CES Explosive Materials & Chemical Composition 3 — Questions and Answers
Question 1: Nitroglycerin (NG) is chemically unstable in pure form. What chemical process causes pure NG to degrade over time?
- Hydrolysis and acid decomposition, which lowers pH and accelerates self-decomposition (Correct answer)
- Polymerization into an inert gel
- Oxidation of nitrogen groups to nitrogen gas
- Crystallization at temperatures above 50°F
Correct answer: Hydrolysis and acid decomposition, which lowers pH and accelerates self-decomposition
Pure nitroglycerin slowly hydrolyzes, producing nitric and nitrous acids that catalyze further decomposition—this is why dynamite uses NG absorbed in diatom earth or other stabilizers.
Question 2: Which component of dynamite was Nobel's key innovation over pure nitroglycerin?
- Kieselguhr (diatomaceous earth) as an absorbent to stabilize liquid nitroglycerin (Correct answer)
- Addition of ammonium nitrate to reduce sensitivity
- Mixing TNT to balance oxygen content
- Use of PETN as a less sensitive base charge
Correct answer: Kieselguhr (diatomaceous earth) as an absorbent to stabilize liquid nitroglycerin
Nobel discovered that absorbing liquid nitroglycerin into kieselguhr (diatomaceous earth) produced a stable, handleable explosive that still detonated reliably with a blasting cap.
Question 3: In the context of explosive chemistry, what is 'brisance'?
- The shattering effect of an explosive, related to its detonation velocity and pressure (Correct answer)
- The total heat released per gram of explosive
- The sensitivity of an explosive to electrostatic discharge
- The rate at which an explosive deflagrates
Correct answer: The shattering effect of an explosive, related to its detonation velocity and pressure
Brisance describes the shattering or crushing effect of an explosive detonation, which is proportional to detonation pressure and velocity of detonation (VOD).
Question 4: Ammonium nitrate (AN) undergoes thermal decomposition at elevated temperatures. At approximately what temperature does AN begin to decompose dangerously?
- Above 230°C (446°F) (Correct answer)
- Above 100°C (212°F)
- Above 400°C (752°F)
- Above 50°C (122°F)
Correct answer: Above 230°C (446°F)
Ammonium nitrate decomposes more rapidly above 230°C and can undergo explosive decomposition, especially in confined conditions or in the presence of contaminants.
Question 5: What is the chemical formula for PETN (pentaerythritol tetranitrate)?
- C₅H₈N₄O₁₂ (Correct answer)
- C₃H₆N₆O₆
- C₇H₅N₃O₆
- C₂H₄N₂O₄
Correct answer: C₅H₈N₄O₁₂
PETN (C₅H₈N₄O₁₂) is a nitrate ester high explosive with one of the highest detonation velocities among common commercial explosives.
Question 6: When blasting agents are mixed on-site (bulk delivery), the critical parameter that determines whether the mixture is classified as an explosive is:
- Whether the final mixture can be detonated by a No. 8 test blasting cap (Correct answer)
- Whether the oxidizer exceeds 70% by weight
- Whether fuel oil content exceeds 6% by weight
- Whether the mixture meets DOT Class 1 density thresholds
Correct answer: Whether the final mixture can be detonated by a No. 8 test blasting cap
Under ATF regulations, a blasting agent is a material that cannot be detonated by a No. 8 test blasting cap and is classified separately from high explosives.
Question 7: What is the primary chemical reaction during the detonation of ANFO, and what are the ideal gaseous products?
- 3NH₄NO₃ + CH₂ → 3N₂ + CO₂ + 7H₂O, producing nitrogen, carbon dioxide, and water vapor (Correct answer)
- NH₄NO₃ → N₂O + 2H₂O, producing nitrous oxide and water
- 2NH₄NO₃ → 2N₂ + O₂ + 4H₂O, producing nitrogen, oxygen, and water
- NH₄NO₃ + C → NH₃ + CO₂ + H₂O, producing ammonia and carbon dioxide
Correct answer: 3NH₄NO₃ + CH₂ → 3N₂ + CO₂ + 7H₂O, producing nitrogen, carbon dioxide, and water vapor
The ideal ANFO detonation reaction (3NH₄NO₃ + CH₂ → 3N₂ + CO₂ + 7H₂O) yields nitrogen, carbon dioxide, and water when properly oxygen-balanced at the 94/6 AN/FO ratio.
CES Explosive Materials & Chemical Composition 3
Nitroglycerin (NG) is chemically unstable in pure form.
What chemical process causes pure NG to degrade over time?