What is black powder used for?
it is a type of gunpowder used to accelerate small things very fast
What are some peaceful uses for explosives?
- Mining / Quarrying
- To increase efficiency
- Excavation (for construction)
- To make some space
- Cladding (explosion welding)
- Forensic Investigations
- Research
What is the deflagration process for the gunpowder invented in China around 142 AD
10 KNO3 + 3 S + 8 C → 2 K2CO3 + 3 K2SO4 + 6 CO2 + 5 N2
What was the problem with the gunpowder invented in 142 AD in China?
There would be residual carbon which isn’t always consumed so there’s black powder left over.
What components were used in traditional gunpowder?
- Potassium Nitrate
- Sulfur
- Carbon
What is carbon usually used for?
Fuel
What is KNO3 usually used for?
It contains oxygen so it’s likely a good oxidizer
If an element/compound decreases in oxidation state is it an oxidizer or fuel?
It’s likely a fuel
Black Powder
Generally deflagrates incompletely
Gun cotton
- Made of nitrocellulose
- Low explosive so it deflagrates
- It’s still used in firearms today
How effective is nitrocellulose?
It deflagrates very effectively
How is nitrocellulose formed?
- Nitric acid is added to cellulose
- Nitric acid to add nitro groups is common in explosive chemistry
- Nitration of cellulose is very effective
How was black powder made more dangerous in the early 1800’s?
- Exploding shells that contained gunpowder and had fuses were created
- This meant the black powder was enclosed and subjected to a higher pressure making the detonation more likely.
- This led to the development of exploding shells for modern artillery
What was the first commonly used high explosive?
Picric acid
What’s the problem with heavy metal salts?
- They are very unstable
- This is why Fe (Iron) shells are used over Pb (lead) but there are still very sensitive to shock
What’s the advantage of using picric acid?
- It is mostly stable
- As it relies on a phenol base, it is readily available due to the coal industry
How is picric acid created?
- A phenol is treated with nitric acid in the presence of another strong acid (Sulfuric acid for example).
- This is done as we need to generate an effective electrophile to get the nitro groups
What was TNT originally invented as?
Yellow dye in 1863
What’s the benefit of TNT?
It’s much more stable compared to picric acid and almost impossible to prematurely detonate which is preferable.
How can we reduce the activation energy?
If we can make stable intermediates this it will reduce the activation energy, this is to do with the ability to push around electrons
What are lone pairs good for?
Lone pairs are good for detonating into the ring?
What is RDX synthesised from?
Ammonia and formaldehyde
What does high brisance mean?
A good shattering power that is able to get through tanks and penetrate armour
What brisance does RDX/HMX have?
High brisance
