The explosive history of hydrogen – with Andrew Szydlo

foreign [Music] is the lightest gas in the universe its Discovery by Henry Cavendish in 1766 caused an unbelievable sensation people had never ever seen that you could float something like this you could take a a they used animal bladders in those days but you could take a balloon I've now got rubber balloons which we have now got today and you can fill them with this wonderful gas and up and up they go and The Sensation was so great that when Henry Cavendish who was the first person who defined this gas hydrogen had been known since the Middle Ages but people simply called it an uh an inflammable smelly air that's how they used to describe it but today you see it is certainly very flammable and it certainly Burns as you will see but above all its use as a lifting agent uh has been has been history a sensation which I'll talk a little bit about here and you have you see I have a balloon here which is suspended in air it's almost exactly in a condition what we as we call static equilibrium it's going up a little bit and I can have a tiny little bit of blue tag and the point is you have to keep adjusting the weight because the um there is the hydrogen continuously escapes from the uh from the balloon now there you see it's almost perfectly static now we have a beautiful Airship you see here and this was the one of the great uh uses of hydrogen when it was first discovered could we just do a little round please with the Airship and gently take her back to the hanger you see um it's a radio controlled of course we have wonderful facilities for doing this sort of stuff at long range you see and there it is beautifully floating in air the uh the so wonderful was the invention of hydro the disc recovery of hydrogen and its application for filling balloons that people used to do anything they could to fly and flying high above the sky was one of the greatest Ambitions and challenges but what I wanted to tell you about and when people flew by the way in air balloons not that no need of those did they do this for pleasure but they also did it to take measurements of the atmosphere at various Heights the pressure of the atmosphere the how much water vapor there is they measured the composition of the atmosphere to see whether the air high up was the same made up of the same gases as the air low down and so forth and they use it for traveling there was a whole wide range of applications for over a hundred years about 130 as I will shortly explain can we just have the next slide please because on the next slide you will see um this is the final stage which we reached was the the great airship by which means of which you could travel across the Atlantic they were filled with hydrogen there was it was a luxury way of traveling about 80 people could travel it took about two or three days because the journey was long but it was a magnificent way of experiencing um traveling in a silent way floating through the clouds unfortunately all of that as I'm sure you know disastrously came to an end in 1937 I believe okay we see the next the next photograph which should show you um the which we'll show you could I have the next side there you are and this is of course the famous uh disaster when the Airship uh it was caught the Zeppelin it's a caught fire no one to this day knows exactly why it caught fire there are all sorts of all sorts of um theories about this but the honest truth is that one event uh brought about the end of Airship traveling and that's as I say this was in nineteen 30 I believe in 1937 the Hindenburg disaster as it was known but let's go back a little bit in time can we just have the next slide please and there is the man who discovered hydrogen now you may say well how did someone discover hydrogen was he sort of pottering around his name was Henry Cavendish he was a brilliant scientist a physicist a chemist he was interested in everything about nature around him and a brilliant experimenter he was extremely shy he never posed for any photograph any pictures to be made of him and he this portrait of him is the only portrait that exists and it was taken because the artist hid behind the curtain when and and as as Harry cavidish walked by at a meeting the artist quickly sketched the outline and so there we have the man but you may say well how did he discover hydrant was he just sort of messing around with chemicals was he just pouring acids around no you see at the end of the 18th century the big topic then that was being studied or investigate there were several topics but one of them was the idea of the concept of a gas we today we know there were gases we've heard that word since our early days but gases were identified as individual substances substances with their own chemical and physical characteristics and the and the fact that air is a mixture that is probably one of the greatest discoveries of Science of all time because for thousands of years people didn't recognize the fact that air is today we know a mixture of nitrogen oxygen and so forth and when gases were identified and they were they were simply called different kinds of air so hydrogen was described as inflammable air which burns and that's how Henry Cavendish described it can we have the next slide please the next slide you see um the next slide should show ah that is a balloon being filled with hydrogen well I am going to show you a chemical reaction here in which we can meet hydrogen in the laboratory now I'm going to make the hydrogen in the laboratory by adding dilute sulfuric acid this is an acid which which you um which you meet in schools formula h2so4 and I'm pouring it onto a metal you see the way that hydrogen was produced historically was by reacting various Metals with acids acids have been known since I've met since the dawn of humanities I will explain later and metals have also been known for many many thousands of years and what I've taken here is sulfuric acid which has been known since the Middle Ages and the zinc which was actually discovered in about 1740 but they used to use iron filings in those days but I'm using zinc today and the reason is it's more reactive and it reacts more rapidly so what we have here is a what we call a flat bottom floss this is a thistle funnel and I poured my acid in zinc is in there there with a little bit of copper sulfate acting as a catalyst and we now have a gas jar and you see this beautiful gas jar here which is filling this type of apparatus was by the way was used extensively by the brilliant English chemist Joseph Priestley it's called pneumatic chemistry you they use the the displacement of water biogas and he was able to collect the gases there now I am going to shortly show you that hydrogen is a flammable gas and during the course of the lecture today I shall be showing you how hydrogen is also explosive so I'm going to place my candle here you see that the flask is filling with the rather the gas jar is filling with a colorless gas because that's the way it is described and there are many many colorless gases of which nitrogen and oxygen found in air are examples but you see when this now will fill with hydrogen I will now take off this by the way this is called a beehive shelf that orange thing there and it has a hole in it and I'm now going to take the jar off you see place a lid on it like that and then I shall take it off and put another jar on now I'm going to show you something very special I'm going to sit this on fire and this is almost pure hydrogen I want you to listen carefully because it does not make a loud bag it burns with what we call a thub please listen nothing special nothing special you see but I am now going to show you something quite different you see this jar here it's only half full it's only half full I am now going to let the water out look now it's gone and what's called instead of the water is air we now have a mixture of air and hydrogen please observe how this Burns it is rather quite different and you see that was a squeaky pop now that you see is a much more rapid combustion that's a much more rapid combustion and indeed it does a completely different effect now this reaction will continue I have Andres here I backed several helpers you'll be meeting them this evening I'm going to ask Andres to kindly remove this apparatus now please that's a that's a gentle Pace Andres while I continue explaining a few important bits and pieces about how hydrogen is made so for those of you who are in school year nine and above the typical reaction is acid plus metal makes salt plus hydrogen as I said this reaction has been known but not interpreted that way for many many hundreds of years and um Robert Boyle for instance also made hydrogen in 1650 or something like that which was over a hundred years earlier but he didn't understand it in those terms he simply called it flammable air or inflammable air and it was very very smelly because the iron he used was very very very very impure and so the hydrogen had a foul smell now I am going to just show you that there's another way that we can make um hydrogen but I'm going to do this later because I just remembered that we ought to move on to a very very important idea Andres could we now fire up this equipment here while Andres is firing up this equipment which is quite a complicated experiment we need to I'm going to now there's no water in here so Andres will bring some freshly boiled water into our boiler and um and we're going to explain a few things to you the fact is that when hydrogen was discovered was a time in the history of science when people were contemplating ultimately what are things made of how is what is matter made of um how do substances react what actually defines a single substance so hydrogen was defined by the fact that Henry Cavendish measured its density he measured its combustibility and he also measured the ratios in which it would explode the most violently when mixed with air so that was what um Henry Cavendish did but furthermore Henry Cavendish also noticed and not only he that when hydrogen Burns it seems to steam up it seems to make Steam and that became a very very big topic for the scientists of the day is what happens when hydrogen burst and they thought this is impossible how was it possible they didn't call it hydrogen those days they simply call it flammable air and they thought it's how extraordinary how is it possible that something can burn and make water it is with very Noble ideas in the history of science the ideas of how things burn what happens when things burn people it was very very difficult to understand because you see when you see a gas burning or wood burning or coal the flame goes into the air and you don't consider that it's made something different we now know that we now know that you see and the things disappeared into the air and people thought that's the way burning happens and I have to tell you that when it was noticed and Cavendish and other scientists were very very keen observers they noticed that when the hydrogen gas burnt which was incidentally great fun everyone used to love burning it and making pops and bangs with it because that's what I'll be demonstrating but they still they noticed though not all of them when it burns it makes a bit of steam especially if you do it in a vessel where you can collect the vapors and there for the first time was born the idea that perhaps hydrogen is present in water I'm going to show you an experiment here in which is a remarkable demonstration in which we actually prove that hydrogen contained is found in water as you saw Andres just poured in some freshly boiled water here the water is here it's in this canister here and we have a burner here which will shortly make this water boil it will take a few minutes as I said that I bought to explain things as I go along once this water is boiling we are then going to pass it over iron which is in here Red Hot Iron it'll be heated up with burners to a very very high temperature and after that it's reacted with the iron it'll end up a gas will come out of here and that Gus I hope to demonstrate to you is the gas which we call hydrogen now while we're waiting for that to boil up I just wanted to explain to you about this Splendid illustration of a balloon being filled with hydrogen you see filling a balloon with hydrogen we can do this very easily today you know you simply say you you go you um you go you get your hydrogen cylinder or you can make some in the chemical reaction but if you want to fill a balloon with hydrogen to make it Fly that's an enormous undertaking and the required whole teams of people and what I wanted to say is that the balloon which you said see they're being filled with hydrogen that by the way that picture is 10 cool science textbook which was published in 1857 as you see the the the the these enormous scale of it it had a diameter of about eight meters and they required half a ton of iron filings reacting with a quarter of a ton of sulfuric acid and the sulfuric acid was contained in those barrels which were lined with lead it was a very very smelly operation but people it did and the balloon was made out of rubberized silk and it was tied down with ropes and it took three days to fill the balloon so this was an amazing challenge this wasn't easy just to go out and say oh let's fill a balloon with hydrogen and that's the way that works and these balloons became very popular there's a man called Charles green his name was Charles green throughout his lifetime from about 1780 to 1860 he made 1 200 balloon flights that gives you an idea of the excitement which flying by balloons gave to people now we're back to the subject now of what happens when hydrogen Burns is it possible that hydrogen makes water and as I repeat when people used to use hydrogen then in those days they didn't call it hydrogen they called it flammable air and that was the only way they they described it and I'm going to show you now that this boiler can you see this stupid this is what we call a pressure tube I'm now going to point it's a it's a pressure relief valve should I say if I squeeze this tube now and three it's very shortly steam will come out can you see the steam that means the water's boiling if I squeeze it so that the water steam can't come out you should see the tube the level can you see that you see that's my safety valve and this is what all wherever you have steam boilers you must have a safety valve now their underest we need to get this to Red Heat please so Andres is now going to heat this now we're going to know we start passing it once it's red hot we have just rehearsed this literally once or twice these by the way these experiments used to be popularly demonstrated and now they're quite difficult to to to do and what I'm going to say is Andres is now going to use a Blue Torch in fact two blow torches that tube is full of iron Nails it's full of iron nails and we're going to get them to Red Heat once the iron nails are red hot then we will pass the steam over now this experiment was famously done by a brilliant French scientist Antoine Lauren Lavoisier because Lavoisier was doing this experiment to see whether you could actually start with water and make hydrogen now when he did that he had proved a very important point and that is the fact that this gas which we call inflammable gas is actually present in water you will know today that the formula for water is H2O but you try finding that out and proving it that's what love was here and scientists of his day used to do now this experiment Lavoisier first did this experiment in a gun barrel an iron gun barrel and that's why it's popularly known as the gun barrel experiment The Gun Barrel was made of steam and now you see the iron is now beginning to become red hot so I am now very carefully please excuse me Andres I just need to come around I am now going to connect this up and steam is coming out here quite rapidly I have to be very careful not to burn myself and now we connect this out so now what we've got is steam is beginning to go over the Red Hot Iron now shortly you will see Bubbles and here they are you must excuse me I'm just going to put another Gauntlet on as you can imagine this is all very hot indeed and I'm going to just put another dauntlet on and put this over here so what I'm hoping to demonstrate for you you can by the way see a little bit of a leap here but that's okay we can manage that remember these experiments the high temperatures which are required for these experiments they do a lot of damage to apparatus and cork usually Burns I'm just going to put this in a little bit more firmly now just a little more firmly and you see this bubbling here now if we can show that this is hydrogen then that will be able to have shown to you chemically that the water contains hydrogen inside it but then you see what's happening to our eye and the nails that's the question the iron nails were inside we'll have a look at those afterwards but what you will see is the iron nails they change color they go from a nice silvery color which you see was our steel tube it's a steel tube which is basically iron but when they've reacted with the water vapor the steam at that very high temperature there we've got a temperature there of about 600 degrees Centigrade it's bright red heat then those iron nails are no longer shiny they will have a black color and that black color dear children is iron oxide it's an oxide of iron because the iron d decomposes water into hydrogen and the oxygen combines with the iron to make iron oxide now we're having a wonderful result here this is going extremely well thank you very much Andres and you see the huge amount of heat energy that's being supplied we will shortly I'm going to fill I'm going to take this one off now and I shall shortly ignite it but we'll wait for just a second I will do the other one and Andres once this has filled up to about a quarter or a half I will ask you to kindly switch off everything and disconnect the apparatus and then we'll want to tip out the nails once it's cooled down to show everyone the nails which were placed inside the whole tube is full of Nails by the way and we have to make sure that those nails and you'll see the ones in the middle because the whole tube is full of the will have turned back now Andres that's brilliant if you could kindly turn off the burners now and the boiler as well disconnect the apparatus now allow me quickly to show you disconnect it yet first of all just very carefully thank you so much indeed you have to disconnect the tube that's right now allow me to show you once again hopefully you will see that this hydrogen here will burn with a quiet flame with a very quiet flame as we did this should be pretty pure hydrogen and we listen do you see very purified this one though I'm going to do my favorite trick and that's empty the water out and we now have a mixture of hydrogen and air now with a bit of luck this will now make us squeaky pop so I'm going to now take this off you see listen carefully and once again you see and once again you Splendid demonstration now why is that happening and why is that difference occurring I'll explain that later on but now I just wanted to show a more modern technique for making hydrogen which we can make very rapidly indeed using a metal of course and this metal will also this metal will also break the water down but it's quite a bit more spectacular and for this purpose I'm going to ask for the light to be turned off but not just yet but not just let allow me to explain in this in this container here I have the metal calcium calcium is a very reactive metal and it was discovered at the Royal Institution by the great chemist Humphrey David by the process of electrolysis which I'm not going to go into and calcium reacts with water because it's a very reactive metal it's called an alkaline earth metal and it reacts with water very vigorously indeed and what I'm going to do job that would be fine Andres what I'm going to do is to sprinkle some calcium granules into this water and you'll notice they will start bubbling and as they bubble they react with the water to decompose it to release hydrogen gas here it was red hot iron here we're going to have cold calcium and as I now sprink now I'm going to sprinkle in quite a few drops quite a few pieces voila and now I've noticed the bubbling now can I have the lights Switched Off please yeah and I'm going to light the hydrogen let's see what happens and there you see a splendid flame of hydrogen burning on the surface of the water and it's burning with an orange flame you see this is the calcium red brick flame which we associate with a the element calcium and you'll be seeing more of that later on so there you see hydrogen released in this end you notice a lot of steam this reaction by the way is highly exothermic we could still occasionally light bubbles but their reaction has essentially finished so could we have the lights back on please now in the meantime you see the water has become turbid it's got white color to it there's a white precipitate formed in here and that is a precipitate of calcium hydroxide so when the calcium has reacted with the water it has made calcium hydroxide which is barely soluble in water and which is as a suspension there it's strongly alkaline and it has now it will we could show its alkaline by pouring at a little Universal indicator for those of you who are you'll notice that this will turn a very beautiful purple color a lilacadesh universal indicates you see and that's demonstrating the alkalinity of the water so just to show that it's a solution of count it's a saturated solution of calcium hydroxide in water Andres is now chipping out the nails it might take a little time Andres and please take care because they're still extremely hot now can I have the next slide please because I'm wondering whether what it is it's always it you know when I set these slides I um I don't know what the next one is I have an approx this is exactly what I wanted this is exactly what I wanted you see I have to tell you that a couple of weeks ago I walked into my bedroom and I noticed there was a magnificent fragrance there was a magnificent fragrance and I thought and I asked my wife I said have you spilled a bottle of perfume somewhere and it was there for two or three is this fragrance you see and I and I actually really was very nice indeed and said no she said I was given a present by one of my colleagues and it's a diffuser a diffuser I said no I know what that is and here it is here it is dear children this has a magnificent smell it has a magnificent smell I wish you could all smell it you see and the reason is it's called a diffuser I hope you've read what the slide says formulated the law of diffusion of gases so what is diffusion now for lots of students who find you know a lot of students they will say well it's a it said the diffusion is around the movement of particles in a manner which is independent of its external gravitational forces and during the fusion particles move from an area of high concentration to an area of low concentration and that's it you learn it as a definition and you don't understand it but it doesn't matter you see what I wanted to tell you is what I wanted to tell you is that um the fact that gases and it has spread out by themselves the this was amazing people used to ask themselves questions how is it that I'm standing in the bedroom there was no movement ah a lovely smell and you know yourself this phenomenon and you see people didn't understand that but at the beginning of the 19th century people used to understand that matter was made of Tidy particles this was a very very important advance in science that matter we can't see them but we know they are there and John Dalton formulated the atomic theory that particles are made of very at the tiniest particle of an element is called an atom which you can't break down any simpler and so forth that was 1808 and then they had the idea of atoms joining together in groups of two or more to make molecules and these were very important ideas from the beginning of the 19th century now then they said okay so we have atoms and molecules they're particles but then they said how can these particles they move they have to move somehow and that was you see and there were three states of matter this is the other very important idea in science since the beginning of the 19th century is that there are three states of matter solid liquid gas and this became a very useful way of interpreting both chemical changes and physical changes so in a solid they understood that the particles were close together and they vibrated in a liquid the particles were close together but they moved with some energy and in a gas the particles were spread far apart and they moved rapidly and this is exactly where this lovely smell comes from its fourth mortar movement however and this is the great Thomas Graham was one of the great Scottish chemists Thomas Graham said ah he said he noticed that some gases diffused quicker than others they were already studying at the middle of the 19th century they were investigating the physics of gases in addition to the chemistry of gases and it was noted that some gases diffused or moved quickly than other gases and he started conducting experiments with large numbers of gases and their rates of diffusion and he discovered that the rate of a diffusion of a gas is inversely proportional to the square root of its density now you don't have to remember that or even try to remember but in a very very simple language light gases diffuse quicker than heavy gases that is the most most basic idea of all and moreover why do they diffuse why do light gases diffuse more quickly and we have the X already then the explanation in terms of movements of molecules because the molecules move faster that was the simple explanation which was given then and then we investigated other factors such as temperature affecting rates of the fusion and so forth now I have a beautiful experiment which I wanted to show you here on diffusion because you see as I said at the very beginning hydrogen is the lightest gas in the universe now if you understood what I just said we could have the second one yeah over there but that will be later thank you very much sir that'll be okay um hydrogen hydrogen because it's the lightest gas diffuses faster than any other gas and there is a splendid experiment which I wanted to demonstrate here which which demonstrates this idea of diffusion and the fact that hydrogen can diffuse faster than the molecules that are made of air so there are two substances two gaseous or two airy form substances one of them is hydrogen which is the lightest gas in the universe we which I have in this cylinder here and the other is air now air is a mixture and it's very easy to remember I mean broadly speaking if you look at one hand and you say this is air Five Fingers of my air four of them represent nitrogen one of them represents oxygen air is approximately 20 percent oxygen and eighty percent hydrogen and therefore these molecules and by the way the nitrogen and oxygen molecules have a rather a similar density hydrogen is much lighter so in this experiment here I'm going to show you two experiments I am going to show the phenomenon of diffusion and how it can cause pressure changes to occur if one gas diffuses faster than another now what I have here is a device which many of you will recognize is called a manometer and it's a it's a tube which is full of water colored on one side but at the top of the manometer we have connected here a porous spot now excuse me I'm just going to show everyone now what do we mean by porous spot it's like a flower pot but the word porous means it allows molecules to flow through it molecules can throw flow through it and that means you can't literally blow into it and air will come out but over a period of time gaseous gaseous molecules will flow through this not only gaseous but also liquids and the ions and molecules of liquid what we're going to do now is we're I'm going to fill or our Andres will fill this with with hydrogen once this is filled and I'm going to do it upside down you see once it's full of hydrogen we won't know but we'll guess it's full of hydrogen I well can we do it over here please Andres I will move it over here I will then place my hydrogen over the um porous pot and very hopefully what will happen is the hydrogen diffusing quicker than air will start pushing the air out in there because it moves quicker and when it pushes the air out hopefully it will set up a pressure so let's try please Andres yes much more yeah this needs to have a very very generous supply of hydrogen and we can't tell when it's full but we guess we just have to use our okay I reckon keep going follow me follow me Andres right thank you very much that's it now let's watch let's see if anything happens anything happening I can't see anything is it has the pressure and you see it's forcing it's forcing the liquid up you see and it's forcing the liquid up because the hydrogen is diffusing through the porous spot and it's setting up a pressure and it's forcing the liquid in the manometer to go up this is by the way just colored water so we have a splendid demonstration here you see of um of the phenomenon of diffusion now I had an idea and which I had I had some remember of seeing something about this written somewhere of using this idea to actually have some fun with it you know scientists and teachers like to like to invent things to have a little entertainment with and I'm wondering whether any of you can predict what's going to happen here um I'm going to explain to you what I have I have got three small um three small containers here which are all porous spots they have a large surface area that's the sort of point that if you have three have the largest surface of the one large one and I have connected this and now I'm just going to raise this a little you must excuse me this has to be very carefully adjusted it has to be very carefully adjusted for height to a bottle which contains which contains colored water once again and a little area here where we can build up some pressure and there is a tube with a nozzle on it at the end I am now going to to repeat the experiment put the hydrogen fill this up with hydrogen and we're going to repeat the phenomena it will diffuse please please uh thank you very much on this let's get this full as much as we can as much as we can okay turn the pressure down gradually that's right that's right that's right and now let's see a fountain a diffusion Fountain you see and this is a remarkable demonstration once again of the way that pressure is generated you see the gas flows the hydrogen flows from an area of a rapid movement of a high energy molecular movement the air has less capacity to because its molecules are heavier and we have this beautiful Fountain now you see once I've taken it off that the air gets sucked back in again so I will just disconnect it there now you know what I had thought of this experiment uh when I was trying to invent a sort of interesting effect forever and then I turned to a book which I've got at home couldn't we have the next slide please um then this book the title of the book should be on the next slide and there it is and it's a very interesting title um air and its relations to life being with some additions the substance of a course of lectures delivered in the summer of 80 1974 at the Royal Institution of Great Britain this is where we are today my dear children and look at one of the experiments which they did can we have the next slide please dear children and their sir there it is exactly the same experiment so you're seeing an experiment which today you have seen here at the fusion Fountain exactly demonstrated by the way you might be interested to know what this kind of bottle is called with two Stoppers in it it's called a wolf bottle okay today they don't use these but you see they have wonderful application and there is a demonstration of it being used now we're going to can I just have the next slide I know ah there it is thank you so much that is exactly what I wanted to tell you I have now finished the topic we're going to be we're going to and forth with a variety of topics and I finished the topic of the Constitution of matter the idea of particles molecular movements motion and so forth thank you very much Andres and I am and I have explained to you a little about the three states of matter this is to do with matter but now we're going to and to something rather different and I'm sure that you know and this is the concept of light I'm sure you know that one of the great discoveries in the history of science was Isaac Newton's experiments in 1761 to split white light into its the seven colors of the rainbow the Newton's Prison Experiment prism experiment should I say now I might like to show you Andres who um who's a physics technician has actually that on the left you see you've got a like a beautiful diagram Andres is actually photographed the real living thing that's what Newton would have seen something like that he took a sun a sun raised from a distance obviously from from the Sun but through a slit in a dark room and he obtained that rainbow effect which you see beautifully Illustrated on the photo that's what you get in real life but you see this rainbow effect caused a huge amount of interest because people start to say well what's light made of and they they have various ideas and there were two ideas one of them is light is made of little particles with different colors which all flow together and the other idea was that light is made of waves today we call it electromagnetic radiation and those ideas persisted for a long time and I would now like to I have a specially flown over from Milan is a professor Fabio parramattiani who is now going to demonstrate to you something that we humans have known for many many thousands of years and it's been used in fireworks could we have the lights off please or are we ready not just yet not just yet Fabio please come in now Fabio has got Esky help him is a student who's very keen on chemistry and she's one of my assistants and Fabio can I hand over to you and ask you to explain what you're going to do thank you very much we can have made the lights down for this which is going to be a very simple experiment actually we're going to light just some solutions of chemicals dissolved in a flammable solvent you will see here the flame of the match and the light produced by those chemicals now this actually is another Sensational experimental fact it is known since very very many years from I would say maybe thousands of years if you put different chemicals into a fire you can get a different color from the flame but that was actually exploited by two great physicists by Gustav kirshoff and Robert Bunsen which is the same inventor of the Bunsen burner there to identify the elements because by looking at these different types of lights and passing through the passing that light to the Spectrum to the prism that Andrew just showed you you could decompose that light into individual frequencies into individual wavelengths and that gave rise to a lot of useful techniques analytical applications and ways to identify to tell the difference between the elements because for example if you look at these two last flames on my left side and on your right side they almost look identical to our eye but actually indeed they are different elements and they would produce a different pattern when you split the a light so this is actually quite beautiful to look at but also the connection with hydrogen is that physicists and chemists have studied the atomic emission spectrum of hydrogen and they learned a lot about how atoms work about quantum physics and all sorts of different sciences and Technologies just to let you know these chemicals are used of some of these elements are used in fireworks are used in pyrotechnics of course for the beautiful colors that they provide to the to the flame and in order from the right side you have lithium which gives a beautiful magenta crimson color strontium with a red dish more slightly reddish color calcium with orange sodium with the beautiful yellow that we recognize from Street lamps barium with the apple green lime green born beautiful the deepest grain you can get in fireworks still today copper bluish green and then rubidium and potassium which are very similar in color almost pinkish purple and that is what completes the Spectrum we can get colors from different elements and for many of the other elements we don't identify exactly by the naked eye the color but still these are the most beautiful ones and I hope this was an enjoyable sight to see how colors are made and what hydrogen led us to this color thank you very much uh I'm just going to thank you so much for the idea fabulous I wanted just to show the next couple of slides which reiterate what um what Fabio said but also a couple of interesting uh a couple of interesting observations you see Isaac Newton did his experiments with the seven colors of the rainbow in 18 1761 but in and but people and people were very interested to look at this rainbow of you know these these colors and various people started magnifying they looked at them through a very very carefully they had optical devices and they were able to look at these lights uh the the the seven colors of the rainbow and a German a German physicist whose name was fraunhofer he discovered that actually there were black lines there were lines in this spectrum and he said of the Sun the rainbow and there you have a a solar Spectrum that's from the Sun and with these thrown offer lines now he discovered several hundreds of them and he noted also their their wavelets or he noted made a made an accurate note of their exactly positions with which they occur and this became a source of great interest where do these lines come from what actually causes these lights well the answer is they are what are known as parts of the absorption spectrum of elements which are found in the sun in the vapor of the corona of the sun elements such as potassium calcium sodium and so forth and those elements were subsequently as Fabio said it was the German chemists and physicist Robert Wilhelm Bunsen and Gustav kirchhoff who in 1848 invented the technology or the technique of spectroscopy which is the analysis of colors which are produced by individual elements into discrete lines can we have the next Spectrum please you see here that as Fabio just told you two colors which looked identically red one of them was lithium and one of them was strong if you saw them they were at the end of the of the these the beautiful things we saw but you see if you analyze those flames and you analyze them and look at the wavelengths of the frequencies which is what this was represented We Now understand that waves are electromagnetic radiation then you see they have completely different appearance and yet to the eye they both seem to be red and that was the that was the remarkable um the discoveries of this analytical tool every single element if suitably irradiated will give uh will give um a a an emission spectrum of energy levels of the um of the electrons and this is the next bit I'm coming to because people said well where do these where does this light come from you heat it up how come you have these lovely colors and it wasn't until the end of the 19th century the beginning of the 20th century that people started to understand that the atom is actually made up of three of two particles initially it was just protons in that nucleus surrounded by electrons and then Chadwick discovered the neutron in 1932 but they started to understand that hydrogen being the simplest element that's the one that would be worth investigating because hydrogen had one proton and one electron and they were wondering what on Earth causes these lines when you heat up the hydrogen can we have the next slide please which shows you a hydrogen atom that's how in the simplistic way we can understand the hydrogen atom with a proton in the middle and an electron orbiting it now when you heat up hydrogen molecules of course hydrogen occurs in the molecular form when you heat it up then it starts to eliminates a radiation could we have the next slide please and you see that emanation it occurred in several series of lines but I'm just showing you part of the atomic emission spectrum of hydrogen and you can just see literally a few lines there and because there was one electron these lines lent themselves to mathematical analysis and people were able to relate and there were several sets of lines which occurred in different parts of the Spectrum which were not visible and by analyzing these lines a remarkable remarkable Discovery was made with the spectrum of hydrogen could we have the next slide please and this in a very very simple manner summarizes the discovery and it was made by Niels Bohr in 1913 he was a Danish physicist and he recognized the fact that the electron in the hydrogen atom can only occupy certain energy levels with respect to the nucleus and it orbits around like the the Earth orbits the sum but then you can if you energize the energy the nucleus then the electron can jump up a level it jumps up to a higher level and if you energize it more will drop up to another level but and this was the amazing thing there was nothing in between an electron could either be at one level or another level but not in between and that was the birth of the science of quantum mechanics today this is thanks to this idea of the fact that electrons in atoms can only occupy certain energy levels that today we have the whole Information Technology computers everything that we have the um mobile phones anything to do with information technology relies on our understanding of the fact is that electrons in elements can occupy certain energy levels but not other energy levels and that idea has been used also to explain chemical bonding and it's of universal importance but the point is hydrogen and the hydrogen Spectrum was the element that played the key role in this remarkable Discovery and now can we just have a look at the periodic classification of elements there and you see a beautiful periodic a hydrogen is number one element number one and they have Illustrated you see um hydrogen there in a a particularly uh in the middle in a larger than usual box but the point of that of course is so that people can see what the numbers stand for and that's not the object but I thought that this particular version of the periodic table it would be useful to remind ourselves because it shows that hydrogen actually is the most widespread element in the universe now that discovery that hydrogen is present in Stars I think something like 78 of the universe is made of hydrogen and this remarkable Discovery was made by a British American astrophysicist her name was setilia gapochkin Payne Cecilia Payne gapodkin and she was a brilliant astronomer and astrophysicist and in her PhD thesis she by the way she went to Saint Paul's girls school in Hammersmith not that far from here and she did her PhD in the United States of America and in her part of her thesis in 1925 she she put forward the idea that hydrogen constitutes the main element in the universe and that was not very well received however uh subsequent investigation showed of course that she was right and today this is a widely accepted theory of a Brilliance of a brilliant British American lady physicist so tertilia pain gapochkin that's her name and a indeed a very notable achievement now I'm now going to go on to something rather different can we have the next one and I wanted to talk a little bit about these balloons and the hydrogen now there is a slightly a cartoonish sort of um um a picture of Michael Faraday but the honest truth is you know that we enjoy igniting balloons full of hydrogen it constitutes the Mainstay of interest in chemistry lessons and it has been constituted the Mainstay of chemistry lectures and so forth because of its hugely entertaining value now you may not know that Michael Faraday one of the greatest chemists of all time and one of the greatest scientists of all time who was of course founded the children's lectures lectures of the Royal Institution in 1819 and for 40 years he was giving wonderful wonderful lectures to tune but he invented the rubber balloon that's the amazing thing he invented the balloon especially for children's lectures now the first balloon that he made certainly wasn't uh the first photo that he made certainly wasn't like today's balloons which you see behind me he actually had two squares of a thin rubber sheets he glued them together and he was able to inflate this with hydrogen much to everyone's Delight now what can I have the next slide please ah hydrogen of course I'm going to I'm coming onto Rockets now you see and everyone knows that very recently we had this remarkable the largest ever space rocket constructed and it's thrown to the Moon I think it's on its way back I'm not sure I haven't followed the latest but it's certainly a remarkable achievement but this is the important point I want you all to know is that hydrogen is used as a rocket fuel it's the most powerful fuel imaginable for um for firing rockets in in its liquid oxygen and liquid hydrogen combined together they make water 2h2 plus O2 makes two H2O that's the chemical and the remarkable amount of energy they release is used to propel Rockets into outer space now I today I'm also going to make some Rockets we're going to together with Fabio and uh yeah and and as you should be there and they'll have two teams but before I do the Rockets I wanted just to explain a little bit about hydrogen and the way it explodes I have three balloons here and they are all filled with something slightly different this balloon here is filled with pure hydrogen now when pure hydrogen you see when I pull it down it goes up like that you see it goes it's very very buoyant indeed you saw that at the beginning of the talk and when you ignite the hydrogen in a balloon like that it will burn with a dull fat that's the expression weaves it burns with a dull fat and that is why the reason why it burns an adult that is because it's surrounded by air and air only contains one-fifth oxygen furthermore the hydrogen is not actually mixed with the oxygen it's not premixed I'm going to ask for the lights to be turned off this is not a loud bang as I repeat it's a dull thud but it makes a beautiful orange flame as it burns and you can just see it as I put my flame to it here so that you see can we have lights back on please thank you very much now that was hydrogen nothing that I'm in a bit sorry now what is that okay Peter yeah now what I've got in this balloon here what I've got in this balloon here is a mixture can you see this one doesn't rise so rapidly this is a mixture of hydrogen and air so inside the balloon I blew it up first I went and then I added hydrogen to it so we've now got hydrogen and air which are pre-mixed now because they are pre-mixed they will burn much more rapidly and they will make a bit of a bang now if you're afraid of bangs the idea is to put your hands over your ears like this and but I say this is a louder bang this is a louder bang but it's still not the ultimate but I want you to see not only is there a bang but there is also a bit of a red flame couldn't we have the lights off please and you see thank you very much now can we have lights on please now you see that you see I think you will all agree that burnt much more rapidly but it didn't uh it wasn't exactly you know a super but it was certainly you could see the presence of the air which contains one-fifth oxygen this is the bintastic now in this balloon here I have a mixture and you see it's not too rapidly to rising of pure hydrogen and pure oxygen now this is um a mixture of hydrogen oxygen it's we don't know whether it's in stoichiometric proportions but this will and this by the way the French the French philosopher pilater de Rosier he used to call this Aria tonante which in Italian of course means Thunder Air this makes a very loud bang now once again hands over ears to make sure that you're not injured um and tonight and you'll notice this is a flash there will be no nonsense with orange Flames here just a bright flash and a loud bang and of course a small puff of steam so let's watch this one there you are so that and did you see it blew out the flame as well any any fool can do these experiments please this is the achievements of science notice it blew the flame out oh there now what I'm going to do now what we're going to do what we're going to do now is um a demonstration can we please do a demonstration of our own Rockets of our own Rockets now what I've got here are these are cardboard canisters and could be Fabio and SD please lined them all up there let me explain to you what's going to have off we're going to line them up four there and four there and we're going to be filling them with hydrogen now these by the way these can you see these beautiful colors these Rockets they were all painted by Nathaniel who's in the audience I gave him I gave him an exercise too I said Nathaniel I want to have some nice colors to show so this is what he's come up with and what I wanted to show you is this is how this works because I want you to understand what you're going to see and what is this this is a typical canister that's used for Pringles or some sorts of things like that you see and there is a plastic lid on it like this they all have a plastic lid and they've got a metal bottom to them now what we're going to do this is the important bit this plastic lid has a a fairly large hole in the bottom and the metal top has a very small hole I'll just expose it to you here you can see the small hole there now what's going to happen is we are going to fill each of these full of hydrogen we're going to yeah put the flame away thank you very much we're going to fill each of these with hydrogen and when we fill them with hydrogen it's it you have to fill it right to the brim and so one of us will be filling the other will be putting the lid on and the reason why we've got two teams of people simply you could do more in a short space of time and then once we fill them once we fill them then I'm going to ignite them and the way we do it is this we take the bottom one off first and then we take the top one off immediately and then someone and then we set fire to it so we've got a team of four people and these by the way when we have the Flames burning the flame will burn very quiet it's pure hydrogen pure hydrogen but this is the clever bits as the flame Burns so air starts to creep in at the bottom to replace the hydrogen the hydrogen goes out it's lighter and as it goes out more and more air more and more air until suddenly we have a critical mixture for an explosion and when that critical mixture for an explosion is Rich there will be an enormously loud bang and surprising for such a silly little piece of cardboard like this and then hopefully the cardboard Rockets will all take off and I don't know whether it will happen or not but I think we should try and spread them out as far as we can and so before we do this let me demonstrate the voice nonsense let me just demonstrate this for you now I have it running have it running we need quite a Brisk speed of hydrogen we have just a second just to say before before I do this just one more little demonstration with the physical properties of hydrogen hydrogen being the lightest gas in here also can make your vocal of chords vibrate differently can we have it on now now as I'm talking it has more hydrogen you know that my voice is higher my voice is higher I get that surprise thank you very much my voice was higher you know this is everyone does this but it's just a little bit of a demonstration of physics now antes Andres we're now going to do we're going to so we've got two teams of two people we're going to so I'm so uh I think the hydrogen should be running all the time and and we just simply are we ready to go then so have the hydrogen running at High Velocity have it running and then what you do keep it running high velocity and then as you pull it out Andres you pull it out pull it by the tube right and then we're doing the next one and then we do the next one oh it's already off okay so sorry I can't keep up the trick is you must feel it have it right up to the top then pull it out gently and as you fill it then you mustn't get any air in otherwise it'll explode where you light it which will be a terrible embarrassment so we have to keep filling and I'm sorry keep filling have a high pressure of hydrogen speed I specially brought a full full cylinder of hydrogen to make sure this doesn't let us down next one please next one please yes Andres next one yes he Berry is that okay are we okay yes yes please getting there okay next one have we done four have you done your one have we done all four one more I'll do this one okay you do that one I want you to have the fans right now the next thing is we're moving these around a little bit now we're moving them around a little bit take away the hydrogen cylinders and I do say the bangs occur very we want to have them spread out as far apart as we can had them spread out as far so down there around the corner because what happens is sometimes one sets off and now you want to have one person with a lighted splint one person with a lighted splint and the other one to remove the things now there will be no bang and until it takes a while but then you can start putting your hands over your ears as soon as we've ignited all of them do you know what we're doing did you so I'll think I'll show you the first one and then and then rightly you're gonna why not use a SP are you sure now you do the bottom one first bottom one first always the bottom one comes off first off here then top one off and now light it okay [Music] there'll be some bangs coming soon okay okay right bottom off here bottom off here yeah and the top one and the top one there just Chuck away the thing okay yeah and now bottom off bottom off top off okay light it are there light right now we move well away hands over but listen I'm going to carry on talking because the honest truth is um I can't predict these and while we're waiting for our Rockets to fire Rockets today they do make very loud bangs by they were so what's happening is the hydrogen is burning at the top in a very small nozzle air is going in through a larger nozzle and a critical point then you'll suddenly hear I think the Flames are all there I can't see them but I'm sure they're there and you'll hear a very loud bang now sometimes they all go off together sometimes they go off separately you really cannot predict this exactly the other there's the first one now sometimes they make a bank sometimes they don't it's a little bit of luck but I think you could see the effect and you'll see the lovely colors which are of these of these Miniatures there you are that one's like that you know sometimes as I say it's a loud bang sometimes it's but but you know the longer you wait the louder the bank oh dear that was so you see Rockets all over the place maybe this will be the loudest who knows but the point is I thought with eight of these it'll be smart for fun and I'm going to sorry sorry let's just wait for that to go I actually have to carry on my dear children while we're waiting for that one to go off I wanted to turn to my favorite subject which is food and um I wanted to and you might say well what on Earth what on Earth has heisen got to do with oranges and lemons is it possible that one wasn't ignited is it possible that it wasn't ignited let's let's I'll just carry on I think I don't think it'll go off but let the will you never know there's all sometimes a delayed reaction but the thing is we did have some fun that's the important thing and I hope you've understood the scientific principles because that it's still burning it's still burning that one was still burning it would go off down there Fabio it's still burning you'll hear a loud bang in a second now could we could we clear up the debris please if you could kindly clear up the debris I wanted to go on to my favorite topic which is food and you may say well what on Earth has hydrogen got to do with food now I'm sure I'm sure that everyone likes lemons and oranges you see and one of the things though which I'm sure you will have noticed is that lemons and oranges are slightly sour a slightly sour and you see and I wanted to tell you and something that you all know and I have no doubt you will not dispute is that lemons are more sour than oranges now the reason why an acidity this is to do with acid acid what I call what we call acid Behavior the idea of why are things sour is as old as humanity and this is where hydrogen as I will explain to you shortly hydrogen comes in so lemons are more sour than oranges we could tell that by taste but I have in here water with a few drops of this Splendid invention of the chemist and that is universal indicator and dear Andres could we move those beakers forward in that sequence because I will very shortly just in the same sequence because then we could show that thank you very much and I just wanted to show you how we can very easily show that lemons are more acidic than oranges so if I now take a nice piece of orange here and I squirt in some orange juice into my Universal indicator you know it's like it's about that much there and I give it a little swirl around let's see what color it changes and there you see you see it's gone you see it's gone orange now for those of you who know a little bit about Universal indicator colors that means that that is um weekly acidic you see but now I've got but you know that in any case because if I put some lemon juice in if I put some lemon juice in into this one here and that's roughly the same amount and give this a little swirl and you see it's gone red so this is quite a very interesting way see the chemist has invented Splendid waste analytical chemicals and Universal indicator is one of these which enable us to tell the difference between acids alkalis or strength of acids and strength of alkali and what I wanted to show I've done a very simple demonstration here is that I have in these six beakers um a very tiny amounts of different indicators the the chemists have enabled us to invent all sorts of remarkable substances and indicators are always great fun because they change color now these all of these have a few drops of a different indicator in them and they've all got a tiny amount of very dilute hydrochloric acid it's very weakly acidic just enough to to sort of to make it go colorless but in here in this jar here I have got the opposite kind of a substance to an acid and that's called an Alkali and everyone at school learns that acid plus Alkali makes salt plus water in a reaction which we call neutralization and we can detect if we do a titration experiment the color will change of the indicator when the solution is exactly neutral so I'm going to these I've got exactly the same liquid in here exactly the same but I've got different indicators that's the clever bit and they've all got slightly different colors and I hope that when I pour in my Alkali that these indicator colors we will become apparent and you see so there's our first one and as I pour in it's the same liquid but every time we're producing a different color you see and that's the remarkable thing about where hopefully a different color maybe I got whoops I've run out and now I do have Andres could you bring me the sodium hydroxide uh in the sodium hydroxide there is a flask of it uh somewhere I I do apologize I'm slightly running out of these things but the point is these indicators they have these wonderful different colors and just for your information that I've got three indicators here um phenolphthalein which you'll have heard of thymophthalane and paraffin or paranitrophenol thank you so much indeed so this is less elegant but it'll do the job hopefully now let's see what color we get this and there you see and this one we get here you see so we have a very nice selection of colors I'm sorry the Green's not too brilliant but you can see the point now I didn't invent these experiments they're a wonderful chemistry teachers and people who plan experiments to make them interesting and they and they um have developed such an experiment so why is it acidic this is the point what actually makes acidity and there were a lot of theories people wondered what is it about an acid that makes it acidic well Humphrey Davey in 1817 thought it was just hydrogen hydrogen gas of some kind the um the love was here the great French chemist Lavoisier said it was was oxygen in fact the word oxygen comes from the ancient Greek words Oxys and Genesis means The Giver of Life to acids um in in German today oxygen is called sour stuff sour stuff means the sour stuff so still at the root of that is comes of this idea of acidity now the um the debate ultimately of what actually causes was so evolved by a great a great Swedish man of a chemist and his name was Santi arinos can we have the next slide please just very quickly now svante Arenas got the Nobel Prize in 1903 once again when he did his PhD thesis and he suggested that um the um and suggested that uh the um water can split into electrically charged particles people just thought that was ridiculous they didn't believe him they couldn't understand how a neutral particle could split into two electrically charged particles but he was proven to be right he was proven to be right that's where he got the Nobel Prize and today we understand that water molecules can split into half can we just have this not too identical half they can split into hydrogen ions and hydroxide ions and pure water has equal concentrations amounts of these but water with an acid in it has an acidic water with a substance which causes acidity will have a greater concentration of hydrogen ions than hydroxide and vice versa with alkalis and that was brilliantly this concentration of the actual concentration was brilliantly interpreted by the Danish chemist uh Sauron sorens and could we have the next slide please Soren Sorensen invented the pH scale and he defined the pH as the a logarithm to base 10 of the reciprocal of the hydrogen ion concentration now that's quite a mouthful but I have found out in the past that if you have friends and you want to impress them at a party how your scientific skills are good you should say to them do you know what PH is and they say oh it's that boring three wheeler I said no it's the logarithm to base 10 of the reciprocal of the hydrogenine concentration they will be so dazzled by your scientific expertise though you'll be just to sit around and say oh can you tell us more about this wonderful so there is the definition go and learn it children not only when you score marks on an a-level paper but you'll also be able to Dazzle your friends next one please and I think now ah and there is the pH scale those of you who have indicators and there's a pH 1 to 14 they're all calculated numbers from that formula I gave you by the way which is quite quite remarkable and those are the indicated Universal indicators and now can we have the next slide please and here we have the final we're coming to the grand finale my dear friends one of the things of the great honors of coming to the Royal Institution a place with a great tradition and hydrogen is certainly not the first time that's being debated today um the first time I showed you was the hydrogen diffusion in 1874. in 1910 Sir James Dua gave a special he was a brilliant in the Dua flask the vacuum floss uh Duo gave a demonstration of uh of the liquid hydrogen which he was he was an expert at cryogenics and he had made liquid hydrogen there is a wonderful painting of him outside with the apparatus there and in 1935 the brilliant organic chemist professor John Reed um gave her a lecture here it was in November 1935 and John the thing about John Reed was that it was not only a chemist he spoke summer he spoke he gave lectures in Italian in German he got his PhD in Zurich he was a chemist in Australia and did fantastic research on plant materials one of the most extraordinary calories and a brilliant specialist on Alchemy and the history of chemistry now in 1935 and John Reed was also obsessed with exploding hydrogen balloons now he had to find an excuse he gave a a lecture entitled uh he gave a lecture entitled um the musical Alchemist there was a Friday evening I think it was 11th of November 1935 and the musical outcomes and he decided he had Michael Meyer was the person in question who composed some cannons and fugues for which Alchemist used to sing but but John Reed had to find a way of getting music into it somehow because he loved music and poetry and everything so what he did was he got his um the musical Alchemist the AL Works were analyzed by one of his colleagues Aberdeen University and he wrote especially a special piece was written for a choir to sing while the hydrogen oxygen balloons were exploded and this is what um the um the words of it out of the the of the song our pre could I have the next slide please the words of the song it was called hydrogenesis there it is and what I thought to myself and what he did was he had one of his music colleagues from Aberdeen University to write the the uh the song and he had one of his and he had um and he had the choir he had the choir from Aberdeen University which was called the kimik choir now I thought it would be wonderful to try and repeat something like that so I have invited a choir from Highgate School the Highgate School consoles to come and sing for us today while and the composition which you're going to hear has specially been composed by a very very good friend of mine uh former people of Highgate School Dr Gray and Waterhouse he has specially written music to accompany the explosion of hydrogen balloons not one two but you you can count I've lost track but there are a large number of them so what we're going to do can I ask the choir under the directorship of Catherine Harrison who's the director of our choral music at Highgate school to require to align themselves rapidly because time is running out and I shall be most grateful and what we're going to do is uh we're going to if you could line yourselves up please I need to get my main prop I have an important prop here which I'm going to lift up as I should have a hammer somewhere oh if I don't have a hammer doesn't matter I'll just use this oh look the nails are falling out now so you can come and inspect the nails later but this will be our this will Whoops a Daisy please excuse me ah you've got the Andres you can do the ignition okay you can I'll I'll tell you when I'll tell you when you can do the ignition so listen where's the candle that's burning ah can we please bring it over here Esky thank you very very much indeed so the choir will shortly begin now where is our conductor ah here we are now let's just remind me so composer Dr Gray Waterhouse Highgate School consort hydrogenesis now now David you're sitting terribly close to that this is going to make a very loud bang if anyone is afraid this is going to be very loud indeed and I will definitely cover both is if you're afraid if you're not then you'll like a fool that you're like me you see you just simply take what comes but the thing is hopefully uh I think this one hang around they will sort of I think this one will set off this one there's a huge amount of preparation went into this but I very much hope it works so I I do this when when they finish this thing and then and then Andres will do the the thing when they do that okay so the moment they've put their hands over their ears that's what you liked it okay well hydrogenesis 2022 Edition shh HHH hhhhh s foreign [Applause] [Music] [Applause] [Music] foreign [Music] [Music] foreign [Applause] [Music] [Music] [Music] is [Music] good night so generous [Music] [Applause] [Music] no yeah [Applause] thank you so much thank you very very much indeed ladies and gentlemen thank you very very much indeed a huge round of applause [Applause] thank you very much everyone come forward please help us thank you very much thank you very much attention thank you very much

Channel: The Royal Institution

Views: 167,829

Keywords: Ri, Royal Institution, royal institute, andrew szydlo, science experiment, science show, chemistry experiment, andrew szydlo chemistry, andrew szydlo experiments, andrew szydlo royal institution, hydrogen, explosive science

Id: w2wi6T4P9-U

Length: 80min 29sec (4829 seconds)

Published: Thu Dec 15 2022