Lecture 13 - Arson 1 Flashcards

1
Q

give 5 reasons why someone may commit arson

A

malicious intent
insurance fraud
attempt to harm someone
juvenile disorder
mental health or psychological problems

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2
Q

what might a fire be started with the intention of destroying

A

evidence of a different crime committed

fingerprint
DNA
fibres

mitochondrial DNA can actually withstand high temperatures

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3
Q

give three common setting of arsons

A

vehicles
dwelling
theft locations (burglaries)

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4
Q

what can help suggest if the death of a person was pre or post fire

A

CO in the lungs

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5
Q

what is one of the biggest causes of fires in the UK currently but what is low?

A

arson

the detection and conviction rates

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6
Q

what was the main aims of setting up the Arson control forum in 2001

how was the achieved

A

reducing arson related deaths, injuries and damage

by educating more people and giving better education
resources were spent in a targeted manner to cause maximum impact

the money spent looks like a lot but the money this save the UK on damage costs was massive

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7
Q

what 4 research areas did the Arson control forum dive into in aim to reduce arson incidents

A

the motivation of arsonists

links between arson and vehicle crime

social exclusion and fire risk

why arson prosecution fail

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8
Q

what has the arson control forum now been rebranded as

A

the Arson Prevention Forum

since 2013

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9
Q

recently has there been an increase or decrease in the amount of arson

A

increase

the only benefit to this is giving work to forensic investigators

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10
Q

in what 3 ways can a fire be considered accidental but still hold legal liability in a criminal proceeding

A

1 - infringement of safety regulations and legislation = unlicensed storage or unsuitable storage

2 - neglect and failure to employ duty of care = not doing safety checks properly

3 - fire caused as consequence of committing another crime = illegal bypass of gas metres

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11
Q

why is it beneficial to just put the mitigation procedures in place

A

the cost to implement them is much lower than the cost after a fire has occurred

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12
Q

what is a combustion

A

the process of burning

a chemical change (particularly oxidation) with the production of light and heat

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13
Q

what is a fire

A

a rapid, persistent, chemical change that releases heat and light and is accompanied by flame - particularly in the exothermic oxidation of a combustible substance

a fire is a continuous series of exothermic, oxidative reactions that involve the fuels present

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14
Q

what is the key difference between a fire and a combustion

A

the presence of a flame

a fire is a flaming combustion

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15
Q

what are the physics and chemistry definitions of a flame

A

1 = the zone of burning gases and fine suspended matter associated with rapid combustion - a hot glowing mass of burning vapour. the condition of active, blazing combustion

2 = a region in which chemical interaction between gases occurs, accompanied by the evolution of heat and light

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16
Q

what are the 3 components of the fire triangle

A

heat
oxygen
fuel

17
Q

how much heat is needed for a combustion to occur

A

enough to overcome the intitial activation energy

18
Q

how can a fire be prevented or extinguished

A

by removing one or more of the three components of the fire triangle

19
Q

what is required for a fire to start

A

a initial ignition soruce or spark

20
Q

what is needed for a fire to maintain and persist

A

a chemical chain reaction

21
Q

what type of process is a combustion - oxidation or reduction

A

oxidation

21
Q

what are the products of a complete combustion of a hydrocarbon fuel

A

carbon dioxide (gas) and water (liquid)

assumption is made that complete combustion occurs

22
Q

is an oxidation and exo or endothermic process

A

exothermic = heat energy is liberated

23
Q

what is the heat liberated in a combustion called

A

the heat of combustion or enthalpy of combustion at a constant pressure

24
Q

what conditions does the standard enthalpy of combustion refer to

A

standard conditions = temp 298K, 1atm pressure

25
Q

what is the oxidation number of a pure element

A

0

26
Q

what is the oxidation number of a charged species

A

its charge

27
Q

what is the oxidation number of the alkali metals

A

+1

28
Q

what is the oxidation number of group 2 metals (alkaline earth metals)

A

+2

29
Q

what is the oxidation number of a halogens

A

-1

30
Q

what is the oxidation number of hydrogen

A

+1 unless in a metal hydride = MHx where it is -1

31
Q

what is the oxidation number of oxygen

A

-2 unless in a peroxide O-O = -1

31
Q

what happens in a combustion where there is a limited oxygen supply

A

incomplete combustion occurs and carbon monoxide is produced = toxic and can undergo further combustion to CO2

32
Q

what is an impurity found in many fuels

A

sulphur

33
Q

what is the complete combustion product of sulphur

A

SO3 but SO2 is more commonly seen as the complete combustion is a very slow process