25 Chemistry Experiments in 15 Minutes Andrew Szydlo TEDxNewcastle

the science of chemistry has disappointed many people it disappointed the Emperor of China in the air 59 BC he had been told that one of his court officials Li yang could make gold a great feast was organized at the end of which li yang was to prepare a small quantity of the precious metal after toiling away with complicated apparatus for several hours all he succeeded in producing was an unpleasant smell Leo sang was executed on the spot this true story reflects one of the problems which has confronted mankind since the dawn of civilization the problem being understanding how substances change into different substances this phenomenon of substance is changing into different substances has now evolved into the grand science of chemistry so what is chemistry chemistry is the science of substances and how they turn into different substances and very frequently we can recognize a chemical change because there is a change of color as I pour my chemical water from one full asking to another you will notice a color change and this is because I am making a new substance on every occasion chemistry plays an important a hugely important role in our everyday lives masses of substances and materials that we use on an everyday basis Oh their existence thanks to the science of chemistry plastics polymers dyestuffs detergents perfumes toothpaste pharmaceuticals fuels explosives a whole range of remarkable substances tap water fizzy drinking water masses of substances fertilizers Oh their existence thanks to the science of chemistry chemistry the science of substances and how they turn into different substances now here I've showed you some experiments with chemical waters and I've Illustrated for you the principle of what can be stories about substances changing into different substances I'm now going to move to a different type of water which I have in my container here this type of water which is by magicians called magic disappearing water I will pour some into my beaker here and I will now throw it into the air and show how it disappears and I will stand under it there and don't look for it you won't find it and the reason is it has disappeared into thin air why has it disappeared into thin air because that is what it is made of this liquid which I have here represents one of the greatest triumphs of the science of physics physics is the science of matter and energy and one of the greatest challenges of the science of physics in the 19th century was to be able to achieve temperatures which are low enough to turn the gases of air into liquids and what I've got here is liquid nitrogen and the liquid nitrogen has a boiling point of minus 196 degrees centigrade now as you see it's boiling away in my plastic bottle here and the reason why it's boiling away is because this room is remarkably hot compared to the temperature of the liquid nitrogen we here are at about 21 22 degrees centigrade liquid nitrogen has a boiling point of minus 196 which is almost as cold as you can get anywhere in the universe absolute zero the coldest temperature in universe attainable theoretically is minus 273 degrees centigrade now one of the golden rules when you have liquids which are boiling is never ever put them into containers which are tightly sealed well that's precisely what I'm going to do now and then I'm going to have these spray bottles here and I'm going to tightly put the stoppers on and I'm going to gradually put them into these dust bins here now the reason why you should never ever do this is because when liquids boil they undergo a huge coefficient of expansion by a factor of about 800 I have poured in approximately eight a hundred centimeters cubed of liquid nitrogen into each of these bottles and that 100 centimeters cube will expand into about 80 liters now these bottles have a volume of naught point 5 of a liter and therefore when that liquid nitrogen evaporates it will occupy about 80 liters it will generate a pressure of about 160 atmospheres now these bottles that very clever though they are made of brilliant polymers they will just simply not withstand that pressure and therefore they may explode they don't always explode but when they do explode the noise is really quite substantial and that's why for safety reasons I have popped them into the bins now that will continue to boil away you may hear very loud bang so please be warned but in the meantime I'd like to show a couple of fairly obvious experiments with liquid nitrogen the most obvious one being of course is to freeze some water water freezes at North degree centigrade and I will pour a small quantity of water into here and cover it with liquid nitrogen so there goes our water there and I shall now pour liquid nitrogen on it and that will obviously turn the water into ice now unlike the experiments which I did with my chemical waters when I mixed chemical waters which were coverless together and you saw a color change because a new substance was being made here we have a totally different type of effect you see there is no color change at all and that is because here we have a physical effect the two colorless liquids which I have mixed together are now changing their state they're changing one of them is changing from the liquid state to the solid state that is the water and the other one the nitrogen liquid nitrogen is turning from the liquid state to the gaseous state so here we have the three states of matter in one very straightforward experiment now as the liquid nitrogen content to boil away you may hear a slight crackling sound now this is because when water freezes it expands slightly and as it expands the crystals take up a greater area and they push a volume should I say and they push against one another and sometimes this may lead they'd set up enormous mechanical forces which which is what the crackling is about and sometimes the beaker may actually crack so we shall keep our eyes on this allow the process to continue and I can just hear the beginnings of a crackling sound now just top it up make sure we continue to freeze our water and I wanted to tell you that when liquid nitrogen was first made at the end of the 19th century it did set off an entirely new era in the in the history of Technology and that's liquid gas technology and thanks to that today we have frozen food we have a huge number of all sorts of effects that we benefit from among them of course are refrigerators now to continue them on that experiments are also the science of cryogenics to continue with our experiments with low temperatures these by the way approximately 5 to 6 minutes you'll hear the bangs so please be warned I'm now going to show you an experiment with a solid here we have a piece of rubber tubing and it's elastic the reason why it's elastic is because when you stretch it it returns back to its original shape now the reason why it's elastic is because I can hear the pressure being taken up so you may hear a bang shortly now the the reason why it's elastic from a thermodynamic point of view is because it's because it's very warm in here because it's very warm in here these molecules in here have lots of energy however I will now I will now place the rubber tubing into a liquid nitrogen and please observe carefully what happens as we lower the temperature and you'll notice this most interesting effect you see of a shower a shower which is issuing from the end of the rubber tube now why does this happen well it's for the same reason that the bottles are exploding in there and that is because as the liquid nitrogen boils fiercely when it comes into with a very hot rubber tubing so it's expanding almost as I said by a factor of about 800 that's boiling therefore pushes the liquid nitrogen out setting up a pressure 40 roots out there as you saw there we didn't have didn't have anywhere to escape and that's why the bottle finally gave way now let us inspect our rubber tubing which we have here and let's see what has happened to the elastic property it went in as an elastic solid but now you see it's no longer elastic and if I whack it well on this table please watch carefully then it will shatter into a thousand fragments now the reason why it shatters into a thousand fragments is because at high temperatures the molecules are all vibrating we have lots of energy the molecules of the rubber tubing have lots of energy so they're all going around like that but when you drop them until liquid nitrogen there is very little energy and so the molecules suddenly freeze they go like this they freeze solid I'm of course being silly but I'm in the straight an important scientific principle now I wanted just to show you here we've got just going to see in the meantime I just wanted to show you our beaker has indeed cracked there it is there's a piece of glass has fallen away from it and what that shows you is it just shows you the huge forces intermolecular forces which are set up when water freezes it freezes the molecules rearrange themselves to form an open lattice now here I have a beautiful balloon a beautiful balloon and why does it have the pressure it has pressure inside it because the molecules of nitrogen and oxygen in the air are moving around because they have lots of energy because it's very warm but if we reduce the energy by pouring liquid nitrogen over the balloon then you will notice a very very interesting effect so please watch carefully I'm going to pour the liquid nitrogen over the balloon and as you notice the balloon starts to contract and as the balloon starts to contract say you'll notice they're getting smaller and smaller and it takes a very very a shape which has no no II that there's no elasticity it has completely collapse now why is this well once again it's the same reason at the low temperatures at the story I think the floors cracking underneath me they were so everything's freezing all around but we're still alright please look carefully the balloon has now collapsed it looks very sorry for itself but if we are able to warm up a little bit by shaking it up throwing it up in the air in a very short space of time let's see if I can catch it I'm sorry it's escaping from me it's escaping and as you see it has been restored to its full shape now why is that because of the warmer temperatures the molecules have more energy and therefore they move faster and move more rapidly now let's just carry on on to my favorite topic which is fire this flame here represents this frame here represents one of the greatest traditions of the human race and that is of course our ability to make fire we know that in East Africa where the first ancient civilizations were a hundred thousand years ago people were able to make a fire and sustain a flame I'm now going to just show you how thousands ten thousand years ago for thousands of years flames burns like this this is a piece of cotton wool and you will notice it's a dreadfully boring flame it's just like why is that well because the cotton wool is surrounded by air air or it could change 20 percent oxygen it was only realized that air is a mixture of gases about 300 years ago and we've been on this planet for a hundred thousand and mites chemists have discovered the oxygen is the vital component of air that makes things burn better they started either combining fuels with oxygen or mixing them with oxygen and here I've got a piece of cotton which has been chemically combined with oxygen please watch how differently this burns and how we butit is here how'd you notice and it's blown The Fray valve I knew it would blow the flame out damage that's adding an extra three seconds on to my talk never mind we shall quickly we're so quickly I was ready I have my mattress now what I wanted to show you I have shown you the world's first high explosive and that might Recinos or gun cotton I would love to do an explosion with it but I can't we don't have the time so made to show you a propulsion this here is a mortar it's a type of device which is used for I'm propelling fireworks high into the sky I'm not going to prepare firework I'm going to propel I'm a ping pong balls so sorry I got four ping pong balls in my pocket here I have a page cut guncotton cage here drop it to the bottom sorry hasn't gone to the bottom I don't know too bad I bet I don't force it to the bottom I'm sorry I'm struggling a bit against the odds and against time let me just there we I think it's got to the bottom if it hasn't too bad we're going to shove a fuse in there and that will hopefully when this goes off we'll see it going up to the will watch the ping pong balls fly out if they manage to reach the bottom if they didn't that's too bad will we then they won't we won't see anything but never they there goes our fuse hopefully come on catch fire time's running short theories Deary me this is a very bad piece of fuse so I'm going to have to put my fingers of lift and there we go now on to the final things here here we have there we are I don't know whether they went did anything happens yes they water now here we have sorry very quickly we have here we have here a balloon filled with hydrogen cause a complete sensation among scientists the lightest gas in the universe going off that's pure hydrogen this is thumb there are rialto lamp a a mixture of hydrogen and oxygen and now for my very fine work I have here a mixture of hydrogen and oxygen I have a fuse which I'm going to make here and this will be my final experiment and we're going to have a thunder and lightning effect here we're going to have found the rightly sorry everything is going mad let's just get rid of this balloon he's getting in my way now here we are I'm going to make up some flash powder some flash powder few spell that there this going to be so to summarize what have I been talking about chemistry what have I been selling to you chemistry in simple things simple and direct language chemistry for all so here we go fingers crossed and there it is so thank you very much thank you very much TV I wish you all the very best thank you for your kind attention thank you very much indeed thank you so much I did 15 seconds on the dot we're still in one piece I wish you very very best very very many Thank You Dean thanks

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