The Chemistry of Fire and Gunpowder - with Andrew Szydlo

The Chemistry of Fire and Gunpowder - with Andrew Szydlo

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00:05
[Music] [Applause] when I was a young lad when I was the young lad I used to belong to the Boy Scouts and every summer one of the highlights of my holidays was to go on a scout camp one of the greatest challenges for the young Scouts was to see how few matches they could use to light a campfire or a
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bonfire if you could use two or three matches to light a bonfire you're considered to be an expert if you could use just one match you were considered to be a grandmaster I used to use no matches now the campfire the bonfire which we have burning here this evening of course is part of an ancient human tradition the indeed our ability to make fire at our own will etc we're using our own
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techniques is one of the greatest achievements of early human civilization ten thousand fifty thousand years ago certainly a very very long time ago and today of course I wanted to talk about the primarily the chemistry of how the fires wood fires burn but also about the physics and the sociology so I'm going to start off by telling you that when wood burns it's actually when you're
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lighting fire and burning wood you are actually not burning the wood that is going to be the whole point of my demonstration this evening and I wanted to start off by showing you how it is possible to ignite I have here a propane burner and how we ignite a propane burner oh by the way before we go on I do have something I wanted to do and that's just to and ignite one of my I have a little spirit burner here and I'll tell you about why I'm igniting
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this because it's very very relevant to our topic so I'm just going to put that flame there and that I wanted to tell you that when we going back to a modern gas burner like this you see it's very easy to set the gas on fire and the reason is you press a little figure you can all see a little tiny little piezoelectric spark so if you want to set this on fire you simply turn on your your flow of gas here press this fart and bingo we have a wonderful flame and it's a light straightaway you see and we know that the propane is
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burning directly because it has come there however if I wanted to show you now I'm going to set fire to this piece of wood and if I hold this wood in out let's say flame here you can see the wood is not catching fire and furthermore you can probably understand that if I wanted this wood to catch fire it would take a very very long time indeed and the reason why this is the case it hasn't even just started to char the reason why it takes so very long indeed because actually the wood
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chemically changes into a whole range of different substances when it's actually burns and this is what I'm going to demonstrate for you today I'm going to start off by showing you I have here some sawdust sawdust is basically small pieces of tiny tiny pieces of wood they have a large surface area you can see they're smouldering a little bit as I drop them onto our fire which is burning so this is wood which has been pounded to a very very high level and I've
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placed it in his retort flask here now our retort flask is one of the most ancient pieces of apparatus chemical apparatus that the human being has invented and I'm going to in it is used primarily for heating a substance and then collecting any vapors that might come off from that substance and so what I'm going to do now is to heat this up this wood in here and let's see it's as if it catches fire inside the flask I'm
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going to heat it with a very very strong flavour indeed so allow me to turn the gas on turn on our thing here and I will now commence this process now this experiment which I'm going to demonstrate this process which I am demonstrating for you now is going to take a proxy ten minutes it's quite a long process and we're going to observe the gradual changes that take place to the ward as it is being roasted by my very very hot flame now I hope you can already see
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that there is a little bit of steam condensate collecting on the in inside on the top of the flask and indeed you can all now see that there is some smoke coming out of the bottom of the flask furthermore you can now see more slope and then those of you who can see there is some charring of the of the wood etc but and you can also probably see that the floss is glowing red-hot and yet the
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wood inside is not catching fire there children let's see now we'll carry on this heating process and we'll explain to you a little bit about what what would actually is made of I'm sure you will all agree that this very I'm going to put a light here to see Oh can you see that it's burning now that's not the wood it's burning it is actually a product of this chemical reaction which I'm doing here which I'm undertaking
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here and also you see that not only is that gas burning there but there is also a liquid dripping out of the bottom of the flask now if you don't mind I'm going to come round and with my back to you just to warm this up a little bit from the front please excuse me and I'm sure you'll all agree that we are now burning with the wood is not burning directly but it has been chemically changed into different substances and those different
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substances are now in the form of two different states of matter there is a gas which is being produced here in the form of a smoke and furthermore there is a liquid an orange and orange gooey smelly liquid which is coming out of the bottom furthermore you may observe that there is on the side of the flask a dark brown dark brown oily liquid which is going down the side of the
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flask so what I'm demonstrating for you is a type of a chemical reaction in which we take the wood which is made off I'll tell you very shortly what it's made of and we are breaking it down into smaller particles I'll just see we could get that to light again it burns sometimes sometimes it doesn't burn but the point is the wood is being chemically changed and I wanted to tell you in this very crude type of experiment and can I also tell you this
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type of experiment has been done for thousands of years not because people wanted to see what happens because it had a utilitarian purpose and that was to make charcoal you will notice already at the bottom of this flask that we have essentially a black solid which is in fact charcoal I am now going to try and set fire to it once again excuse me while I do wander around a little bit and many of you will be able to see the
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tar the sort of whoops-a-daisy these splints are not very good I tried to get one out I'm multitasking as you can see a reasonably successfully if I may say so now let's just put this this and let's put this myth I do love these fires out you must excuse me I'm a little bit I remain a cart I'm just trying to get enough of the products to be able to explain to you what is actually taking what is actually going on now you see there it is and I think
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that basically that's enough to show you that would when strongly heated it can change I'm going to turn off my flame now whoops-a-daisy let's get it turning in the right direction I think I've got it in the right direction yes that's turned it off now please look at this splendid the wood is producing a dense smoke and it is producing a liquid there so wood here is a solid we're talking about the states of matter here it is like this and we have heated it
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very strongly now that heating process is the same heating process of course when we put a splint into a flame and it catches fire instantaneously well not quite instantaneously because before it catches fire it always must char it must have a little bit of blackness on it a little bit of black charcoal and once it's got a bit of black charcoal we're then in the position what we're actually doing we're producing this smoky stuff here which is in the gas
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phase and we're producing this very very very smelly liquid here which can you see it's an oily car it's got some dark oily droplets in it and this is and it's suspended in a sort of a light orange type of watery layer and we have furthermore left behind here some charcoal so what we have done by applying the process of heat we have converted wood which is a solid into three completely different substances
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one of them is at three different states of matter should I say three states of matter one of them is a gas one of them is a liquid and one of them is a solid and each of those three states of matter is no longer the same as the wood which it started off as as I told you this process has been practiced for many many thousands of years primarily to make charcoal which I'll be talking about later but also to make this liquid here
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which is called a pyro ligneous distillates distillate because this retort flask here has collected the vapors and condensed them pyro meaning fire and ligneous derived from wood so we have a pyro ligneous distillate here and we have the gaseous mixture there and the charcoal over there now what I wanted to tell you next is in this very simple cruel experiment since this very crude experiment has been done and people have
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found use not only for the charcoal but for the gases and for the liquids as well chemists have made great advances and have been able to do this type of experiment and actually analyze the products in much much greater detail and what they have set up here is that their paratus for doing precisely this in this apparatus here I have in here in this round bottom flask here I have exactly
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the same material I have a pile of sawdust but this time rather than crudely allowing the gas mixture because it is actually a mixture of substances coming out there in terms of such States this is a solid this was a gas and this is a liquid in terms of chemistry though this is a mixture this is a mixture and that too is a mixture and I'll be explaining that because here using this apparatus we are actually going to
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separate some of the components of that mixture and I'm going to invite I have two assistants with me in order to carry out this experiment because this will take about 15 to 20 minutes and I will ask undressed to come on hundredths with Yakov is the senior laboratory technician and chemical demonstrators from Paul's School in West London and my son Oscar who is going to assist in the experiment today now I'm going to ask Andres and Oscar to commence this
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experiment here and I will explain the chemistry and the science of wood as they do so now for this purpose we're going to use a quite a strong propane a torture a propane torch with a significantly bigger flame and it should generate a reasonable result now on this occasion rather than just allowing the vapors here to be separated into a liquid and a gas
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we're going to pass the vapors first of all through a threshold bottle here which I have this is a type of bottle for collecting distilled vapors and condensing them and it's sitting in a beaker full of ice well that will enable to happen is that the vapors will start cooling down condensing much more efficiently than here this is a threshold bottle which contains sodium hydroxide solution now the sodium hydroxide solution here will
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chemically absorb one of the gases which is being produced in this process and the gas which is being produced in this throat it's a mixture of gases and carbon dioxide is one of them I think we can start collecting Oskar probably okay now the reason why I'm going to be giving a little bit of Direction is because this is not at all an easy experiment and the mixture of gases I am telling you straight away it's not one gas which comes off but it's a mixture of gases not too strongly out there just
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a little bit gently don't collect all the gases Oscar I'm giving a commentary there about 30 gas jars will be collected Oscar will only collect 5 of them and the reason is we want to show you how the composition of the gas changes as the process of pyrolysis continues now their children are one word I wanted you to learn today is what's happening here this experiment or what we're doing here breaking down a substance by the action of heat is
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called pyrolysis and it is a word which used to describe this process of breaking down wood into simpler substances now the one of the gases coming off is carbon dioxide some steam is produced as well but in those jars will be collected a mixture of three main gases which are produced which were all burning here and I'll tell you what those three main gases are they are carbon monoxide hydrogen and methane I
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will put this up on a screen for you later on and I will demonstrate each of these gases individually now while this reaction is taking place I will tell you a little bit about what would actually is made of and we can consider wood from two directions one from the points of chemistry what chemicals is it made of and I'm sure you'll agree that this is not one substance it's a mixture of lots of substances which have been produced
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by nature it's a mixture of substances and they are essentially natural polymers very very large molecules one of them is called cellulose it's the same molecule that you find in cotton wool in paper and wood and indeed it is one of the main molecules that is found in all plants another group of molecules are called hemicelluloses and the third type of molecule in water are called lignans now I will very briefly explain three types of molecule
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cellulose is our hydrocarbon carbohydrates which are polysaccharides they're made up of lots of sugar molecules which are produced in the plant and they join together to form the structure of the cells in the wood hemi cellulose and they're very organized cellulose is has is very strong in tension and they're long and they are they are arranged quite regularly in the structure of the wood Hemi semi loza's
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as the name suggests a much shorter molecules they are composed of different types of sugars and they're slightly more haphazardly arranged but they are necessary and they contribute to the structure of the wood and the lignin is the main type of material which is only found in wood and not in other plants which don't contain the wood the lignin is the wood enos of the plant now lignin is a most fascinating mixture of substances and the difference between
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lignin and the cart the cellulose and the Hemi semi roses is that lignin has lots of aromatic groups in it it's a different type of chemistry lignin is strong in compression and it gives wood that very very hard that the relative hardness with which we associate wood and I will be coming back to these terms because understanding what we have at the start will help us to understand to identify and discuss the products which
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are made at the end now how are we getting on MIDI on this it's how many how many jars will be got so far it's okay thank you very much indeed so we are going to explain to you also what the substances are a little bit about them before we continue further oh I know while that's actually going on I wanted just to tell you a little bit because this will take another couple of minutes a little bit about my own favorite Ward's I have two words which are my
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favorites one of them is balsa wood which is the wood out of which these models are made of and the reason why I like it so much is because it is the lightest it has the lowest density of all the woods in the whole world the density of balsa wood is naught point three grams per centimeter cubed now because it has such a very very low density it is fantastic for making models with etc and I wanted to show you by the way I bought a question which
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someone might come and tell me the answer to did you know their children that there is a metal which exists which has the same very low density as a balsa wood this is supremely light you will not meet this metal on an everyday basis but if anyone can come and tell me at the end of the lecture which metal has the same density as balsa wood he will receive or she will receive a prize from
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me the person preferably someone of the younger age group please now may I return that may I return although I suspect it might be a challenging question for non-specialists as well now what I wanted to show you is just simply how my own interest is I've got two models as you can see here made out of balsa wood this you see is is a boat made out of balls I made this when I was 8 years old in 1958 and I used to sell it I used to sort of I haven't an outboard motor and a little celluloid
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window and I used to sort of sail it in the paddling pool in Hammersmith Park close to where I used to live I regretted sometimes hit the bottom and in there hole so I put patches on it but because I spent so much time making it I could never bear the thought of throwing it away and that's why I brought it here now I used to make lots of model aeroplanes lots of model airplanes regrettably they all crashed on their first or second flight so it was a lot of time etc but one has survived and I brought this to show you
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here it's not in very good condition but it is made of balsa well it's an it's a control line you sort of put it all you have a motor you come here now like this and it flies around a long long things with a motor on it now the only reason why I've still got this is of course because it's the only one which didn't crash but the reason why I didn't crash because it never flew so that's why I said I actually couldn't get the engine to work I was a disaster now uhm Oscar would you be able have you almost finished the jars yeah Oscar's actually just just wanted to
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show you dear children it's such fun making these little balls they're very cheap you can buy them Oscar could you just demonstrate that you demonstrate this I'll collect the last year just give it a few throws that we must entertain ourselves children even so this is a little bit of error error error dynamics a little bit of aeronautical a baby fly has it flown Oscar thank you very much thank you Andres this is brilliant I have now collected the last jar now another another one of my favorite towards another one of my favorite
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towards please excuse me do we have some tissue oh yes we do have by the way I have to tell you secretly under here we have many useful things so I've got tissue we've got rubbish bins all sorts of things this really looks very very beautiful on this I think we have a fantastic result here and as you see 1d whence the heating has stopped the the products will start to cool down and very shortly we'll be able to analyse but I just wanted to tell you about another one of my favourite woods and I'll tell you why it's his maple I'll tell you why the
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maple is and one of my favorite wood well because first of all is because you can actually drink it it's one of the few trees one of the few trees where you can get a product from the woody substance of the tree and this is here maple syrup and I'm sure you all enjoy maple syrup but not sorry can you eat maple but you can also make splendid musical instruments from them and I would like to this demonstrate for you I have a musical instrument because I love music and I want to just to show
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you such an example of of playing a tune thank you very much Oskar on this is a viola and it's made of maple so we have wood we don't necessarily have them to burn wood all the time back in melody [Music]
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now you see that's a very straight that's a very straightforward melody see but the honest truth is so a little sociology my dear children is that of course when people used to meet at campfires and bonfires and things to play they used to meet in large groups you see and they used to talk and make food etc and they music was not only made by just one person necessarily but groups of people used to gather and I just invited a few of my friends with
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maple instruments to come and play you a Rumanian folk melody so if we can just come on where are their will
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[Music]
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so there we are just a little music thank you very much to my friends my Romanian friends as you see wood doesn't always have to be burnt as you know there are thousands of uses and now let's wrap it they return back to chemistry thank you very much Oscar let's return to the chemistry thank you so much there Andres is absolutely wonderful now what's happened unless we in the meantime we've had a sock back not to worry we shall that we show that that's unfortunately some water got sucked by
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we got carried away with the music and in fact it's gone right back into the flask now this by the way does show some very interesting principles of physics dear children we continue to learn when you heat gases they expand but will you allow them to cool they contract and what we've have happened here is as we went took our through the eyes of the of the equipment VM the water as the flask cool down water got sucked back from here into here into there and into there and I'm going to show you in other experiments at the end which shows you
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this exact phenomenon with some very very nice color changes but so what we've done is we fill the flask but not to worry we have collected our gases here we have also kept just in case this happened today I have a sample of what is known as the pyro ligneous distillate here and what I wanted to do is to explain to you a little bit about these substance which is we have here and I'm going to start off by telling you that the charcoal which I have here which we have a small Oscar could you sprinkle
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some charcoal this is the sprinkled some charcoal into the flame this is from a previous experiment I said we'd have kept supplies because we are ready for all sorts of circumstances and the most important thing is not to have an accident of course and just sprinkle a little bit just to show can you see that is just charcoal some more some more Jenna generous supply there Oscar we don't want to be mean without they shows many spark it's much more likely so this is just charcoal burning in air you see so women
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now say saying is it when wood is pyrolyzed broken down into simpler substances those long molecules of cellulose hemicellulose and lignin are broken down into longer more it's shorter molecules they fought a wide variety of substances now deer Oscar could we try and ignite these jars one at a time because we'll do the gas no actually I tell you what let's first of all do one thing here before we do the gasses and then just look at this pyro ligneous wood distillate which we have
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here and I wanted to show you that the pyro ligneous will distillate consists of two layers I very much hope you can all see them there's a sort of orange layer and at the bottom there is this thick oily liquid which is sitting at the bottom there now the oily layer comes the oily layer is from the lignin part which is the aromatic hydrocarbons which don't mix with the aqueous layer which contains obviously water but three very important organic chemicals and one
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of them is methanol see these two flames burning here they're children these flames here these are little spirit burners but they have methyl alcohol methanol ch3oh which was for many years called wood alcohol and you know why because it was obtained from the pyrolysis of wood so that's one of the things here and the another product which I will demonstrate in a minute is ethanoic acid acetic acid the acid found in vinegar amazingly enough and another
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one is acetone propanone which I have here and I will show that I want you to start off though by showing you first of all that this fluid this liquid here is acidic that it turns certain natural products to certain colors and with their team in mind I'm going to use an indicator which I have prepared here now they're children this is um this here ah it is extracts of red cabbage solution and this you see there's reason why I
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smelt it because it smells rather nice like cabbage soup you know when I was cooking this yesterday I thought to myself what a shame it would be so nice to eat this cabbage soup but I thought no we shall show it to the children because they can demonstrate something very useful so I'm going to pour some of my my cabbage extract soup into there and what I wanted to show there it is it's gone in and I'm now going to add a tiny bit of my pyro ligneous fluid to it here there children and please notice any color change and
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you see it's gone bright red now no bright but it's gonna sort of red now the reason why it's done that is because inside here is in fact is acetic acid the acid which is found in vinegar ethanoic acid but I also wanted to draw your attention to a most interesting fact this cabbage indicator here was not is not my invention it's not teachers it is it is something that has been around for thousands of years and one of the greatest scientists of all time who
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worked in here in this laboratory here and who made the world's most fundamental inventions and gave talks here was Michael Faraday and I wanted to tell you I am very very very lucky that I have got Michael's Faraday's book called chemical manipulation now this is a book especially written for students of chemistry and this was published in 1842 and it's in beautiful condition in here you see in this book here Faraday described how to make a red cabbage
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indicate and that's what I wanted to tell you about it and I actually have the red I wanted you to see a little fragment I'm sure will be able to see this fragment very shortly but while we're waiting for that fragment to arrive I'm going to move on to the next sticks oh let's see these gas jars burn that's right so we've I've told you about free liquids which are found in here we've examined one property of this this is a mixture a mixture containing as you saw an oily layer and etc and I'm going to now show you ask Oscar to ignite the
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jars one at a time and allow me to tell you why because as the process of pyrolysis continues so start which one was first Oscar that one okay now we're not sure whether we'll be able to pull this off exactly but what I wanted to tell you was that the first gas which is produced because they come off in various sequences is carbon monoxide which burns with a blue flame we may be able to get that result depending on it may not burn at all now you see there that's fine Oscar not a problem that shows you that
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when you heat substances and carry on with annex one oscar whether or not Hank that's not did you see that very good Oscar now the next one please this should Bernie they're more beautiful there and you see now the flame is burning differently now that's all those pure carbon monoxide however as the pyrolysis proceeds we start to give off a different type of gas and the hydrocarbon which may burn with a slightly yellow and smoky flame please watch carefully you can see little bit of smoke now the last one should burn with a smokiest flame of all and that
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will be almost pure methane and there it is take that's it can you see that now that graduation there shows you that the composition of the gas mixture changes as the process thank you very much Oscar now what I thank you very much we've got some extra mats coming and very much appreciate for the for the burners are for the acetone thank you very much Oscar that's wonderful thank you so much indeed now what I wanted to show they're children you know I like to do things in slightly larger numbers and I wanted to show you
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a little bit about I'd like to make more carbon monoxide basically and the reason is for me just what she knows fleeting blue flames isn't quite enough so I wanted to show you a far far bigger blue frame with carbon monoxide which I'm going to produce here just allow me to put that on there Oscar could I kindly ask you to remove the gas jars and just take them off thank you so much indeed we are going to be continuously moving things around in order that you can thank you so much indeed in order that you can all see slightly better yeah if
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you take that and take these away at your leisure dear sir take them away at your leisure thank you so much indeed and what I wanted to show you next is how we can make whoops-a-daisy I just dropped a gas jar lid it has not broken so we're still very fortunate multitasking is the essence of today's lecture as you can see now what I'm just trying to find a nice position to put this in and I'd you know what I think I'll do it over here I'll tell you why because I want to exploit the splendid facilities that we have here and show you this experiment over here
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now I am going to make pure carbon monoxide for you now carbon monoxide is a colorless odorless gas the chemical formula is co and it is intensely poisonous it is the fact that it's poisonous is not the issue because many poisonous gases you can smell around and run away from them but not so with carbon monoxide carbon monoxide kills by stealth you can't see it and you can't smell it and before you know it you've lost everything so I'm going to make
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some carbon monoxide now by pouring concentrated sulfuric acid onto sodium formate you will notice a considerable amount of frothing and then I will do my favorite thing which is to set fire to it and I want you to observe the beautiful flame and I can reassure you that this flame is completely harmless and you'll see very shortly some frothing there it is it's beginning to froth as I add concentrated sulfuric acid we replay and there it is now that's deadly carbon
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monoxide coming off and here it is burning with the beautiful flame you see now that's incandescent blue flame as carbon monoxide burns it's of course makes carbon dioxide which is of course completely harmless and as long as the frothing is continuing there but you may like to know so carbon monoxide a deadly poison but in this case it's of course entirely contained in a we're burning it off to make carbon dioxide and Andrus will show you a very clever trick for making us completely harmless in just a
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few seconds in just a few seconds and what I wanted to tell you is that carbon monoxide although it's a way it's a colorless odorless gas and this is an it is commonly given off when things don't turn completely tiny amounts are produced when fuels burn etc but obviously they're controlled to us - let me just add a bit more sulfuric I'm sorry I I just do like this o it and it should froth up a little more you it all depends let's give it a little stir around there there we are a nice
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blue beautiful flame you see etc now carbon monoxide does undergo some very very interesting chemical reactions for instance when I was at school we used to learn to test for carbon monoxide you use pallidus chloride paper pallidus chloride paper was white and when you put it into carbon monoxide it went black it was essentially reduced to the metal palladium which is a hugely interesting metal about which a great deal of research is being done at the moment but another interesting thing about this gas
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carbon monoxide it can actually combine with certain metals so combined with directly with metals to make what are called as carbon aisles and there are two particularly well known iron and nickel carbon aisle will Rio are metals which if you so if you pass carbon monoxide over iron powder or nickel powder at a high temperature you'll get an oily liquid coming off which is intensely toxic but nevertheless it has interest these carbonyls have very
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interesting applications in purification of substances etc and I don't want to go into the detail but the honest truth is they give some very interesting examples of how chemical bonds exist between substances metals normally form ionic compounds with charges on their ions but in the case of the carbonyls the metal is bonded in a completely different way we don't normally see liquids which contain metals as part of them but carbon monoxide is a substance now my
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dear sir if I can ask you to extinguish that what he's going to do essentially is to pour water into it and as he pours water in the flame will get bigger because it displaces the water displaces the carbon monoxide and at the same time it stops the reaction from happening so by doing this we have not only stopped the reaction but we have also reduced there is no danger of any carbon monoxide being and at the same time we had a little bit of extra flame produced which was the most important now the
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next thing I wanted to show you see it is to turn to our liquid product I wanted to start off by telling you that this pyro ligneous distillates which we have a small quantity of here is not something which is useless people have been talking using charcoal for a very very long period of time and I'll tell you about the charcoal in just a few seconds but we're going to focus on these liquids and the people don't actually have to know the chemistry of it these charcoal making charcoal is
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thousands of years old making this pyro igneous this tillage is thousands of years old and you don't have to know how it works in order to use it but I am going to just tell you that one of the uses of the oily layer of this or some of the uses have been for instance in the past and still today as an antiseptic the oily layer has been used to make to make leather waterproof it is used also has been used and this is now these them Egyptians in when they used
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to embalm mummies they used to use this finally Guinea as tar as it's called it has amazing preserving qualities are not only that today I have here a bottle of shampoo I have a bottle of shampoo and believe it or not this is wood tar shampoo and it reeks of this stuff here and it's still used and it's still made today so this ancient technologies still have some uses today in in the modern world but back to fires and you know of
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course it's not surprising that the most of the experiments I'm going to show you they involve fires why well because when wood burns bonfires is the topic well obviously everything associated that comes off from the world will burn as well and this is there for now I'm moving on to the methanol is burning here that's one of the three main products then we have the acetic acid which is here which turns this the cabbage indicator red and now I'm going
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to show you acetone today it's called propanol it's a universally used solvent it used to be used as nail varnish remover has a smell which I like but you mustn't smell these things children I'm a now I am looking for a 50 centimeter cube measuring Celinda there ah thank you very much Andres is my friend always on now I wanted to show you how propylene burns but you know just to burn a few drops would be a completely pointless exercise I'm going to I have made a little steel trough for you here and now when it's the ether is the ether good good good
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Oscar you're going to get ready with some splints to show us the flashover effect which I hope we'll be able to show I'm not sure it made you know what for this experiment it may be useful to dim the lights once the flame is a light though once the frame is alight Oscar there we are and then I will pour the ether in and Oscar will then show you but let's first of all Joshua this is 50 centimeters cube of acetone otherwise known as propanone and I'm pouring it into my steel trough now I very much hope it's horizontal take your time Oscar nog we're not in a
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hurry at all no hurry at all I'm just checking to see that we have yes it is level now please watch carefully a flame will spread there yes take the lights down thank you this is brilliant yes now how do you see the propanone is burning but children this is nothing we're just beginning there's quite a bit of it there now this is the interesting thing also could you stand back to let some people see thank you very much now as this propanone is burning you see and it's in a metal trough that metal will get very very hot indeed obviously
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from the flame notice the yellow color of the flame this is what we call incomplete combustion tiny bits of sorts of produce but as the as the as the trough gets hotter and hotter so the propanone starts to boil it gets very hot indeed and therefore the flame gets bigger and bigger and that's the only reason why I do this experiment cuz I love flames so as you see the flame gets bigger and bigger and then it would eventually obviously go out now while while that is getting bigger and bigger
43:12
allow me just to click on to where's my ah thank you very much it's been repaired now I'm sure you've all seen it so this is Michael Faraday's description of how to make red cabbage indicator and of what I wanted to tell you the greatest chemists in the world use this it says it is very simple and I've got some more experiments with the indicator to show you now the next slide uh you did you did see Michael Faraday by the way I wanted to tell you he photography was invented in 1822 by Nisei for hips he was a
43:45
Frenchman but and it took the whole of Europe the whole world by storm photography and Faraday loved photographed it was it was state of the art side and he loved being photographed and that's a portrait of him which I particularly liked and that that's why I wanted to show it you so now that we move on video children this is a little bit of theory for you this is a little bit of theory for you and visit domain fractious this is taken from a modern textbook on the chemistry of world and it shows you the main fractions obtained from wood pyrolysis
44:16
now pyrolysis is this new work which I wanted you to learn but we'll come back this is almost burnt itself out we'll come back to that in a second and you can practice and learn that all off by heart children it's not too much and I'll explain to you once you've learnt you what it is that you've actually learnt there's some fairly tricky words and there and pronunciation wise now what I wanted to show you next is a very interesting effect I'm not sure whether it will work here because there's a little bit of a draft here obvious for obvious reasons we need good ventilation
44:47
here but what I wanted to show it's gonna I'm now going to pour in 10 centimeters cube of ether now ether is a stunningly volatile liquid and that is it simulates what is very similar to the product and that will vaporize little Roskilde you got your flame ready hang around let me pour it in can you see to turn to a vapor it's old now although and that's what I wanted to show you wasn't that amazing he got there before I did Oscar that was very well done so
45:16
that was a flashover so now the purpose the purpose of showing you this the purpose of showing you this dear children the purpose of showing you this is really a bit of health and safety the honest truth is when you handle flammable liquids and this is present in industry everywhere you have to be phenomenally aware of the way in which they can catch fire and I'm sure you'll agree and in this controlled experiment it's perfectly OK it's like
45:49
the out-of-control but nevertheless it was it was a it was they it was perfectly okay but it's very easy to have industrial accidents etc and the substance that we use on an everyday basis which which will conform with this type of behavior of course is petrol which we use in motor cars everyday unbelievably dangerous and when you handle the golden rule is whenever you handle flammable liquids make sure that all flammables are out of the way you notice here I'd removed all the bottles there is no flammable anywhere and all
46:21
the flammables are illuminated and I also used a small amount so I knew I was covered and in this particular experiment now let's just return back to what you've learnt in the meantime so we have wood and the important thing is wood makes gases and there they are they don't worry about the formally too much I think water is h2o carbon dioxide is the one that we collected in here you see then that doesn't burn that's why we can isolated it methane is the Hydra car and carbon monoxide is the blue one and
46:51
hydrogen which I'm going to show you at the end now that's that now that distillates and the tars they've passed put up a bunch of compounds there and I wanted to tell you that the top three are the ones I've demonstrated for you today ch3 Co H is ethanoic acid ch3 OHS methyl alcohol otherwise known as wood alcohol and the third one is acetone ch3 2 Co all the others are present in the in the oily substance now the last thing I wanted to come on is to charcoal and if can we
47:24
have the next slide please can we have all sorry thank you very much silly and just in case you found that rather easy to learn here is a complete list so just in case children you think you're getting on top of the subject learn this off by heart for Monday mornings test on the products of the pyrolysis of wood and there I I tell you what I didn't I haven't memorized them I just counted them there are 60 of them quite a large list now I have actually I have actually because this is a stunning list I'm sure you all agree that is all produced and
47:56
when you burn wood you're burning all of that lot at once and what I wanted to say is that I put circles around so the orange those are what we call carboxylic acids the ones in yellow are alcohols the ones in light blue are are the aldehydes dark lower the ketones and the dark blue and the light blue are the carbonyl compounds the mixed ones are phenols and the purple ones are our phenols basically derivatives from from benzene
48:26
and there are their aromatics and then we have nitrogen containing compounds based on ammonia and then we have some aromatic ethers and finally some aromatic hydrocarbons so by gum what a complex mixture is it e so when you're burning wood dear children you're burning all of that look I just wanted to tell you another thing about about these aromatic compounds these are romantic combat they called aromatic white normally carbon atoms when they join together they make long
48:58
chains that's a sort of simple compounds that we have that we're primarily made of it cellulose and and Hemi cellulose and all of all the other ones apart from the aromatics however carbon is also able to form a most unusual group of compounds which perplexed scientists for many many years which are based on the chemistry of benzene and they form hexagons like beehives have bees make their hexagonal wax cells they live in
49:28
they this in this particular case the carbon atom forms the carbon atoms form rings of six carbon atoms and the basis for those is benzene now believe it or not another thing Michael Faraday precisely in this building in 1825 discovered benzene and that is another one of the great achievements of this remarkable man of profound humility and there and he made so many discoveries in the
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branches of organic chemistry in organic chemistry not to mention electromagnetism and all the rest of it and to bear in mind that he left school at the age of 13 to train as a bookbinder but more on that on another and you should also know dear children that this year we are celebrating or we are commemorating the 150th anniversary of Michael Faraday's death he died in 1867 he was born in 1891 that makes him
50:33
76 I think and etc the fact is he he was he's buried at Highgate Cemetery which is North London here and and he was so humble that on his grave it simply says Michael Faraday 1791 to 1867 quite remarkable indeed but this year is indeed the hundred and fiftieth anniversary and please remember one of the greatest scientists of all time now are we ready for the next slide yes this is a comment you say when when chemists
51:04
were analyzing only substance is because the 19th century was a time when analytical techniques developed and separation techniques the separation technique of fractional distillation developed and the analytical techniques of chemical analysis gravimetric analysis developed ideas axioms atomic weights friedrich vola who was one of the great chemists working with uselessly big in the early post sort of 1st 3rd and 19th century when he discovered all these chemicals and
51:35
started analyzing and making these lists he said he said to me that organic chemistry appears to me like a primeval forest of the tropics full of the most mark there are most remarkable things and those most remarkable things dear children are all these compounds that huge lists over there now let's see what the next slide says ah and there it is there children I have especially for you prepared this little thing on the left we have the chemical the chemicals the types of chemical that you find in wood
52:07
and cellulose as I've said made up of long chains of sugars and hemi cellulose are sure to change with a variety of sugars and lignin is the one which is gives rise to the oily the aromatic compounds now how do those chemicals arise where does this happen in the wood what is would from a biological point of view well would is basically dead xylem the bulk of the wood itself is dead inside this wood is dead in the
52:38
thing the only part of the wood when a tree is growing the only part of a tree that's alive is the outside part of the tree which is the bark and the layers under it and below the bark you have the phloem which is part of the wood which carries liquids which are made of which are basically water containing sugars and things which come from the leaves you see the water dear children a tree when it grows and exchanges or takes in
53:09
and throws out chemicals through the top and through the bottom through the bottom it has the roots which take up water and nutrients from the soil and those flow up the tree through what is called the exilim whereas the leaves where they are green etc and they by the process of photosynthesis they convert water and carbon dioxide which are in the atmosphere very simple substances indeed and by complex processes they
53:39
convert them into sugars and then into larger molecules such as starches cellulose --is and so for but cellulose specifically is the main thing in would you say what is that thing and the the bit the there is a thin layer in between the phloem and the xylem and that's called the cambium the cambium is the part where these types of to temperate types of transporters or liquid are actually generated and where they grow and this is all just under the bar
54:10
inside the bulk of the tree is dead by the way the word xylem is actually derived from a Greek word meaning obviously wood and that the word phloem is derived from the Greek word meaning bark so do we have these words for various languages now that you see I just wanted to tell you I had a very interesting experience this summer specifically on July the 26th there was a very very heavy rainstorm in our back garden and a plum tree which I had which was beginning to have lots of plums
54:43
unfortunately split in half the stem split in half you see and it is and I was very very disappointed I floated up and I said to myself is it possible to repair it because we're going to lose all our plums that this year etc so what I did was I tied the two halves in the next strip here I tied the two halves together and this is the reason I wanted to show you is because when the true halves they won't grow together by the way they won't grow together but by tying them together you're giving it
55:14
mechanical strength so that the two halves continue to absorb from fro through the phloem and xylem all the nutrients which they produce within all and they can grow independently even though they're joined together and would you have losing out in between this is the important bit it's that SAP which is coming out now it's from that SAP on the maple tree that we can make maple syrup now that SAP is what's from it comes from the phloem and it contains the sugars which
55:45
have been formed ultimately from the leaves at the top and the that SAP and I have the next slide to show you and please watch carefully on that south prob drop we had an amazing plum crop thanks to the fact that I got the tree but on the right hand side can you see that little snail it's having its lunch it's eating the sap from the plum tree you see and that's a very very remarkable thing because you see that sugary SAP is food for others not only human beings but I was very very lucky
56:16
to be able to capture that image now the next word please is pyrolysis and this I'm going to leave up because this is if there's one if you're not very clever children don't worry if you're not and if you haven't learned all those lists off by heart one word pyrolysis pyrolysis these derive from two ancient Greek words meaning fire and breaking down so that's one word please remember and now I'm going to come on to the final product of the combustion of wood which is of course charcoal which is
56:49
left at the end and oscar has already shown you how charcoal burns and is an almost pure form of the element carbon it is the short which is produced when salty flames burn and furthermore it is if this carbon is the source of an a remarkable number of uses throughout their history of the human race and I just wanted to show thank you very much and also we can get rid of the aeroplanes dear sir that would be much appreciated and I just wanted to show
57:20
you a few things about charcoal now charcoal is an impure we finish with that thank you very much for turning up gentlemen charcoal is an impure form of the element carbon charcoals they vary the proportion of carbon in charcoal can be anything from 90 to 99 percent but no matter how long you roast that wood for pyrolyze it for you will never make 100% pure charcoal the thing about charcoal it has a very
57:51
very porous structure and that gives it a large number of uses but before I talk about charcoal in different forms of carbon I wanted to say that there are two crisps there are two allotropes or forms of charcoal the element carbon the element carbon which are not called charcoal but which are here and one of them is here and that is a piece of graphite that's a crystalline form here and I have here a two other one other form and you see here these are pure
58:22
diamonds it was a source of great of great challenge for scientists to understand and I'm going to see if you can make and integers I hope you can see these are real diamonds made out of pure carbon they are very very valuable they're rather small I'm afraid but I very much hope you can see them glittering because it's that property of carbon of diamonds which makes them so very very special they have a remarkable refractive index that makes them useful as precious stones now do you know what
58:52
for many many years scientists could not believe that this and this are made of exactly the same atoms carbon atoms which are found in charcoal now would you believe would you believe that it experiments were conducted by scientists initially in Florence in Italy but even Michael Faraday when he went on a tour of Europe with Humphrey Davy between 1830 and 1850 in Florence and because they were still down T they said how can this be the same as this the most
59:24
precious stone in the universe and they did it by burning by burning and if you burn some graphite and if you burn diamond a very expensive experiment indeed then equal masses of graphite and diamond burn to give the same mass of carbon dioxide is the only product now Faraday actually destroyed that burning process because they showed it to him in Florence and he described the brilliant crimson flame that diamond made now
59:55
charcoal of course is also useful for drawing as a drawing thing so I'm just going to use a piece of charcoal just to draw my experiment number one and it and it has been this is not art this is science and I'm just going to show how we can represent the flask which I did the distillation in the retort flask like this you see and using a piece of charcoal the teacher you see can then illustrate this to the students and we have a ground glass stopper like this
01:00:26
and then we can put the stopper in like that and then we have our drops of distillate coming off here you see and the week this is our pyro ligneous distillate my word it's been a lesson in many new words today and I hope very much hope there it is and here we have for instance the flame which is roasting it here we have the bits of wood and the charcoal like that here and then we put a nice label on it like this retort
01:00:56
flask here and we have a nice arrow pointing to it a Wella and then we can even color it in you see I do love colors and then we can just shade in with a little bit of blue to show the blue cone of unburned gas here then a little bit of purple there you see and then we can shade in the earth the smoke which was coming off which was a head of sort of a dark thank you very much dear undress and then we have a colored the dark color here that was the color of the thing and so forth and you see I am
01:01:28
very quickly making for you a very simple sketch of an experiment which I have done but using one of the products of one of the experiments and that is something you see there while we can have our pyro igneous liquid there with the oily droplets of the of the the Atari residue that thank you very much I'm not going to sign it that would be very silly but please take it away dear sir sir so there we are another use of charcoal now of course do you know what charcoal is also available in shops is
01:02:00
activated charcoal you can buy the chemist buys it an activated charcoal this is used for a tooth whitening powder you see and you brush your teeth with it and it apparently makes them white but I thought they were white in any case but it doesn't matter people buy all sorts of things with the hope of improving themselves and I just wanted to show you that we have here some activator at charcoal is used in water purification has a huge internal surface area and it has the remarkable property of being able to adhere to molecules and
01:02:30
inform loose ponds now as I pour my this is activated charcoal which is heat has been each of a very high temperature to Al's gases I'm pouring my cabbage solution and hopefully it will come through with no color at all so this is now using activated charcoal to decolorize cabbage leaf now it may take a little while to come through it may take a little while to come through because it has to absorb itself onto the thing and my dear and this I'm going to ask you to bring on the Gunpowder box now you see
01:03:02
I'm wanted to show you my personal favorite application of char char core which is of course to make gunpowder and I hope you're not too surprised by that gunpowder of course was invented was discovered or we know the Chinese were the first people to use gunpowder and I'm going to show you today a little bit a very quick experiment now under s if you put that that's brilliant on the floor I am going to very quickly instruct you now you see it's coming through absolutely colorless this is a
01:03:33
wonderful demonstration this is a wonderful demonstration a gain of charcoal in action it has taken out and the reason is that all the dyes in the cabbage in a natural cabbage and also the smells have been absorbed by the way the chemical world weaves is adsorption that means that the molecules in here the tiny particles of cabbage and a smell they are they have been completely absorbed onto the carbon by forming loose molecular links you see
01:04:04
inter molecular forces are strong and they have remained on the charcoal which is a remarkable indeed now here Andres I'm going to start off now that we start off by showing the free please now please excuse me for turning my back we have had a not very much time but here we are the gunpowder was discovered by Chinese over a thousand years ago thousand some people debate how did they discover it that is a remarkable remarkable story in itself which I don't want to go into these but the honest
01:04:35
truth is by intuition at the end of the day we humans are terribly intelligent doesn't matter when we live or what we did but we can work out lots of things for ourselves and intuition is one of the way in which science has proceeded over the ages I am slowly moving this stuff out simply because I want my dear under this would it be possible at you to take this away I've decided to change my policy on this thank you so much indeed and simply because there we can have more space Oscar could you kindly
01:05:07
take this this bowl away that will be most kind indeed thank you very much we're creating more space and I still have plenty to show actually we're not that ready but enough now the three ingredients of gunpowder are charcoal which is in here which are potassium nitrate or lighter here and sulfur which is there and what I wanted to tell you is that and what I wanted to tell you is that you can use charcoal the how did the Chinese discover it what is it sulfur that I wanted to tell you is a
01:05:37
naturally occurring mineral occurs in many parts of the world and especially volcanic regions but deep underground as well huge amounts of sulfur extracted by mining by some we call it the fresh process but there are other techniques as well we get out of the gun it comes out as the pure element sulfur quite remarkable you cannot break self into simpler substances it is simply an element charcoal mainly mainly carbon as I told you and produced when bonfires burn as we've just seen
01:06:10
earlier today but potassium nitrates the clever one and what happens is its form naturally in certain soils the Chinese would undoubtedly have observed this the fact that they're things all and here we have this is thank you so much I have especially prepared for you dear children this is a collection these are potassium nitrate crystals and I have grown them for you in this speaker they are very beautiful indeed and you are most welcome to come and look at them and the honest truth is in many hot countries such as in India and in
01:06:41
Southeast Asia these crystals grow naturally out of farmyard soils and where they grew and where there were embers of fires burning those fires burns much more brightly and those are now what I'm going to show you is what the Chinese learn they learn some examples of these gunpowder in action now as we going for it I wanted to tell you first of all that the gunpowder mixture which the Chinese invented and we're looking at let's say a thousand years ago contains 75% by mass of
01:07:13
potassium nitrate fifteen percent by mass of carbon charcoal and ten percent by mass of sulphur and that was those ratios which sound like beautifully elegant numbers were established purely by empirical means there was no chemistry you can't write a chemical equation today chemists have not bettered the composition of that the ancient Chinese had learnt and as I repeat this is pure through sheer intelligent and intuition now here I have a mixture of those three which is
01:07:45
just to show you how it burns if you do this as an experiment at home or at schools and it is not particularly dangerous you'll be very disappointed with the outcome because this is how a mixture of these three powders burns on its own and I have to warn you this is not spectacular it will happen don't worry there he goes how are the Gunpowder going bank isn't it's not going to make you it's not going to make you jump out of your seats is it now please observe carefully
01:08:17
please observe carefully can you see these little blotches here that was very slow burning these little blotches that's basically unused potassium nitrate the bits of black onions child they're simply the mixture isn't good enough to end to enable a rapid combustion however what the Chinese then understood they they then using the technology of a flower flower Mills etc they thought wouldn't it be good if we made them powder them into a much much finer powder and then when they made a
01:08:49
much much finer powder they ended up with something like this now this is by the way they called it serpentine powder this is coarse serpentine powder and this here is milled serpentine powder this has been ground this has been milled in a ball mill with red balls crushing it up make it into a very very fine powder indeed for several hours for eight hours now watch how this burns it's quite a bit different it's faster and secondly can you see that there are no residues of yellow now
01:09:24
not only that they venues bread making technology in other words dough mixing with water etc and are and baking it but not in the case of this they took the milk powder they then added to its small amounts of water and alcohol and then they and they put it through a sieve and they allowed it to dry and they ended up with something like this now this is what we called corned powder now this burns quite a bit more dramatically still so
01:09:55
please watch carefully because this will hopefully be quite a bit faster I'm just going to wait it takes a little while sometimes I may have to be daring and shove it ah ha oh just look at that now that wood no no no you know please I know look at that beautiful smoke ring that we've got wonderful one now that you see now that you say can that make something go bang oh yes it could because this is this is definitely gunpowder and that you see the result of human ingenuity that doesn't require a great deal of theory and we not have
01:10:27
improved now when the Chinese made this they said brilliant let's now let's now use this for some purposes thank you very much and I'm going to show you very quickly how to make a simple pyrotechnic device using that Nadia Andrea I just wanted to undress I'm going to very quickly wipe down the bench so please excuse me I'll just quickly wipe it down we must have dry circumstances thank you very much indeed thank you very much indeed this is wonderful and I'm just going to quickly make for you a Chinese
01:10:59
firecracker a chai now we have two sheets of a4 paper for this now I need my tape and the scissors brilliant thank you very much indeed and the way we do this is well we roll up first of all we have to make and you know the Chinese they always interpret it or lots of things they set up in terms of dragons and things and they call this gunpowder the fire dragon horses you know so things along they're very imaginative and that in the course of human culture we people are very we like having a picturesque ideas or analogies thank you
01:11:31
that's men now excuse me if we cut this off if we cut this off here under this okay we cut this off I will now operate up there and I will now wrap this taper up now what we're going to do now we're going to now wrap this up like this and intimated that you I'll tell you forgive me the roll just give me the roll let me wrap it up from the roll because it's easy cut you just cut that off there just cut that off there thank you so much and the way we do it is this it gives you a and what we're doing we're strengthening it you see we're now making a prison for
01:12:02
the fire dragon that's you know sort of way you can look at it in a picturesque manner and we're making it stronger simply by wrapping this around here and there we are like that and now we trim it off with a pair of scissors thank you so much take care not to let the tape go there thank you so much indeed now what are we doing now we now have a tube no one will deny that we have a tube and now what I'm going to do is to seal the tube off again because we are going to put some gunpowder in obviously awesome black power the way we do that we touch
01:12:32
off the end like that and then we Bend the end like this and then we put more tape on so now thank you very much indeed we wrapped more tape around it like this and basically the more tape your wrap the most the stronger it is now there will be the noise when the fire dragon escapes so we have this again thank you very much the androids now what I'm going to do I'm now going to put in some of my powder some of my powder which I have here and for this purpose I have
01:13:02
I've got a small jar which is probably labeled black powder and a small spatula at the end Ernest a small spatula and a small jar they labeled would be probably be labeled black powder fast or something along those lines is that the one yes sorry I have these I have smaller containers at beer children and have you got a small spatula with a small end on you may not have a that's the one a whole handful every tool that mine thank you so much Andy now we put approximately five or six spatula
01:13:33
measures in here I'll do it carefully so you can all see what time day one then two three four five I say and one for lap seven there we are it will have more than air yes yes so there we are so here we go now then down there and now what we now do we use our ramrod here to test to see whether it's all gone and to ram it down so we can now test to see it's now to approximately there what we now do is we cut the end off here we cut the end off
01:14:04
here and then we put a fuse in we put a fuse in with which we are going to set free our fire dragon inside thank you this in here and thank you very much under this we now put it like that so that's now going inside there and then we bend it over we bend it over like this to make a solid to make an absolutely closed okay enclosed cage so if you excuse me I'm bending it over and now going to put lots of tape on it to give it to make it very very strong to
01:14:37
bind it and inside like this so there we are I'm just binding it up now can I have my Bangor cage please my dear boy thank you very much now at this stage at this stage we are now ready to go and I wanted to tell you what this you see I'm going to set this on fire now if I were to put it on my hand you see like that you will all agree that wouldn't be a very bright man okay because the reason is it might make a loud bang it might rip a hole in my hand so what we do is we're going to it's
01:15:08
called a firecracker I like to call it a fire dragon which there to be released we put it in a cage this is this is what I call a Bangor cage or a firecracker cage and it's to protect to protect me obviously from the effects of this and this is steel so there's no way now there is a shelf in there which you can see and there are two ends which have got holes in them and that is to allow the any product to come off now do we have some safety goggles and I'll ask Oscar to do the ignition and thank you very much and eat and rest Oscar safety
01:15:40
thank you very much easy there is there is no real now the firing range are we have another pair of safety goggles down under this we have another pair let's all wear safety god now the firing range is here too there okay because the only way can escape is from there to this Oscar I will ask you to light a fuse and I will then put the end on okay so there's the fuse if you can light a fuse I'll put the arrow and I'll hold this this doesn't always work when you make make a little bit of bang a little bit of a spark
01:16:11
okay so that's please let's have the fuse on now move away I'll step and out of range services shortly hopefully our fire dragon will be released on this stage blast wave through the thing I'm
01:16:49
sorry about that now Oscar some rubbish here that's rubbish right now we have now come to the end of the topic which is concerned with the products of the pyrolysis of wood and so when you're burning wood you burn all these products but I now want to say what happens when you burn the wood burning is one thing pyrolysis is that pyrolysis gives you all these products here but what
01:17:19
actually are the final products when wood is burnt when you burnt the charcoal when you've burnt all your pyro ligneous food when you've burnt your hydrogen your methane and your carbon monoxide the answer is this there are two main products and they escape into the air they are called carbon dioxide and water vapor from all that huge mixture carbon dioxide and water vapor are produced when wood burns and what is most interesting those are the two
01:17:51
ingredients from which wood was made in the first place which is quite remarkable this is the cycle of nature now I wanted to focus on the one product solid product which let's left behind I've told you that carbon dioxide and water vapor are the two main products which go into there but left behind we have a product which I have here which no one ever draws any attention to but here it is it is simply wood ash it is the ash which is produced from the
01:18:23
burning of the wood and believe it or not this too has had a huge role in the history of mankind no we humans we don't waste anything at all in any process dear Andres could I ask you to do me a favor and take away our beautiful flask here which has become full thank you so much just with of tripod with everything thank you watch out it that's it I will just mop down I will just mop down the tiny spillage and then I wanted to show you something about the properties of
01:18:54
wood ash and I'm going to start off by pouring my cabbage juice through the wood ash so I'm going to put two tips um I'm going to if you don't mind move this into the center phase now into the center thank you very much Oscar that's much appreciated now I'm going to now move these three flasks on the beautiful sheets of white paper into center stage the reason is I wanted to show you now what is in here you see the cabbage water has been
01:19:25
totally depolarized by our activated charcoal I'm now going to take this is ash from a wood fire in my back garden and I have I put it through a sieve just the kitchen you know a kitchen strainer a tea strainer big tea strainer or a metal sieve just to get rid of some of the larger bits there is my wood ash going on and let's see what wood ash is actually made of this is a very interesting thing because there are many very useful substances this is what we call the in combustible part of what the
01:19:56
part of the wood that doesn't burn it's the bit that gets left behind at the end now if I now pour through this my cabbage juice please watch what happens I'm going to very very gently pour the cabbage on and you'll notice there's a lick a bit of dust going up etc and very shortly the cabbage will start coming through and as the cabbage starts coming through you will notice hopefully a very very significant change in color it takes a little while to come through what I
01:20:28
wanted to tell you is it's going to come through let's just wait it's almost there because this has played a most important role in the history and I'll tell you what this ash has been used in soap making thousands of years ago even in ancient Egypt people were already in ancient he we're already aware of the most important ingredients that can be used in this in this wood ash to make soap and for that reason the liquid which you can see coming through now
01:20:59
dear children has a different color it is coming through yellow and the reason why it comes through yellow is because in this ash which I have there are two very important compounds containing two different metals and one of them is called potassium carbonate and the potassium carbonate and causes the water to be alkaline by process called alkali hydrolysis please don't worry if you don't understand but seeing is believing and you will all agree that this is not
01:21:32
red and it's not colorless it's coming through yellow and the reason why it's coming through yellow is because the wood ash is reacting with the water to release potassium carbonate into solution which is soluble in water and to make that potassium carbonate into a solution and when potassium carbonate dissolves it undergoes the process of alkaline hydrolysis making an alkaline result which is the yellow color that you see there and this was used as ly ly
01:22:04
E for soap making boiling up a concentrated solution of potassium carbonate with natural oils with plant oils vegetable oils etc used to use beautiful soaps and perfumes soaps were available have been available by humans for thousands upon thousands of years now let's do another experiments now let's do another experiment to see what else is present and what I'm going to do I have some I have got some wood ash I'm putting ash
01:22:36
inside here and I'm going to add to it a few drops of hydrochloric acid now please watch carefully I'm going to put some lime water which is a saturated solution of calcium hydroxide now for your information children this is very commonly used for testing for carbon dioxide it's a standard chemical test but I very much hope I can show you this working because it does show what it does show is that thank you very much now I'm gonna see if you can if you can put the acid in give it a generous
01:23:08
squirt I will show that you little froth mmm nice and easy there's no hurry now can you see it frothing dear children can you see it frothing now it's frothing because it's giving off the gas which we call carbon dioxide please watch carefully as my lime water as it bubbles it starts to turn milky and the reason why it's turning milky because wood ash is in fact primarily a mixture of calcium carbonate and potassium carbonate and why is that well because
01:23:40
wood requires the two minerals metals potassium and calcium for its well-being it enables the gases it enables the wood to function the its sensitivity to light and heat is increased etc now dig those two metals which are present in wood I wanted actually to tell you a little bit about them the reason is they were both discovered yet again in this building but not by Michael Faraday by Michael
01:24:12
Faraday's mentor who was Humphrey Davy Humphrey Davy was an extraordinarily flamboyant character he was he used to give amazing lectures in fact the reason why Albemarle Street became the first one-way street in London because because Humphrey Davy was so amazingly popular people used to fly he was an amazing character this by the way is just to show that topic that we're on I hope you've seen it's not too difficult to understand carbon dioxide as a gas water as a
01:24:46
liquid and ash as a solid there that's a Humphrey Davy he was one of the first directors of the Royal Institution here and he made remarkable discoveries precisely in these rooms he was first who discovered the potassium in 1807 by electrolysis and calcium in 1808 by electrolysis and we are going to demonstrate each of these metals to you reacting with water whoops-a-daisy I'm not sure that's so that's a that's Humphrey Davy there
01:25:16
that's him that's a caricature he was such a character he used to do experiments with gases and gases were that time very fashionable andthat's Humphrey Davy holding a bellows there etc that's this is a very well-known cartoon published in 1801 that's for our next topic now we are now going to therefore to a demonstrate show them now for this demonstration I'm going to ask for the lights to be turned off please the or not off or reduce um Andrus is
01:25:48
now going to add some piece a few pieces of potassium to the few pieces of potassium to the to the water there's water in there a few prett now this reaction only lasts about five seconds so it's a very short reaction indeed and if we could turn off the lights please this will be very useful because you will see a beautiful lilac flame in there for a short while this precise experiment used to be demonstrated by Michael Faraday here in the 1840s with potassium which
01:26:20
was then a newly discovered metal please sir and that's potassium reacting with water there you saw a little bit of a lilac flame it catches fire by gum it's dangerous and it's flatus now if we if we come back to that in a second I will now show you calcium reacting with water and let's do that over here we can do that actually let's do it over there so you that may that I will now show you calcium now can't you reacts with water but it is much less dangerous and what we're going
01:26:51
to do here we're going to pour in some pieces of calcium and I'm going to show you what's going to happen here goes out this is water and this is calcium pour in a few lumps and it starts to fizz very short they will start to fizz and it gives off the gas which is called hydrogen in very very large amounts and there it is and we can sit fire and as you see if we can have the lights down you see a beautiful brick red flame and that brick red flame is being caused by hydrogen which is
01:27:23
generated from calcium as it reacts with the water and you can have no doubt about that was a very large amount of hydrogen coming off now the next thing I wanted to tell you this will continue to fizz is that in each of these cases can you see the product of the reaction here is a clear liquid it's simply water and it's got no it's a it's colorless it has no color whereas here the calcium has made a milky liquid now that milkiness is caused by calcium hydroxide which is
01:27:53
not soluble in water potassium is an alkali metal fully soluble but calcium calcium hydroxide is an alkaline earth element and count'em is an outline of and on each occasion we have a solution which is strongly alkaline so as I pour this in here the cabbage juice should go a yellow color and we swirl it around hopefully it'll go yes it's going it's not fully yellow not enough potassium this one should go much more yellow and we just pull the whole lot in and you
01:28:24
can see there so once again the alkalinity now our mixed experiment is with the that this is your speciality this is the yellow pal day it doesn't matter yellow powder yellow powder yellow powder now this by the way this is a very unusual experiment this is which I call the flying spoon expect now I do have to warn you the banging this is very very substantial and what we have in here is not gun powder is not gun powder which contains a mixture of
01:28:56
potassium nitrate charcoal and sulfur but is in fact potassium carbonate potassium carbonate etc and and and what wiII happen is we have two spoons here what we have is one spoon here and one spoon there now while that is happening we're going to lead us on to the next topic because this makes a very loud bang and this is not gunpowder buts yellow pal the Gunpowder is called black ties here this is going to make a very loud bang and a spoons will go shooting up into the air and that leads us into
01:29:26
the next topic which is bangs I'm continuing because I'm rushing on to finish now we now have Theophrastus bombast the celery ollas bombast as von Hohenheim was the first person who had a theory about allow this bangs that we ever heard which were gun power which were thunder thunder and lightning used to terrify people now this is going to be very very loud bangs indeed and the spoons will go fly so please be careful now the fact is that he put forward the theory that thunder was caused by aerial
01:29:57
gunpowder and we have gunpowder before but in the air that turned out now this please continue because when they melt the bang is very loud indeed it's going to be in ear rendering deafening and it's an unbelievable react when they melt that'll be ready to go I'll carry on talking that his theory of aerial his theory of an aerial gunpowder because he thought it was gunpowder exploding in the skies gave rise to the Polish alchemists theory of an aerial miter he thought it was nighter that had
01:30:28
something about it in the air which made things burn better and breathe better he published his theory in 1604 it was the most widely read Theory alchemical theory for over two hundred for two hundred years nearly fifty six editions in six languages was published and centavo uses work and that's a sort of stuff he wrote just a couple of quotes xavier has created by the earth and we're ready to go are we police cover your ears this will be a very very loud bang I'm continuing to talk as I'm too
01:30:58
terrified to do anything less now father is in the air a secret food of life which in the night we called you and by the day real fire was an ism could you feels better than the whole of it is the water around you out of which nothing's the saltpeter of the philosophers by which all things are grow that's one and there's our flying spoon and the second one about to go now and second one about to go now it's a saltpeter which is making these explosions now they're children although Paracelsus incentive Ogas eventually led
01:31:30
to the discovery of oxygen we now know that thunder and lightning are actually caused by electric by discharge of static electricity I have here a Wimshurst machine which I show so there it is and I'm sure you'll agree now I'm going to quickly twiddle the knobs here took the them now as you see can you watch this is what makes thunder it is an electric spark going off like this an electric spark going off like this and
01:32:01
that electric spark is the spark which causes a huge expansion of the air and which causes of a very loud bang which with here it's a tiny crack in lightning huge 20,000 degrees centigrade 43,000 and thunderstorms daily on this planet a huge huge number I am now going to show you very quickly we'll just cut things off to the end so that's what causes the thumb and during this the during this we have these chemical reactions taking
01:32:32
place which give rise to nitrogen dying around we're going to do just this that's sorry that's the next one there that's that we're going backwards so wrong way sorry silly Sheila I'm pointing ah those are the two chemical reactions that occur when lightning strikes now nitrogen dioxide gas and ozone are produced in the atmosphere now I have an experiment here which doesn't take very long but it's extremely beautiful in this experiment we generate nitrogen dioxide in tiny quantities and it's in
01:33:04
large amount sorry huger I've got copper in here I've got water containing sodium hydroxide and phenolphthalein and ammonia in the last I'm going to pour now watch dear children because when there are thunderstorms this gas is produced you don't see it as a dark-brown gas you see it you never see because it's very dilute but this gas is acidic and this gas will make this purple so this so this is produced during on this nitrogen dioxide this is acidic turns phenolphthalein cow this in turn is reacting with ammonia
01:33:35
which makes that color now while we're doing that will now set up the last experiment so we're coming on to the all I wanted to do hydrogen hydrogen is that the this is the last expect carrier watching is there a remarkable sequence of reactions in copper makes copper nitrate there's nitrogen dioxide here this is acidic and NASCAR ammonia very shortly that will start cooling down and these two waters will get sucked back into there and you'll be see a spectacular range of colors develop in this copper nitrate there which Alex
01:34:06
which I won't bother explaining but it's great fun now what I'm going to do and I invite you because the colors are really very very beautiful dear children hydrogen is present hydrogen the lightest gas in the universe is present in one of them one of the products of when wood burns and so it's appropriate to show you how hydrogen burns and in air where nitrogen burns in air it simply makes an orange it's nothing it is nothing that loud this is not at all a cover you're in sales that's it it's a
01:34:38
beautiful orange flame this is pure hydrogen burning it's not worth talking about that that's it now this here by contrast by contrast their children this year by the way we're watching is children watch carefully we're now sucking back we're cooling down this is now sucking ammonia through tea which is outlined phenolphthalein goes pink again this now gets up watch carefully this nitrogen dioxide dissolves with great
01:35:08
rapidity in the water and so this is sucked from there to there this one gets sucked from there to there and watch the beautiful sequence of colors which you'll see that now well that sequence this going there I'm now going to set fire to the balloon I'm now going to set fire now chosen this is what pilâtre de rozier the French scientists used to call re opponent their thunder air this makes were very loud by it's a mixture so close your ear we go
01:35:38
so that's image now final experiment now is the trough we now have the final experiment here children watch these colors develop during this final experiment during this final experiment we shall be creating real thunder and lightning in here and I'm going to ask you couldn't we have the truck Oscar leave that watch these colors they're very beautiful we'll have a butcher's at them afterwards I'm now going to create for you real thunder and lightning here
01:36:10
and at the end of this thunder and lightning experiment children I'm going to ask you to be completely silent and I'll tell you why this is not that terrifying by the way actually it is but who do we pretend here you're all scientists here by now I've won you over so you're not afraid of anything now what we're going to do can we take the distillation away there Oscar and get me the if you can now get me the the the the the guncotton here we are I'm going to I have two balloons here I'm going to wear this by
01:36:42
the way this is my special safety mask I told you why this is in case we have a flasher not a flash over but a flash powder now what we're going to do here can you see how beautiful these colors are you're going to have three layers there now that needs to be much lower the blue needs to be sitting right on there we'll do that in a second we'll just do that in a second now what we're going to do here children and this is the very last experiment of the day you just keep taking away Oscar could you please keep tidying things away very last and I'm going to put this slide the last slide is here now this is today
01:37:14
summary this is what you've learnt today is that when wood burns there are two separate processes pyrolysis and combustion combustion is oxidation pyrolysis as thermal degradation please remember that the only thing you have to remember now we're going to have to put these balloons down in a minute and we need to China I tell you what under this if you can that's it just make them lower that's fine that'll do these are balloons filled with a mixture of hydrogen they're going to be the thunder I'm lying here a rapidly burning
01:37:45
fuse which is known what's up at the diversity ah too bad we'll just have one it does happened to the new you see even in the hurry even the best scientists don't worry children will have one it'll be perfectly good the one is better than none now listen carefully now listen carefully listen carefully children one is fine that will make a little bang that will make a pretty loud bang it's not that loud but it's not the
01:38:16
end of the world now what I'm going to do here what I'm going to do here can we take away the the guncotton now can we take away the box with the gun cotton I'm going to quickly make up too few spell to flash powders here and what's going to happen I'm going to set off my we're back to our campfire that we had at the beginning the campfire at that begins you remember I poured some liquid onto a powder I'm going to do the same here today that liquid which should be the powder which uses potassium permanganate and that's what my secret
01:38:47
with my Scout success was and the liquid we use is going to be glycerine and that's what you put on that starts burning and once this has gone off there will be a loud bang and two flashes I would ask you all to be completely silent and I'll tell you why because we're now going to return to the sociology of our campfire we're going to return and we are going to hear the traditional melody the traditional melody that is played at the end of all
01:39:19
campfires where many people gather together and you I'll ask you to listen carefully and after that I will be very very happy to take any questions so this is the final experiment after this please remain completely silent it's not going to be that dramatic because one of our balloons has now floated up to the ceiling I'm making up here by the way and I'm having to have them to take great care here I'm making a flash powder which basically enables the makes
01:39:51
it look as if there is a real light thing it's like a real lightning it's a high intensity it's magnesia mixed with potassium chlorate it's a high intensity ultraviolet light of the same type that's given out by real lightning the obviously the amounts this will make a flash go up into the sky there will be one flash here and there will be another flash so this is going to be Thunder this is a lightning flash and this Hill here will be another lightning flash oh let's hope it works you know this is all
01:40:22
a bit of a thing I think we'll just sprinkle this liberally everywhere damn it I can't waste chemical now then this goes into the bin there now so dear children please what listen carefully the flashes are really very bright indeed so you shouldn't be looking at them directly the bang you've already heard once so this is not going to be any louder but it will be about so that we are both um please look at this beautifully please look at this beautifully I'm sorry Android can I just interrupt a second the bang will be a
01:40:54
lot louder this is a hydrogen option blue so it is essential that you have your ears covered with your hands not your fingers where Andrew does it okay thank you very much children I hope you're all ready thank you very much now listen carefully I'm going to pour on I'm going to actually take me goggles off because this isn't dangerous actually the earlier one was dangerous this isn't I'm going to pour this on and it will take approximately a minute now the important thing is please remember complete silence once this has finished that's the important it will burn there
01:41:26
will be a couple of flashes hopefully a bang and I've got my fingers as well because I want you all to feel that we're safe there like this like me like this so here we are hopefully it'll and then complete silence when you'll hear the final tune of the day the fire is burning and going and we're waiting for the final tune of the day
01:41:56
[Music] thank you very much for your attention I wish you all a very very good evening thank you very very much indeed can I call Andres Andres to the floor thank you very much under this light lifting off static musicians musicians we'll have the
01:42:40
musicians please thank you very very much indeed thank you very very much indeed musicians people thank you in a very very good evening to all thank you so much

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