Exam 17: Forensic Aspects of Fire and Explosion Investigation

Which is an explosive readily detonated by heat or shock?

Bombs made of high explosives must be detonated by an initiating explosion.

A large container of gasoline is recovered from the walk-in freezer at a restaurant owned by an arson suspect. The gasoline temperature is found to be -10 degrees Fahrenheit. The suspect claims this gasoline would be too cold to have been used as an accelerant in the arson. Describe the difference between flash point and ignition temperature and use this information to explain whether the suspect's claim is true or untrue.

Gasoline residues are best characterized by:

Factors that can contribute to abnormal observations at a fire scene include:

Match the word in Column 1 to its definition in Column 2. Each answer can only be used once. A)The entire range of possible gas or vapor fuel concentrations in air that are capable of burning B)Any material used to start or sustain a fire C)The decomposition of solid organic matter by heat D)The minimum temperature at which a fuel spontaneously ignites E)A chemical transformation in which heat energy is liberated F)Any compound consisting of only carbon and hydrogen G)A chemical transformation in which heat is absorbed from the surroundings H)The combination of oxygen with other substances to produce new substances I)The ability or potential of a system or material to do work J)Combustion on the surface of a solid fuel in the absence of heat high enough to pyrolyze the fuel K)Rapid combination of oxygen with another substance, accompanied by production of noticeable heat and light L)An offender's pattern of operation M)A fire caused by a natural heat-producing process in the presence of sufficient air and fuel N)The minimum temperature at which a liquid fuel produces enough vapor to burn O)The heat liberated during combustion -Energy

________ is the combination of oxygen with other substances to produce new substances.

A fuel must be in its gaseous state to produce combustion when it reacts with oxygen.

Following microscopic examination, the recovered debris is thoroughly rinsed with ________.

Single-base smokeless powder consists of:

Nitroglycerin-based dynamite has virtually disappeared from the industrial explosives market.

Warm air expands, which causes it to become ________ dense.

Complex chromatographic accelerant patterns can be simplified by:

What are the two classes of high explosives? What is the difference between the two classes?

In a fire scene the electromagnetic radiation moves in a(n)________ line from one surface to another.

A bottle of gasoline sitting at room temperature does not spontaneously burst into flame, and yet gasoline is an excellent fire accelerant. Based on your knowledge of the chemical reactions that initiate and sustain fire, what needs to happen to that gasoline in order for it to burst into flame?

Criminalist Matt Hughes arrives at the scene of an explosion. He first carries out a search of the periphery of the crime scene, questions several witnesses, and then locates the crater caused by the blast. After finding the crater, he uses a sifter to separate the debris at the site for evidence. Any large pieces of detonators or foreign materials that did not fall through the mesh are collected and packaged in small paper bags. Large, jagged pieces found in the crater are wrapped in paper then placed in another paper bag. What mistakes, if any, did Matt make in collecting and storing this evidence?

________ is the chemical breakdown of solid organic matter by heat.

________ are trails of flammable material, such as gasoline or paper, spreading outward from a fire's point of origin in order to cause the fire to move rapidly from one room to another.

What is the concentration at which a vapor-to-fuel mixture in the air is capable of burning?