantity of heat evolved from a chemical reaction arises out of the
and of chemical bonds.: breaking ; formation
16. Molecules must (absorb, liberate) energy to break their bonds and (absorb,
liberate) energy when their bonds are reformed.: absorb ; liberate
17. All oxidation reactions (absorb, liberate) heat.: liberate
18. Reactions that liberate heat are said to be .: exothermic
19. Excess heat energy liberated by an oxidation reaction is called the .: he
20. A chemical reaction in which heat is absorbed from the surrounding is said to be
.: endothermic
21. True or False: All reactions require an energy input to start them.: False
22. The minimum temperature at which a fuel burns is known as the temp
23. A fuel achieves a sufficient reaction rate with oxygen to produce a flame only in the
(gaseous, liquid) state.: gaseous
24. The lowest temperature at which a liquid fuel produced enough vapor to burn is
the .: flash point
25. is the chemical breakdown of a soil material to gaseous products.: Pyrolysis
26. is a phenomenon in which a fuel burns without the presence of a flame.-
: Glowing combustion
27. The rate of a chemical reaction (increases, decreases) as the temperature rises.:
increases
28. described a fire caused by a natural heat-producing process.: Spontaneous
combustion
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1. List three factors that make investigating arson and explosions particularly difficult for
forensic scientists.: Thoroughly planned out, perpetrator not present, extensive destruction
2. What physical state must a fuel occupy in order to produce a flame? Why can it
produce a flame only in this state?: a. Gaseous state
b. Molecules are in an excited state and spread apart.
3. Define and describe the process of pyrolysis.: Breakdown of a solid into a gaseous state so it can
be ignited.
4. Why is it important that the arson investigator begin examining a fire scene for signs
of arson as soon as the fire has been extinguished?: Evidence, like accelerant, can evaporate
5. What is the primary focus of a fire-scene search and why? What evidence at a fire
site may indicate the possibility of arson?: a. Used to help determine if accidental or arson, start at the
origin of the fire.
b. Evidence of separate and unconnected fires, use of "streamers", irregularly shaped pattern on the floor
6. Why might an investigator conduct laboratory tests on unburned control material
collected at a fire scene?: Comparison
7. Describe the headspace technique for recovering accelerate residues. What
instrument is most often used to detect and characterize recovered flammable residue?:
Heat an airtight container, use a pipette to collect some of the vapors, put into the GCMS to compare the vapors.
8. What are the primary explosives and what are they used for?: a. Ultra-sensitive to heat,
shock, or friction
b. Blasting caps, primers, used to detonate other explosives.
9. Name two types of low explosives?: a. Black powder
b. Smokeless powder
10. True or False: The absence of chemical residues always rules out the possi- bility of
1/
16
,arson.: False
11. The combination of oxygen with other substances to produce new chemical
products is calls .: oxidation
12. True or False: All oxidation reactions produce noticeable quantities of heat and
light.: False
13. is the capacity for doing work.: Energy
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16
, 14. Burning methane for the purpose of heating water to produce steam in or- der to
drive a turbine is an example of converting energy to
energy.: chemical
; mechanical
15. The quantity of heat evolved from a chemical reaction arises out of the
and of chemical bonds.: breaking ; formation
16. Molecules must (absorb, liberate) energy to break their bonds and (absorb,
liberate) energy when their bonds are reformed.: absorb ; liberate
17. All oxidation reactions (absorb, liberate) heat.: liberate
18. Reactions that liberate heat are said to be .: exothermic
19. Excess heat energy liberated by an oxidation reaction is called the .: he
20. A chemical reaction in which heat is absorbed from the surrounding is said to be
.: endothermic
21. True or False: All reactions require an energy input to start them.: False
22. The minimum temperature at which a fuel burns is known as the temp
23. A fuel achieves a sufficient reaction rate with oxygen to produce a flame only in the
(gaseous, liquid) state.: gaseous
24. The lowest temperature at which a liquid fuel produced enough vapor to burn is
the .: flash point
25. is the chemical breakdown of a soil material to gaseous products.: Pyrolysis
26. is a phenomenon in which a fuel burns without the presence of a flame.-
: Glowing combustion
27. The rate of a chemical reaction (increases, decreases) as the temperature rises.:
increases
28. described a fire caused by a natural heat-producing process.: Spontaneous
combustion
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