Dynamite and TNT - Periodic Table of Videos

I was once asked to hit nitroglycerin or sample of nitroglycerin with a hammer they pulled some out on a brick gave me the hammer said stroke it gently and I did and it went off with one hell of a bang so today I'm going to talk about a compound with recently we did one on the Nobel Prize and Alfred Nobel made his money from dynamite so I thought we'd do one on dynamite and nitroglycerine here is the active ingredient the explosive in dynamite it comes from glycerol which is a natural compound you just nitrate it and you get nitroglycerin which is a kind of oily heavy substance but it was found very quickly that it is very explosive and in fact it's dangerous to make Alfred Nobel's genius was to absorb it onto so-called dead earth and what you would do he found that if you put the dead earth on a sheet of paper and then you rolled that paper up like an arctic roll then it became an ice stick and you could transport these sticks and because it was absorbed onto that dead earth it gave a bit of shock resistance so he came he tamed it essentially by putting it into this stick and calling it dynamite and dynamite would you normally get in these sort of sausage shaped sticks it's really very stable you can throw it on the fire and it'll just burn and you need to use a detonator which produces a real shock wave which then travels down the stick forcing the explosion to take place I was once given a set of photographs which showed how this explosion travels down the stick in one ten thousandth of a second it's all over and it really looks very dramatic if you're clever you can focus the shock from an explosion rather like you can focus light with the lens and then you can do some really dramatic things so if you look at this piece of metal here it's really quite thick and I was shown what happens when you take hundred grams that's not really very much not much more than this bar of chocolate small bar of chocolate the salt you eat for lunch if you use that with the shape charge set it off here you can make a hole right through it you can see here my pencil go right through and you can see here there's the blast marks you can even still see 30 years on from when this was done a few traces of the copper casing of the detonator and on the other side you can see where the explosion burst out so that was a great explosive in it at the onset of the first world war this was being used a lot in mines and also in bombs but the problem with this compound is nitroglycerine it explodes very quickly so if you are trying to explode a bomb and destroy a building say this when it hits the outside of the building or a media explode what you really want is to get slightly inside the wall before you explode because then you're going to blow the wall apart much more effectively so another Nobel Prize winner Bader invented this compound and it's the Germans who invented this in the early 1900s and you'll know it as TNT so it made famous by cartoons and Acme TNT is trying nitro toluene so these are nitro groups here this blue is nitrogen the red is oxygen and the clever thing with both nitroglycerin in TNT is that in order to burn to make carbon dioxide nitrogen normally when we set light to things we need oxygen from the air to enable that to burn these have enough oxygens in here to make all these carbons turn into carbon dioxide that gas expands that's what makes the the explosion TNT was found to have a little initiation period it's probably not quite as explosive in absolute power terms as the nitroglycerin but the great thing about this molecule was that it would there'll be a tiny delay a fraction of a second delay before it exploded upon impact which meant that the missile could get partway through the bunker before it exploded and it created a lot more damage the mark 25 torpedo tube is severely damaged when it detonates the carbon reacts with an hydrogen react with the oxygen to make water and carbon dioxide and the nitrogen atoms combine to make n2 n2 has one of the strongest bonds between any two atoms and it's a triple bond between nitrogen and forming this bond releases a lot of heat so does the combination of carbon with oxygen and hydrogen with oxygen so in effect you get instantaneous burning there are all gases the gases expand this is a liquid so it's dense gases want to expand they're going to be very hot remember so they're going to want to expand that is actually the explosion it's that expansion and generation of gas in a confined space it wants to be much much bigger I work here in Nottingham and Nottingham has a special connection with TNT or more precisely a suburb of Nottingham called chill well because during the First World War chill well had the main depot the main factory where they filled the shells that were taken to the Western Front for all the guns TNT is bright yellow and the young women who worked filling the shells started absorbing it in their skin and were known as the - well Canaries because their skin was bright yellow and there's a book was recently published about these women working the shell factory called the canary girls of chill well and on the 1st of July 1918 there was an enormous explosion in the ammonium nitrate and TNT works nobody to this day notes quite why it happened but you can see the whole place was wrecked windows miles away were broken by the shockwave from the explosion and a large number of people probably more than 200 were killed there's still a monument to these people who died but at the time it was kept quite secret because it was in the middle of the war and within a few days production had restarted and they started filling the shells nitro compounds are useful because they call cause dilation of blood vessels so they're useful to give to people that have high blood pressure which puts a strain on their hearts because it expands the blood vessels and the heart can pump more easily in fact it's said that people who worked in nitroglycerin plants used to have to take samples of nitroglycerin on holiday with them to sniff so that their blood vessels didn't contract too much when they were on holiday and our famous lecturer from Nottingham Biddy Shaw who used to lectures on explosives most interestingly was treated for many years with nitroglycerin and it just seems quite amusing to me that an explosives specialist had his life prolonged by nitroglycerin treatment

Channel: Periodic Videos

Views: 1,458,357

Rating: 4.8840547 out of 5

Keywords: TNT, dynamite, nitroglycerin

Id: pWuYtvzxuLE

Length: 8min 57sec (537 seconds)

Published: Thu Feb 03 2011

Reddit Comments

[u/[deleted]]

4:20 - he claims TNT has enough oxygen to turn all the carbons into carbon dioxide. I'm pretty sure that's incorrect.