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Fires and Explosions > Explosions > Flashcards

Explosions Flashcards

1
Q

What are the 3 examples of explosions with equations?

A
  1. Physical (pV = nRT)
  2. Nuclear (E = mc^2)
  3. Chemical (ΔG = ΔH – TΔS)
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2
Q

What is an explosive?

A
  • Energetic materials but not all explosions are caused by energetic materials
  • An energetic matertial contains its own oxident (doesnt need to rely on oxygen in air so is more efficient and powerful)
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3
Q

What is a primary explosive?

A
  • Sensitive to shock, heat, light, electricity
  • Easily detonated
  • Extremely dangerous to user
  • Not generally synthesised on a large scale because they can accidentally go off
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4
Q

What is a secondary explosive?

A
  • More difficult to detonate
  • Contact-insensitive
  • Typically detonated by a small amount of primary explosive - ‘blasting cap’/detonator
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5
Q

What are low explosives?

A
  • Typically deflagrate
  • They burn except when pressurised (when they can detonate)
  • Typically used as propellants
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6
Q

What are some examples of low explosives?

A
  • Gunpowder
  • Fuels (propane, methane, hydrogen)
  • Fireworks
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7
Q

What are high explosives?

A
  • Typically detonate
  • The chemcial reaction yields a supersonic shock wave
  • Tend to contain the oxidiser in one molecule
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8
Q

What are some examples of high explosives?

A
  • TNT
  • Nitroglycerin
  • RDX
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9
Q

What is deflagration?

A

A rapid oxidation reaction generating a low intensity pressure wave of moving gases
* Propagation of the reactions takes place at the surface of the material and is subsonic

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10
Q

What is the equation for the rate of burning (da/dt)?

A

da/dt = rA𝜌
* r = burn rate constant
* A = area
* 𝜌 = density

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11
Q

What is the equation for the burn rate constant (r)?

A

𝑟= 𝛽𝑃^𝛼
* 𝛽 = burn rate coefficent (constant)
* 𝑃 = pressure
* 𝛼 = pressure index (constant)

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12
Q

How do you cause deflagration to happen more quickly (detonation)?

A

Increase the surface area (powder) and pressure (confinement) to stop the gases from leaving

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13
Q

What is detonation?

A

A process of supersonic combustion in which a shock-wave is propagated forward due to energy release in a reaction zone behind it

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14
Q

Teritary Explosives

A
  • Very difficult to initiate
  • Usually need a secondary explosive to detonate
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15
Q

What are some examples of primary explosives?

A
  • Copper Azide, NitrogenTrihalides, Lead Azide, Silver Azide, Mercury Fulminate, Lead Styphnate
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16
Q

What are some examples of secondary explosives?

A

TNT, RDX/TNT, Amatol, RDX/Grease

17
Q

What is an example of a tertiary explosive?

A

Ammonium Nitrate

Fires and Explosions (20 decks)

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