now this is a chemistry show and whether you like chemistry or whether you like science in general it's very important that you be observant so we're going to start with a test I want to know put your hand up if when you came into the lecture theater you noticed the two television cameras okay right well all of those all of you who put your hands up you're all wrong because there was one television camera so you need to check on your observation skills why is there a television camera here well there's a camera here because there's a camera here because Oxford University is going to make you all internet Stars this show is being filmed for iTunes so in due course you'll be able to see yourselves all on iTunes and I thought it would be a good idea since we're a nice friendly Bunch if we started off by I will count to three and then you're all going to have to turn around and wave at the camera and Shout hello from Oxford okay can you remember that hello from Oxford right do you like remember that see okay wait quiet quiet please so it's going to be one two three and then you turn around and Shout hello from Ox Wave Your Hands okay one two 3 hello well you you haven't got the idea at all people are meant to be hearing you in New York and buenz arez and Sydney and Toronto um and if you can't be more enthusiastic about this you might just as well get up and leave so I want a bit of oomph this time a bit of noise can you manage that okay so one two three hello from Ox better better so this this show is not going to be a magic show in other words Malcolm and I are not going to do something and say oh that was a bit of a surprise I bet you didn't know what was happening there and then move on to something else there are going to be no tricks and indeed we're going to tell you what the science is behind most of the demonstrations so when you leave today you should know more than when you came in uh you'll be a a better scientist but there is a saying in science don't try this at home lots of these demonstrations you won't have seen in your Chemistry classes at school and there's a good reason for that it could be that the chemicals are too expensive it could be that you need special specialized equipment but it could be and for some of the demonstrations it is that they are dangerous so please don't be tempted to rush home and try these in your bedroom or your kitchen or at the bottom of the garden you can ask your chemistry teacher about them instead and this is a nice peaceful demonstration I've got a colorless liquid here and a blue liquid here and all I'm going to do is to mix them and well it's produced a sort of nice green color um but that's not terribly exciting you've seen green colors before you've seen color changes before as well I'm sure so what we'll do is just put this on one side and we may come back to this demonstration a little bit later right I need three volunteers please um can you all make sure that you're allowed to be filmed so come on then second over there come [Music] on okay all right so um as Hugh said these are all experiments so I I need you to wear safety glasses yep there you go and then the the other thing is because of all experiments there is a potential that it won't work okay so that's why I've got these three volunteers to do this first experiment because it is known to be a little bit tricky so what I'm going to do is in the front here we've got a hot plate stir yeah we're going to stir it and what I want the three of you to do is each one of you take one of these um bottles here right so you can have C you can have a and you can have B and what I want you to do is so that the camera can see it so you're going to have to kind of come around at the front here I want the three of you to pour it in at the same time yeah come on then be brave right right sort of right to you so the there you go like make sure everybody can see you right so at the same time all I'll pour come on pour it in yeah yeah all at once so it's not very exciting is it oh wait a minute wait a minute so it's got so what color is it so it's blue sort of Bluey purple yeah does anyone know what that is a blue purple a Bluey purple yeah like what color is it now purple what color is it now right so what's going on here is what we call a clock reaction so it's a bit chaotic so we don't know exactly when it's going to change color but what's happening is we got the purple stuff there's there's two things in there they reacting together to make um c and d and then what compound C is actually causing the reaction to go faster so it's a catalyst but then as the reactions keep going because there's like 13 reactions going on at once and it then regenerates compound A and B which is why you got the color change so thank you very much volunteers can I have my glasses back um okay now if I tell you that this next demonstration one or two of you just one or two of you might not be able to see this demonstration can you see what it might re might depend upon any ideas no good idea but no okay I've got I've got a special chemical here and this is as you can see a very dark chemical so in order that you can see it properly I've got a white light and I'll just shine this white light through it okay so what color is it R yeah it's clearly red it's obviously red but it's actually also green if you look in the neck you can see and if you look at where the bubbles are you can see that this is green but it's also red now this chemical this is not a trick we don't do any tricks this chemical is actually really y really green and red at the same time okay now this raises two questions one of course is well usually red plus green makes brown so why isn't this stuff brown but the second and more interesting question is how can it possibly be red and green at the same time so it's not magic no so has anybody got any explanation for this how can it be red and green at the same time yeah yes no it's only a single chemical here there's not two chemicals there isn't a red one and a green one well the explanation is really quite interesting to what color are our eyes most sensitive green green at last somebody said green our eyes are most sensitive to green and if you believe that we evolved by um growing up many many hundreds of millions of years or hundreds of thousands of years ago uh in an area which was forested it would be very important that our eyes could see green because the trees and the grass around us would be green so our eyes have probably evolved to see green very well this solution here absorbs light and it absorbs blue light really really strongly and it absorbs green light a little bit so if I shine light through this if I shine white light through this and white light of course contains all the colors that our eyes can detect if I shine white light through this the blue light is absorbed very very quickly so I shine some white light through here the blue light is absorbed almost immediately and what gets through the solution is then red plus green and because our eyes are very sensitive to Green we see the green but if the light has to pass through a very large amount of solution so it has to go from one end of the solution to the other more and more and more of the green light is absorbed and eventually no green light is left and so what we see is red light so this solution is genuinely both red and green at the same time there's only one chemical that is red and green um and it's called d chromic Lally two color there's not very many chemicals that we know that are like that but this is one of the nicer ones okay let's come back to the solution that I started with you'll recall that uh this solution was there was originally a a colorless solution and a blue one and I mixed them together and they went green and now this has gone red um this is a quite a clever solution because this can do arithmetic this can divide by two let me show you so here is the the old Beaker and let's just divide this in two and they're different colors okay now there's no trick there isn't anything sort of stuck on the bottom of this that's reacting with this it's only one solution and yet it makes two different colors so you might think about that because we'll come back to this in a moment but uh it's Malcolm to yeah so can I have three more volunteers please come on man one more yeah come right so Tim again safety glasses just in case right PR for you where there you go number three right so what I've got in front of you each one of you's got one of these that's yours that's yours okay and that's yours what I want you to do is you're going to take the lid off this try to make sure it's as soft as possible right so you're going to take the lid off these and you're going to add these chemicals but I want you to all do it at the same time right and as you add the chemicals put the lids back on and then shake it and hold the lid in place cuz I don't want you to get anything on your skin okay so maybe it'll be there like let's see if youall put yours down there's yours there's yours there's yours all right don't all do it at the same time and hold it up so everybody can see all right 3 2 1 go all of it check it all in and then put the lid on and shake it up right so can everybody see what's happening yeah so what we've generated here is an example of what's called Cold Light okay it's coming so what we've got here is an example of what's called cold light or chemiluminesence so as the name suggests it's chemistry to make light and as you can see they're all different colors um the reason it's called Cold Light is if if these three touch it it's cold yeah there's no heat coming off it so normally if you the light bulb but it would also generate Heat at the same time so that's why it's called Cold Light Now can anyone think of an example where you would use this in real life glow sticks which we just happen to have here all right so so these are the same thing so what you got is a little violin side that you snap and the two chemicals mix and then you shake it and you get light so you ready to [Music] catch there you go you can all have one each right did you want to put them down right we we've not got any big ones left but we've got some little ones so we ready to catch some maybe maybe at the end yeah I'll just give them a couple right so I'll just throw these ones out [Applause] now right if you come and see me at the end yes cuz we've got to get on if you come and see me at the end got some more and you can get one then okay right so just going to move on to the next [Applause] thing right quiet please so qu Dam when you think of school teachers like keep it clean cuz remember we're being filmed when you think of school teachers what's the word that comes to mind horrible horrible boring can you think of some nicer things maybe all right so when I when I think of school teachers I think of one word and that's rich yeah you know they get all these school holidays they're always on a break and they get paid loads of money to look after you lot yeah so with bearing that in mind is there any school teacher in here that' like to give me a loan of 20 oh we've got a volunteer oh that'll have to do thank you very much you okay got the tong and I'm going to got an ordinary J cloth here and I'm going to soak this in the magic liquid and then we're going to see if we can set light to the JLo there we go and we can and it actually Burns really quite [Music] well but in the end in the end you can see it's not actually burnt and yet J cloths are made out of flammable material and that's really quite curious because you can you can feel what you what does it feel like it feels cold okay well that was sort of a bit of a failure in a sense wasn't it cuz it's more fun when things go wrong so let's try again we'll put it back in the same liquid and we'll use another match there we go and those of you near the front will actually be able to feel the heat so it's possible to make cold Flames but this is not a cold flame this is a hot flame this would burn me if I got too close to it or if I put it and so you can see it is sufficiently hot that it does actually eventually burn the J cloth there's a little burn there now burning a j cloth isn't much fun but hav we got something else we can burn oh we've got we've got A1 note so well that's disappointing is let's give it another chance it's not my money after all so why is it why is it then that the pound this this 10 pound note doesn't actually catch light what is it that's kept it yeah well the reason this doesn't burn and the reason that the J cloth doesn't burn is that the liquid that we've got here is a mixture of water and something that does burn something that's flammable so when we put that mixture onto the J cloth or when we put that mixture onto the 10B notee the water which doesn't burn keeps the water which doesn't burn keeps the 10B notes cool where the flammable material the burnable material evaporates off and burns around the1 note now of course if we keep on burning more and more of this liquid the1 note will get hotter and hotter and eventually it will catch fire um and couple of years ago I managed to almost destroy 20 of a Primary School's teacher a Primary School's teacher 20s that belong to a primary school teacher um but fortunately the number on the note was left and if you've got the number on the note you can take the remains of the of the the note back to the bank and they will give you a new one for it so it's yours is it yeah all right so now I'm going to do an experiment using hydrogen peroxide so hydrogen peroxide is essentially it's water with extra oxygen in it so it's very very oxygenated and sometimes it can be found in the body so the body has to deal with it yeah so what we do is we have an enzyme called cataly and if we mix these two together what you can see is all that extra oxygen go somewhere and it makes a big froth no it didn't mix very well which is why there's a bit of a mess of my Beaker but but you can get the point like it's it's actually just foamed up and all these bubbles coming off are actually oxygen right so we've looked at hot stuff so now before we get to the cold stuff sorry I messed up before we get to the cold stuff we got to go back to the this solution remember this was the divide by two solution and it's still able to divide by two two different colors so what's going on there's nothing stuck on the bottom of the beaker here uh there's no trickery involved but this solution knows whether it's been divided in half or not two different colors yeah what no any more suggestions yeah what am I doing here I'm mixing it with what air with air yeah the colored chemical here is something called an indicator now you've met indicators at school perhaps if you had acids and bases in your laboratory lessons but this indicator tells us how much oxygen there is in the solution and as I add as I add air to the solution what happens is it changes color and you can see when I've got a lot of air in the solution it's a green color if I now put this Solution on one side there is a reaction that goes on in the solution and that reaction uses up the oxygen it's a reaction between glucose sugar basically and sodium hydroxide and that uses up the oxygen in the solution as the amount of oxygen in the solution diminishes the indicator changes color and So eventually we go from green to Red to a sort of brownie color to eventually gold um and we can make this cycle of color changes work again and again just by mixing in some more oxygen right cold stuff now so who knows what ear is made up of like what's what's the airr Caro okay so what what we're going to do is we're going to cool the air down and we get this stuff I don't know if you can all see that probably not but yeah it's dry ice so what is dry ice what's actually made of right so what I'm going to do it's not water no look it's actually carbon dioxide so what I'm going to do is hopefully this is not going to fuzz up too much but I'll put it on here let's put this in here it's going to fiz yeah right so does anyone know what that smoke is apart for this stuff that's coming up from before SMY yeah do you know what that smokey is it's what coldness yeah but what what actually is it what do you think it's made of it's actually what's happened is because the car carbon dioxide is so cold that as it it's going straight from a solid to a gas and as it's doing that it's giving out its energy and what it's doing is it's actually so much energy kep it's freezing the ice the water in the air it's actually and this is an ice fog so carbon dioxide is quite bad for us because of the Greenhouse Effect and stuff so we won't dwell on this too much so what we will do is move to liquid nitrogen so so dry ice is about -78 this is about -60 150 all right so let's start with this rubber tubing so people at the front feel that does it feel like normal rubber tubing yeah happy with it yeah no tricks no so I'm just going to stick this in here we've got some liquid nitrogen so what do you think's going on here right so what's happened is because the tube was hot as it hit the liquid nitrogen it's actually the tube's Frozen it's given enough energy for the nitrogen to come off we're getting water Vapors again and what's it done to this piece of rubber it's cold well apart from being cold Frozen so it's frozen yeah so look yeah it's actually of rock hard now if we if we leave that to warm up I'll get these guys in a couple of minutes to feel it again and you'll see it's returned to normal so let's use this banana all right so this is going to take a while to freeze so I'm just going to put it in there for a while and leave it and hope I can get it back out so something a little bit more dramatic we'll take these flowers so what do you think's going to happen to them right we'll freeze them and see what happens it's like being in Harry Potter right whoops so touch it so the difference between a living thing and like a bit of rubber is the fact that this is made up of cells and inside the cells there's water so as it freezes the water forms ice which punches the cell walls and that's why it goes all brittle and like there's nothing we can do about this now it's uh gone yeah [Applause] so moving on to a balloon what do you think's going to happen to this balloon it's going to [Applause] pop so what happens to the air when it freezes does it get bigger or smaller well let me put it in you can see cold so what happened to it it got smaller didn't it but look as it's warming up it's getting bigger again so what's happened is the Air's Frozen and become a solid which takes up less space than the gas so why do you think it's a trick because what so what happens to you when you get cold you go Blue n fair enough you're too smart the other one's in here yeah but you can see that it has shrunk it just it took a couple of minutes to get it to shrink and as you can see is I'm waving it around my arms blowing it up yeah it's getting bigger so we could do this like loads and loads of times the only problem is of course is the fact that this is made of material and as it gets stretched and relaxed and stuff it can start to sort of get holes in it so you couldn't do it forever but you could do it at least 10 20 times right let's see where the banana is well I'm just going to use these CU I don't want to put my hand in here because it is quite cold to say the least so like whoa it's very cold but as you can see it's completely and utterly solid so if we come up if you come up at the end what you'll see is if we open it up as it's become more like a smoothie cuz like you said the cell walls have all punctured and stuff and finally going back to our tubing it's still cold but it's more so it's gone back to being bendy isn't it see look I just so you can't make it bang anymore so so that's why materials can get hot and cold whereas we can't um Lisa dial next yeah do do you want to do that sub oh you want okay scientists scientists like to get rules they like to categorize things they like to observe experiments and then draw deductions from them and I want to tell you now about a really remarkable thing that happened many many years ago long before any of us were born there were some scientists looking at all of science knowledge and you'll be aware from school lessons that there are some bits of science that are fun and there are some bits of science that are a bit dull there are some that are difficult there are some that are easy and that are easy and so on and these scientists looked at all of this h huge array of scientific knowledge and noticed that there was a great big collection of science that was really really dull and so scientists wanting to categorize things said we're going to have to give a name to this area and so they called it physics and so what I'm going to do is I'm going to teach you a very small amount of physics there's a little laser here and all I'm going to do with this laser is try to put the laser beam into this piece of plastic tubing this is a hard piece of perspect and you can see that it's Hollow but there's a little Notch cut out of the top here and I'm going to try to get the laser beam into the Notch and you can see that when I do that the laser beam goes around in a sort of spiral so what we're doing here is bending light you might think that light goes around only goes in straight lines but in fact we can make light go round so the light is trapped inside the plastic it's not trapped inside the tube it's trapped inside the wall there now does anybody know how we use that piece of of knowledge well it's used in fiber optics fiber optics are the way that uh data from computers travels around the country and fiber optics consist of very very thin uh W wires very very thin uh filaments of glass and the data goes down the glass and it's trapped in the glass in the same way that the laser beam is trapped in that now if you think that piece of physics was dull this is even worse I should say actually physics is is fun uh malol and I are sort of quite critical about physics but there's an awful lot of nice science in physics so I've got here a small light source and what I'm going to do is just to swing this around and when I swing this around what do you know notice yeah the lights the lights's going on and off now why is it doing that well it's going on and off because this light is plugged directly into the mains and you'll probably be aware that electricity in this country is called AC current and AC current changes its phase many many times you probably don't know what a phase is but it's it's a bit like the electricity sort of switching itself off and on many times a second so if you to get yourself a digital camera and you had your science teacher have one of these things and they cost about 4 p and he or she was to swing it around like this at one revolution per second and you got your camera and you exposed for one second then you would see one complete circle of light lots of little dashes and by counting up the little dashes you could work out what the frequency was of the mains light so as I say physics actually does get more interesting than that but we thought we ought to have some bit of physics in there right so all the experiments we've showed you so far are experiments that give out energy so I'm going to show you one where actually it takes in energy so what we've got is a a metal uh sorry you got a metal container on top of a block of wood yeah and what I'm going to do is add this chemical to it and give it a bit of a St hopefully this is going to work it's probably not going to work you might you might need to have the uh more of it in there yeah okay so while Malcolm is doing that there is going to be one last demonstration for which I need a single volunteer uh and it's you at the back there yep oh you yes okay I shouldn't have chosen somebody right in the middle of a row should I oh I've already got one what hi what's your name jelle Jazelle yeah okay are you right-handed or left-handed right-handed okay this is jelle she's right-handed and what she is going to do in a moment once malcol has had a go with his demonstration there is jizelle is going to play around with this now this is our cattle prod and what she's going to do is to you'll find it very heavy so you'll need to support it with your left hand like that she is going to uh if you press that black button there and hold it down what she's going to do is to pass a substantial current through a little wire at the end here and eventually that little wire is going to get red hot so what should we do with it okay so what she's going to do you could you let go that for that for a moment what she's going to do is to do a test once Malcolm has finished with his stirring so what it's done is it's frozen there's a little bit of water underneath as one of the people in the front said and what it's done is it's actually Frozen it to the brick so you can't lift it so look I mean it can't come off that's why I can lift it like that and you can actually do this in such a way that you could get it so it's strong enough to actually if if hu was feeling strong you could lift me on that blocker would because I would be stuck to no chance anyway okay so this is the final demonstration and jelle is going to see if she can determine what's in these balloons okay so somebody said a any other ideas well there are various possibilities those of you who those of you who suggested air have been watching too many cartoons where a cartoon character blows up a balloon and it gets bigger and bigger and then eventually it floats off that's not going to happen with air because of course there's nothing to make the balloon rise so this is probably helium or it could be hydrogen and the way that we're going to test that is gazelle's going to get that really nice and hot and when it's really hot what you need to do is to touch the end somewhere about there so you press the button and keep it keep it away from the balloon to begin with and wait until it's really really sort of glowing nice and red and I'm out of the way right go for it we got the scissors so what do you think it was then okay so that was a bang but not really a very good bang and the reason for that was because the gas let me get I do the lightss got to do fine right okay so jelle's really getting into this now um so what we're going to do now is the helium was a bit sort of disappointing really so instead of having another helium balloon this one must be hydrogen because we know that hydrogen is lighter than air uh but the good thing about hydrogen is that it burns so what we're going to see now is whether this Burns and Malcolm's just going to put the lights down a bit just in case we uh have difficulty in seeing what's happening so that again needs to get really really nice and hot and when it's really hot just touch it to the balloon hot yet maybe just you put the lights down now because it takes a while to now you you might have thought that that was a bang you might have described that as an explosion but in fact it wasn't um it was really just a very rapid burning reaction and what happens what happens is that the hot wire sort of makes a little hole in the balloon and then the balloon kind of unwraps to leave a ball of hydrogen and then the hydrogen Burns and so what you get is a flame so it wasn't really an explosion it was just a bit more interesting than the helium so in case you were asleep with that one uh J is going to do another one this is the same and so what I want you to do is to look and see that it really is a flame as opposed to an explosion [Applause] that a bit more vigorous yeah you're going to get some a what so so you see that although there was a bit of noise there although there was a bit of noise there uh it wasn't really a bang it was just a kind of a WP and there was a lot of float if we wanted to make a proper bang then what we need to do is not to use the oxygen that's around the balloon but to put some oxygen in the balloon and just by chance we happen to have a balloon that's got some hydrogen and some oxygen in now this ought to burn more rapidly but it's quite difficult to get the mixture right uh so this may be a complete flop we've already seen one complete flop with the burner maybe this is going to be a complete flop as well but just in case there is a bang you've got to do two things okay so be quiet so you can hear me just in case there's a bang you've got to do two things okay the first is you're going to have to put your hands over your ears all right but if if you do it now you won't hear the second thing so wait all right so you're going to have to put your hands over your ears and the other thing that you have to do is to open your mouth the reason the reason that you need to put your hands over your ears of course is obvious because if there were a shock wave uh then especially the people who are foolish enough to sit at the front would would get their ears ringing and you open your mouth because you may know that there's a connection between your ear and the back of your mouth and so if there were a shock wave then if you've got your mouth open the shock wave will reach your ears both that way and through your mouth at the same time and your ears won't ring the [Music] other quiet please come on Qui and down come on calm down now uh fine volunteer here is going to have ear protectors on and they're very good ear protectors so she won't hear anything else uh the rest of us have to do as I say hands over your ears and mouths open having your mouths open is great because it makes you all look like fools but only I can see it the camera is not going to see it and Malcolm's going to have the lights off so hands over your ears and mouth open okay everybody you included hands over your ears mouth [Music] [Applause] open there's another one [Music] Okay so we've got we've got to get rid of these balloons so here's another one same thing hands over your ears mouths [Music] [Applause] open that was L that's it thank you