0:00:02 > 0:00:04Early alchemists wrote of a Fountain of Youth,
0:00:04 > 0:00:07and for centuries kings and explorers searched
0:00:07 > 0:00:09for this legendary spring that would restore the youth
0:00:09 > 0:00:11to anyone who drank from it.
0:00:14 > 0:00:16Does such a place even exist?
0:00:16 > 0:00:18And, if it does, what incredible elements
0:00:18 > 0:00:20might we find in its waters?
0:00:20 > 0:00:23Join us in the search for the Fountain of Youth.
0:00:41 > 0:00:44APPLAUSE
0:00:56 > 0:00:59Many people searched for the Fountain of Youth,
0:00:59 > 0:01:03but one of the most famous was the 16th Century Spanish explorer
0:01:03 > 0:01:05Juan Ponce de Leon, who spent his life
0:01:05 > 0:01:07trying to hang onto his good looks.
0:01:07 > 0:01:12And legend has it that he found the Fountain in Florida.
0:01:12 > 0:01:16Local people claimed this miraculous spring could even restore
0:01:16 > 0:01:19frail old men to perfect health
0:01:19 > 0:01:21and, incredibly, the spring is still there.
0:01:21 > 0:01:24On the screen now we can see the workers
0:01:24 > 0:01:28filling bottles from this Fountain of Youth
0:01:28 > 0:01:33And they've sent us a sample by airmail.
0:01:40 > 0:01:42Here we have our Fountain of Youth. I can't wait.
0:01:42 > 0:01:44Right, let's have a look.
0:01:48 > 0:01:50"It's on the shelf." OK.
0:01:50 > 0:01:54Right, so here it is. They've put it over here.
0:01:54 > 0:01:56So here is the Fountain of Youth.
0:01:56 > 0:01:58It really has come all the way from Florida
0:01:58 > 0:02:01which is quite exciting, but we need somebody to try it.
0:02:01 > 0:02:03Do I have a volunteer? Some hands went up...
0:02:03 > 0:02:06I'm afraid I can't give it to anyone down the front.
0:02:06 > 0:02:08You're far too young already.
0:02:08 > 0:02:10If I gave you this, who knows what might happen.
0:02:10 > 0:02:13We need somebody slightly more mature,
0:02:13 > 0:02:15slightly more advanced in years.
0:02:15 > 0:02:18I'm looking at the top, actually, and...
0:02:18 > 0:02:20Oh, yes, there's a chap right on the end.
0:02:20 > 0:02:22- What's your name, please?- Tim.
0:02:22 > 0:02:24Tim. And you'd like to try some of the Fountain of Youth?
0:02:24 > 0:02:26- I'll give it a go. - You'll give it a go.
0:02:26 > 0:02:28That's very good of you.
0:02:28 > 0:02:30I think we've arranged for some to be brought up to you.
0:02:30 > 0:02:32LAUGHTER
0:02:32 > 0:02:35Goodness me. Is it safe?
0:02:35 > 0:02:37DR WOTHERS LAUGHS
0:02:37 > 0:02:38Well...
0:02:43 > 0:02:47Don't drink it all! Save some for later!
0:02:47 > 0:02:49- So, are you feeling any younger? - Not yet.
0:02:49 > 0:02:53- Not yet? No wrinkles lost yet? - Don't know.- Don't know. OK.
0:02:53 > 0:02:57We'll come back to you later and see how it is going,
0:02:57 > 0:03:00but you were very good. You must be a chemistry teacher.
0:03:00 > 0:03:01You did ask, "Is it safe to drink?"
0:03:01 > 0:03:04You shouldn't be drinking in the chemistry lab, so well done there.
0:03:04 > 0:03:06Thank you very much.
0:03:06 > 0:03:08A round of applause for Tim for trying our water.
0:03:08 > 0:03:10APPLAUSE
0:03:14 > 0:03:17This year's Royal Institution Christmas Lectures
0:03:17 > 0:03:19are all about the elements.
0:03:19 > 0:03:21My name is Dr Peter Wothers,
0:03:21 > 0:03:24and I'm a Fellow of The Royal Society of Chemistry.
0:03:24 > 0:03:26The ancient Greeks thought
0:03:26 > 0:03:29there were just four elements that made up everything around them.
0:03:29 > 0:03:32These are the elements earth, air, fire and water.
0:03:32 > 0:03:36Last time we looked at the elements in the air,
0:03:36 > 0:03:40and tonight we're going to be looking at the elements in a glass of water,
0:03:40 > 0:03:44in fact, the water that Tim has just drunk, to be precise.
0:03:44 > 0:03:46To help me, we're going to be using our periodic table.
0:03:46 > 0:03:49Periodic table. Look at that. Excellent.
0:03:49 > 0:03:52Very good, everyone's here. Marvellous.
0:03:52 > 0:03:56We now know, of course, that we've got over 100 different elements.
0:03:56 > 0:04:01Together, we're going to see what elements we can find in our water
0:04:01 > 0:04:04and maybe we're going to find something quite miraculous
0:04:04 > 0:04:07in our glass of water, the water that Tim's just drunk.
0:04:07 > 0:04:12OK. Right, I need to put on my coat, ready for action now.
0:04:12 > 0:04:14So, thank you, periodic table.
0:04:16 > 0:04:18Excellent. Oh, you're so well-trained, really! Excellent.
0:04:18 > 0:04:21That's perfect, look at that.
0:04:21 > 0:04:25So, our periodic table, we saw that there's over 100 elements.
0:04:25 > 0:04:29And yet, water, of course, isn't one of these elements. We know this now.
0:04:29 > 0:04:33But this was only first realised about 200 years ago, just over.
0:04:33 > 0:04:39So, why was that? Well, partly because nobody had ever done this.
0:04:41 > 0:04:42BOOMING EXPLOSION
0:04:42 > 0:04:44ALL GASP AND GIGGLE
0:04:44 > 0:04:46Well!
0:04:46 > 0:04:48That seemed to bring the house down!
0:04:48 > 0:04:50APPLAUSE
0:05:02 > 0:05:04That was certainly rather dramatic!
0:05:04 > 0:05:07But what we actually did there is just make some water.
0:05:07 > 0:05:10The balloon was filled with hydrogen...
0:05:10 > 0:05:13which, of course, when we light it...
0:05:13 > 0:05:16combines with the oxygen from the air...
0:05:16 > 0:05:17to form water.
0:05:19 > 0:05:22OK. Now, that was rather violent,
0:05:22 > 0:05:25and we couldn't see any of the water that we made
0:05:25 > 0:05:28because as soon as it was made, all that energy that was released there
0:05:28 > 0:05:32vaporised it and disbursed all the droplets into the lecture theatre.
0:05:32 > 0:05:35But we can do this in a more controlled way,
0:05:35 > 0:05:39so we can actually see some of the water being formed.
0:05:39 > 0:05:42And, well, this is the apparatus that we're just bringing on now.
0:05:42 > 0:05:45OK, so...
0:05:45 > 0:05:48We're going to combine our hydrogen and oxygen
0:05:48 > 0:05:51in this carefully designed apparatus.
0:05:52 > 0:05:55And we're passing pure oxygen through this,
0:05:55 > 0:06:00and Mark is just going to pass me a tube with some hydrogen.
0:06:03 > 0:06:05And let's just light that. Ah, beautiful.
0:06:05 > 0:06:07It's very difficult to see this flame sometimes
0:06:07 > 0:06:10because hydrogen burns with more or less a colourless flame.
0:06:10 > 0:06:13I think there's a few impurities in the glass there,
0:06:13 > 0:06:16but you can see it's definitely lit, it's definitely going.
0:06:16 > 0:06:19I'm just going to insert this into the apparatus.
0:06:19 > 0:06:22I hope I don't catch fire to our little things there!
0:06:22 > 0:06:25There we are, look at that, beautiful, right.
0:06:25 > 0:06:26So, just insert this.
0:06:26 > 0:06:31In fact, as it's going in, the flame gets much hotter,
0:06:31 > 0:06:34because this is an oxygen-rich environment in this apparatus.
0:06:34 > 0:06:37And it's just beginning to vaporise some of the glass.
0:06:37 > 0:06:39And this yellow colour that you see now
0:06:39 > 0:06:42is excited sodium atoms from the glass.
0:06:42 > 0:06:45But I'd like everyone to keep an eye on this during the reaction.
0:06:45 > 0:06:47This is like our little Olympic flame.
0:06:47 > 0:06:51If this goes out, please let me know during the course of the reaction,
0:06:51 > 0:06:54I'm trying to generate enough water to maybe taste it later.
0:06:54 > 0:06:57We'll have to see, we're using very pure gases here.
0:06:57 > 0:07:01The important thing that we can see is that we've got our flame,
0:07:01 > 0:07:05it's clearly very hot, but we are generating water.
0:07:05 > 0:07:07You can see that this is misting up now at the top here,
0:07:07 > 0:07:12and we're beginning to get some water and it's dribbling down here.
0:07:12 > 0:07:16So this is actually showing us that water is not an element after all.
0:07:16 > 0:07:20It's made up of these two gases, hydrogen and oxygen.
0:07:20 > 0:07:24This, as we are forming these bonds here, is releasing a lot of energy.
0:07:24 > 0:07:26This is, as we're making new bonds
0:07:26 > 0:07:28between hydrogen atoms and oxygen atoms,
0:07:28 > 0:07:32forming our droplets of water, that are beginning to collect now.
0:07:32 > 0:07:36But I'd like to show you another reaction that clearly generates
0:07:36 > 0:07:40a lot of energy, a lot of heat as molecules are coming together,
0:07:40 > 0:07:44as bonds are being formed, and this one is quite miraculous.
0:07:44 > 0:07:46This is one of my favourite reactions,
0:07:46 > 0:07:48because it really does look like magic.
0:07:48 > 0:07:51What we've got here is a tube just of cold water.
0:07:51 > 0:07:55Everyone knows what temperature water freezes at, don't we?
0:07:55 > 0:07:57What temperature does it freeze at?
0:07:57 > 0:07:58- ALL: Zero. - Zero, exactly.
0:07:58 > 0:08:03So here it's coming, this is a test tube full of cold water.
0:08:03 > 0:08:04Thank you very much.
0:08:04 > 0:08:07- What temperature is this water at? - Minus three.
0:08:07 > 0:08:11Minus three, this one. So this is actually at minus three.
0:08:11 > 0:08:16And yet, of course, we know that water SHOULD be ice at minus three,
0:08:16 > 0:08:18and yet it isn't. OK?
0:08:18 > 0:08:22Now, watch what happens when I add just a tiny little crystal of ice.
0:08:22 > 0:08:26This is now freezing. OK?
0:08:26 > 0:08:31So you can see that this water is turning into ice.
0:08:31 > 0:08:34In fact, the ice is all the way down to here now.
0:08:35 > 0:08:39So we know that water should be ice at minus three degrees,
0:08:39 > 0:08:44and it is now becoming ice at minus three degrees. OK?
0:08:44 > 0:08:46In fact, let me see if I can actually turn this upside down.
0:08:46 > 0:08:49Can I do that? There's a little bit dribbling out,
0:08:49 > 0:08:53but there we are, it is in fact solid ice there.
0:08:53 > 0:08:56That's pretty impressive, I think. Let's hand that out, thank you.
0:08:59 > 0:09:01Now... How can we...?
0:09:03 > 0:09:05So, how can we do this?
0:09:05 > 0:09:08We need to be very careful, it's like trying to balance this pen.
0:09:08 > 0:09:11I was trying it with a pencil earlier and it didn't work.
0:09:11 > 0:09:13I can balance a pen on its end there.
0:09:13 > 0:09:15If we're careful, we can do this,
0:09:15 > 0:09:17but just give it a small jolt and it falls over.
0:09:17 > 0:09:20Now, we can really cool down our water very slowly,
0:09:20 > 0:09:23very carefully, we can get it to those temperatures
0:09:23 > 0:09:26if it's very, very slowly cooled, really pure water.
0:09:26 > 0:09:28But just give it a small jolt,
0:09:28 > 0:09:31it starts off this process of being how it should be.
0:09:31 > 0:09:34The question now is, what do you think happens to the temperature?
0:09:34 > 0:09:36Do you think it stays the same?
0:09:36 > 0:09:39Do you think it gets hotter, or do you think it gets colder?
0:09:39 > 0:09:42We're going to have a vote. So who thinks it stays the same?
0:09:42 > 0:09:45OK, quite a few. Who thinks it gets colder when freezes?
0:09:47 > 0:09:49Quite a few of you. And who thinks it gets hotter?
0:09:50 > 0:09:53It's a bit of a mix, I think. Let's see what happens.
0:09:53 > 0:09:55I need to take this very, very carefully.
0:09:55 > 0:10:01And here we can see that the temperature is indeed at -3.7.
0:10:01 > 0:10:04This is really pretty good,
0:10:04 > 0:10:06in this huge tube here.
0:10:06 > 0:10:08I might need some ice, but I'm just going to give this...
0:10:08 > 0:10:11Look at that, just moving it has set this off.
0:10:11 > 0:10:15Look what's happening to the temperature. It has shot up.
0:10:15 > 0:10:20It was at -3.7, it's now just... Well, it's actually,
0:10:20 > 0:10:24this top part is now above zero. And again, it's freezing.
0:10:24 > 0:10:26This is because as the water molecules...
0:10:26 > 0:10:29They were moving around in the liquid,
0:10:29 > 0:10:31but as they're locked into place in the ice
0:10:31 > 0:10:35we're forming bonds between the water molecules
0:10:35 > 0:10:36and the temperature goes up.
0:10:36 > 0:10:40That's really beautifully done, it's incredibly difficult to do,
0:10:40 > 0:10:43and I think we should thank Fiona for preparing this all day.
0:10:43 > 0:10:46Thank you, Fiona. OK, thank you.
0:10:54 > 0:10:57So the formation of bonds releases energy.
0:10:57 > 0:10:59This is a very important thing.
0:10:59 > 0:11:01Now, actually, we can show this in another way.
0:11:01 > 0:11:05If you look under your seats, you'll find a little hand warmer.
0:11:07 > 0:11:10Now, for those of you, of course, watching at home, I'm afraid,
0:11:10 > 0:11:13if you look under your seats, you probably won't find a hand warmer
0:11:13 > 0:11:16unless you remembered to put it there earlier,
0:11:16 > 0:11:17in which case, well done!
0:11:19 > 0:11:22OK, looks like people are finding their hand warmers.
0:11:22 > 0:11:25Your hand warmer contains a solution
0:11:25 > 0:11:28and it has salts dissolved in this.
0:11:28 > 0:11:30But actually, again, it's an unstable situation.
0:11:30 > 0:11:33There are more salts dissolved than there should be.
0:11:33 > 0:11:36So if we just give this a click, if you haven't done this already,
0:11:36 > 0:11:38you just click the little bit of metal in the corner.
0:11:38 > 0:11:40That's it, I can hear lots of clicking going on.
0:11:40 > 0:11:42That's just starting this reaction now.
0:11:42 > 0:11:45EXCITED CHATTER
0:11:51 > 0:11:55And it's resorted to exactly how it should be.
0:11:55 > 0:11:59We are forming bonds, the salts are precipitating out,
0:11:59 > 0:12:02and as they're forming bonds, forming the solid here,
0:12:02 > 0:12:05formation of bonds gives out energy and that's what you can feel.
0:12:05 > 0:12:10That's what's warming up your hands now, which is rather nice. OK.
0:12:10 > 0:12:14So the formation of bonds gives out energy.
0:12:14 > 0:12:17And that's what's taking place with our little flame here,
0:12:17 > 0:12:18our Olympic flame.
0:12:18 > 0:12:22I think we might just turn up the hydrogen a bit, lovely.
0:12:22 > 0:12:25So, here we are forming bonds between hydrogen and oxygen
0:12:25 > 0:12:27and that's releasing energy.
0:12:27 > 0:12:30And this is a really beautiful reaction here,
0:12:30 > 0:12:33because the only by-product of this is water.
0:12:33 > 0:12:36You may know, of course, when you burn petrol and other fuels,
0:12:36 > 0:12:39you get carbon dioxide, this is a greenhouse gas.
0:12:39 > 0:12:40The only by-product here is water
0:12:40 > 0:12:43and there's a lot of energy being released.
0:12:43 > 0:12:47So maybe this could be an answer to the energy problems of the future.
0:12:47 > 0:12:49Well, have a look at this.
0:12:57 > 0:13:00APPLAUSE
0:13:02 > 0:13:05This is Nathan Chang from Valeswood Fuel Cells Ltd.
0:13:05 > 0:13:08Nathan, can you tell us, what is this thing?
0:13:08 > 0:13:12It looks like a normal road bike. You can put it on the road, can you?
0:13:12 > 0:13:14It's a road legal scooter,
0:13:14 > 0:13:17but we put the fuel cell and hydrogen on there.
0:13:17 > 0:13:20This is lanthanum nickel hydride?
0:13:20 > 0:13:23That's a nickel metal-based hydride.
0:13:23 > 0:13:25- And it's absorbing the hydrogen... - Like a sponge.
0:13:25 > 0:13:28Like a sponge, and gradually releasing it.
0:13:28 > 0:13:30It's combining with the oxygen from the air.
0:13:30 > 0:13:32That's giving you the energy to power this bike.
0:13:32 > 0:13:35Yeah, that fuel cell generates electricity to power
0:13:35 > 0:13:38- the motor and power the vehicle. - OK, this is great.
0:13:38 > 0:13:40So you've just driven all the way through the RI.
0:13:40 > 0:13:42Haven't you polluted everywhere,
0:13:42 > 0:13:45is there oil dripping out of everything now?
0:13:45 > 0:13:48- The only emission is water vapour. - It's just water vapour.
0:13:48 > 0:13:50And the hydrogen comes from water.
0:13:50 > 0:13:52The hydrogen itself comes from the water?
0:13:52 > 0:13:54So you convert water to hydrogen,
0:13:54 > 0:13:57the fuel cell converts hydrogen to water again.
0:13:57 > 0:13:59So why don't we see more vehicles like this now?
0:13:59 > 0:14:03- Why don't we see more hydrogen vehicles?- Yeah.
0:14:03 > 0:14:05The hydrogen is still very expensive.
0:14:05 > 0:14:10And, also, you have problems to store enough hydrogen for a bigger vehicle.
0:14:10 > 0:14:12So you'd have to change your tank, would you,
0:14:12 > 0:14:14if you wanted to get back to Birmingham?
0:14:14 > 0:14:17- You'd need a bigger tank. - A slightly bigger tank.
0:14:17 > 0:14:19That tank can power this vehicle for 70 miles.
0:14:19 > 0:14:2170 miles, oh, pretty good then.
0:14:21 > 0:14:23So, if we could get a better source of hydrogen,
0:14:23 > 0:14:26- it would be cheaper, then we'd see more vehicles.- Yeah.
0:14:26 > 0:14:30- Because it's non-polluting, it only produces water, yes?- Yeah.
0:14:30 > 0:14:33Give Nathan a big round of applause, thank you very much coming in.
0:14:33 > 0:14:35APPLAUSE
0:14:40 > 0:14:42So we've got a bit of a challenge here.
0:14:42 > 0:14:45I mean, hydrogen could be the ideal fuel of the future,
0:14:45 > 0:14:49but the problem is, how do we get it in the first place?
0:14:49 > 0:14:53And one way that we can get it would be to break up the water.
0:14:53 > 0:14:56In fact, Nathan said that the hydrogen that they're using
0:14:56 > 0:14:59does come from splitting up water.
0:14:59 > 0:15:03But we can see that when hydrogen and oxygen combine to form water,
0:15:03 > 0:15:07this gives out a lot of energy. If we want to split up our water
0:15:07 > 0:15:10to generate hydrogen and oxygen, we need to put a lot of energy in.
0:15:10 > 0:15:14We can show this, this is another general thing of chemistry,
0:15:14 > 0:15:15that if we want to break bonds,
0:15:15 > 0:15:17we need to put energy into the system,
0:15:17 > 0:15:19and we're going to show this first of all
0:15:19 > 0:15:22by looking at interactions between water molecules.
0:15:22 > 0:15:25I'd like some volunteers from the audience.
0:15:25 > 0:15:26The back row, actually. That's it.
0:15:26 > 0:15:30- Give them all a round of applause. - APPLAUSE
0:15:36 > 0:15:38In this space, lovely.
0:15:38 > 0:15:41Hold up your balloons so everyone can see. That's it.
0:15:41 > 0:15:43Now, you're water molecules, OK?
0:15:43 > 0:15:45And at the moment you're bonded together
0:15:45 > 0:15:47to form the rigid structure of ice.
0:15:47 > 0:15:51So, of course, you're going to be wiggling around, gently vibrating.
0:15:51 > 0:15:52This is what ice looks like.
0:15:52 > 0:15:55But if we give them more energy, we can break some of these bonds
0:15:55 > 0:15:58that hold the water molecules together, and we get liquid.
0:15:58 > 0:16:02Now you can start moving around. Just have a little walk.
0:16:02 > 0:16:04This is our liquid. In fact, on the screen now,
0:16:04 > 0:16:07we can see this is a very complicated calculation
0:16:07 > 0:16:10carried out at the University of Cambridge from scratch.
0:16:10 > 0:16:13This shows what happens when liquid water molecules get together.
0:16:13 > 0:16:15They're jiggling around,
0:16:15 > 0:16:17but they are sort of held more or less in place
0:16:17 > 0:16:20with these dotted lines that you see there.
0:16:20 > 0:16:22These are bonds called hydrogen bonds.
0:16:22 > 0:16:24This is where the oxygen of one water molecule
0:16:24 > 0:16:27is slightly negatively charged, and it sticks
0:16:27 > 0:16:30to the slightly positively charged hydrogen of the other.
0:16:30 > 0:16:31Keep walking around.
0:16:31 > 0:16:35But what happens if we give you even MORE energy?
0:16:35 > 0:16:36They start separating,
0:16:36 > 0:16:39and we can get them to fly out into the audience here.
0:16:39 > 0:16:42This is where we're making steam, all right?
0:16:42 > 0:16:44- LAUGHTER - So lots more energy,
0:16:44 > 0:16:48the water molecules are separated, and we've got steam.
0:16:48 > 0:16:50So thank you very much, water molecules.
0:16:50 > 0:16:52Please return to your seats.
0:16:52 > 0:16:54APPLAUSE
0:16:58 > 0:17:01So, all we've managed to achieve so far, then,
0:17:01 > 0:17:05is pulling the water molecules apart from each other to generate steam.
0:17:05 > 0:17:08But this raises a very interesting question -
0:17:08 > 0:17:11how much more space does the steam now take up,
0:17:11 > 0:17:13compared to the water?
0:17:13 > 0:17:16So, in other words, if I took one millilitre of water,
0:17:16 > 0:17:19how many millilitres of steam would I be able to get?
0:17:19 > 0:17:23This piece of apparatus here is designed to try and show us
0:17:23 > 0:17:26how much steam we can get from one millilitre of water.
0:17:26 > 0:17:30And I need a volunteer for this one, please. Er...
0:17:30 > 0:17:31yes, actually, in the white.
0:17:31 > 0:17:34Would you like to come down to the front, please?
0:17:34 > 0:17:36APPLAUSE
0:17:39 > 0:17:42- OK. And your name is?- Connor. - Connor, OK, great.
0:17:42 > 0:17:44Do you know how many millilitres of steam
0:17:44 > 0:17:45we're going to get from 1ml of water?
0:17:45 > 0:17:47Have a guess. You've got a scale here.
0:17:47 > 0:17:49You're going to be looking at this scale.
0:17:49 > 0:17:52It goes from zero up to 100ml. How many do you think?
0:17:52 > 0:17:54- 50.- 50 ml.
0:17:54 > 0:17:58In the middle, OK. Who thinks more than 50?
0:17:58 > 0:18:00Who thinks less than 50?
0:18:00 > 0:18:01More than 50?
0:18:01 > 0:18:03- Yes?- 100.
0:18:03 > 0:18:04100. Any advances on 100?
0:18:04 > 0:18:07- Yes?- 150. - Well, if it goes past 100...
0:18:07 > 0:18:10150 is going to be past the dial. I want you to watch the dial.
0:18:10 > 0:18:13I'm going to squirt the water in this end.
0:18:13 > 0:18:16Here's my syringe. So this is going to be 1ml of water.
0:18:16 > 0:18:19I'm hoping that this is all nice and hot.
0:18:19 > 0:18:21So 1ml is not a lot.
0:18:21 > 0:18:24If you see, that's just 1ml there. and you think 50, don't you?
0:18:24 > 0:18:27And we've got all sorts of different guesses here.
0:18:27 > 0:18:31So, right, I'm just going to turn this tap and put this in,
0:18:31 > 0:18:34and I hope, fingers crossed, I squirt that in,
0:18:34 > 0:18:36close the tap, and there we are.
0:18:36 > 0:18:39Watch the thing. Let's see how far it's going to go...
0:18:39 > 0:18:42Keep going. 50... oh, it's gone past your 50.
0:18:42 > 0:18:43Still going. It's gone past 75.
0:18:43 > 0:18:46Can we turn this on actually? Is that possible?
0:18:46 > 0:18:49- To get this back up to temperature? - MACHINE WHIRS
0:18:49 > 0:18:52Ah, brilliant! Yeah, I can see it boiling now.
0:18:52 > 0:18:55So we're trying to get some heat back into this thing.
0:18:55 > 0:18:58- How far have we gone so far?- 225.
0:18:58 > 0:18:59- Sorry? How many?- 225.
0:18:59 > 0:19:01225. Who said 225?
0:19:01 > 0:19:02Oh, well done!
0:19:02 > 0:19:05- Well, we've gone past that now! - LAUGHTER
0:19:05 > 0:19:07Right, OK, it's still going. Got quite a lot of...
0:19:07 > 0:19:09look down this end, actually.
0:19:09 > 0:19:12Yeah, you can see the water in there.
0:19:12 > 0:19:15Yeah, still quite a lot. Oh, you've missed the dial!
0:19:15 > 0:19:16How's he doing? What's that?
0:19:16 > 0:19:18- 300.- 300, OK. Good, keep going.
0:19:18 > 0:19:21Still water there. It's still going, then. We're up to...
0:19:21 > 0:19:23- What are we up to?- 450.
0:19:23 > 0:19:24450, OK. Not quite hot enough.
0:19:24 > 0:19:28It's so difficult to do this. It needs to be SO hot.
0:19:28 > 0:19:29- Where are we up to now?- 650.
0:19:29 > 0:19:30650? We're still going.
0:19:30 > 0:19:33There's still quite a bit of water there.
0:19:33 > 0:19:36This is just our 1ml.
0:19:36 > 0:19:39OK. And this is now... Where are we up to?
0:19:39 > 0:19:40- 900.- 900.
0:19:40 > 0:19:43So quite a few people said...oh, is that 1,000?
0:19:43 > 0:19:45- Yeah.- That's 1,000, OK.
0:19:45 > 0:19:47Now, it's still expanding.
0:19:47 > 0:19:48We'll keep counting here.
0:19:48 > 0:19:53But this is actually really quite important, this expansion here.
0:19:53 > 0:19:56It's THIS expansion that drove, quite literally,
0:19:56 > 0:19:58the Industrial Revolution.
0:19:58 > 0:20:02It was the power here, as water is turned into steam,
0:20:02 > 0:20:05driving pistons, driving our machinery.
0:20:05 > 0:20:06How are we up to so far?
0:20:06 > 0:20:10- 1,375.- 1,375. Very precise!
0:20:10 > 0:20:12You're a keen scientist, I can tell!
0:20:12 > 0:20:14- Physicist.- Physicist! Ah!
0:20:14 > 0:20:16- Almost as good as a chemist! - LAUGHTER
0:20:16 > 0:20:19- Anyway, how are we doing now? This is coming up to...- 1,650.
0:20:19 > 0:20:221,650. OK, we're going to have to stop this now.
0:20:22 > 0:20:26There's a tiny bit there, but this is going to go to over 2,000ml.
0:20:26 > 0:20:31So, you're a physicist, and you said, what was it? 50ml?!
0:20:31 > 0:20:33Well, anyway, thank you very much.
0:20:33 > 0:20:36Give him a big round of applause for keeping track. Thank you.
0:20:36 > 0:20:38APPLAUSE
0:20:40 > 0:20:42So, we've converted our water into steam,
0:20:42 > 0:20:45and we need to put quite a lot of energy in to do that,
0:20:45 > 0:20:47but we still haven't actually made our hydrogen.
0:20:47 > 0:20:49This is what we were trying to do.
0:20:49 > 0:20:52To do that, to actually split apart the water molecules,
0:20:52 > 0:20:55we need to put even more energy into them.
0:20:55 > 0:20:58And, we're going to show this now with this apparatus.
0:20:58 > 0:21:01So we've got some water in the tubes here,
0:21:01 > 0:21:02and I'm just going to plug this in.
0:21:02 > 0:21:04So this is connected to here,
0:21:04 > 0:21:07and this is a generator.
0:21:07 > 0:21:09So if I hop on the bike,
0:21:09 > 0:21:15I should be able to drive the little generator at the back like this.
0:21:15 > 0:21:17We can begin to see some bubbles.
0:21:17 > 0:21:20It's quite hard work here, trying to split up the water,
0:21:20 > 0:21:23so I'm going to get somebody else to do all the hard work, I think.
0:21:23 > 0:21:26Actually, we need quite a lot of hydrogen,
0:21:26 > 0:21:28so I'd like you to welcome, please,
0:21:28 > 0:21:31Paralympic gold medallist, Mark Colbourne.
0:21:31 > 0:21:33Thank you very much, Mark.
0:21:33 > 0:21:36APPLAUSE AND CHEERING
0:21:37 > 0:21:40- Thank you for joining us. - Thank you very much.
0:21:43 > 0:21:47LOUD APPLAUSE AND CHEERING
0:21:51 > 0:21:53Some great warmth from the audience here.
0:21:53 > 0:21:55You've obviously done a fantastic job.
0:21:55 > 0:21:58Before you get onto this thing, tell us a little bit about yourself.
0:21:58 > 0:22:01You had an accident paragliding, is that right?
0:22:01 > 0:22:04I did, yes. May 2009.
0:22:04 > 0:22:06So just over three and half years ago.
0:22:06 > 0:22:09I broke my back in a near fatal paragliding crash in South Wales.
0:22:09 > 0:22:12So I was very lucky to survive, yeah.
0:22:12 > 0:22:15And clearly it's not affected your legs too much,
0:22:15 > 0:22:17since you can cycle so well!
0:22:17 > 0:22:20Yes, I've been left with lower leg paralysis.
0:22:20 > 0:22:24So both my feet don't work, so I have to wear special ankle supports.
0:22:24 > 0:22:28No hamstrings firing, no bum muscles firing, so it's all quads.
0:22:28 > 0:22:31There's pretty big quads there, so that's pretty good!
0:22:31 > 0:22:32- Now, this is what I'd like to see.- Yes!
0:22:32 > 0:22:36Being a modern alchemist, this is some gold, is it? Some real gold?
0:22:36 > 0:22:41Yes, what you have here is my very own Paralympic gold medal.
0:22:41 > 0:22:43That's fantastic.
0:22:43 > 0:22:46APPLAUSE AND CHEERING
0:22:50 > 0:22:52This certainly feels pretty heavy.
0:22:52 > 0:22:53Is this solid gold?
0:22:53 > 0:22:57No, it's actually 390g of solid silver,
0:22:57 > 0:22:59and then you have 22g of gold
0:22:59 > 0:23:02obviously coated around the outside,
0:23:02 > 0:23:05and, proudly, actually made in Llantrisant, in South Wales.
0:23:05 > 0:23:07Oh, that's fantastic. Really good.
0:23:07 > 0:23:10Nice to see a bit of gold in the studio, as well.
0:23:10 > 0:23:13I think we've got a picture of you here, just crossing the line.
0:23:13 > 0:23:15- How did it feel crossing the line? - Just euphoric.
0:23:15 > 0:23:18It was almost like Christmas and birthdays rolled into one.
0:23:18 > 0:23:21- And you got one of these, as well. Fantastic.- Very much so.
0:23:21 > 0:23:24But have you ever split up any water molecules before?
0:23:24 > 0:23:27- That's the real question. - No, not in this sense!
0:23:27 > 0:23:29Obviously, lots of sweat when I'm training.
0:23:29 > 0:23:31I think you need to give it a go.
0:23:31 > 0:23:34If you'd like to hop on. I'll look after this for you.
0:23:34 > 0:23:36OK, wonderful. Make sure he doesn't run away, OK?
0:23:36 > 0:23:37LAUGHTER
0:23:37 > 0:23:39Because I won't be able to catch him!
0:23:39 > 0:23:44Yes, so, now then, Mark's on this bike here.
0:23:44 > 0:23:48All his power is going to go into driving this little generator here,
0:23:48 > 0:23:50and this really is just connected
0:23:50 > 0:23:53to the water we've got in these tubes.
0:23:53 > 0:23:55OK, take it away then. That's great.
0:23:55 > 0:23:57So we've got two electrodes here.
0:23:57 > 0:23:59On the negative electrode,
0:23:59 > 0:24:02this is where the hydrogen atoms are collecting.
0:24:02 > 0:24:05So, remember, the hydrogen in the water is slightly positive,
0:24:05 > 0:24:08the negative electrode is giving them electrons,
0:24:08 > 0:24:11forming hydrogen atoms, and forming hydrogen molecules.
0:24:11 > 0:24:13On the positive electrode, the oxygen atoms,
0:24:13 > 0:24:16which are slightly negative in the water,
0:24:16 > 0:24:18are having those extra electrons ripped away
0:24:18 > 0:24:21to form oxygen atoms and, eventually, oxygen molecules.
0:24:21 > 0:24:24But the interesting thing here, as Mark's pedalling away...
0:24:24 > 0:24:26Go on, faster!
0:24:26 > 0:24:28The interesting thing is that we can clearly see
0:24:28 > 0:24:31that we're getting twice as much hydrogen gas
0:24:31 > 0:24:33as we are getting oxygen gas.
0:24:33 > 0:24:35So this clearly shows, then,
0:24:35 > 0:24:38that water is made up of twice as much hydrogen as oxygen.
0:24:38 > 0:24:40Oh, I think you've broken it! Go slower!
0:24:40 > 0:24:42Has it gone again? Sorry!
0:24:42 > 0:24:44Pretty tiring, isn't it? Don't you think?
0:24:44 > 0:24:47- Pretty tough. - Yeah, thank you very much.
0:24:47 > 0:24:49I think a big round of applause there for Mark.
0:24:49 > 0:24:52APPLAUSE AND CHEERING
0:24:54 > 0:24:57Perhaps...can I offer you a drink afterwards?
0:24:57 > 0:24:59- Do you need a drop of water after that?- Yes, definitely.
0:24:59 > 0:25:01- Lots of water.- Would you want this?
0:25:01 > 0:25:03This is our Fountain of Youth.
0:25:03 > 0:25:05In fact, we've got a guinea pig trying this.
0:25:05 > 0:25:07Tim, how's it going?
0:25:07 > 0:25:09- How's your Fountain of Youth? - Just the same.
0:25:09 > 0:25:12- Don't feel any different at all. - No wrinkles gone yet?
0:25:12 > 0:25:15- No, still there! - OK, we'll come back.
0:25:15 > 0:25:18We'll give it a chance later. But, anyway, thank you very much.
0:25:18 > 0:25:20I'll give that one to you. Thank you for coming.
0:25:20 > 0:25:21Thank you. Cheers.
0:25:21 > 0:25:24APPLAUSE AND CHEERING
0:25:28 > 0:25:31So, we've seen, then, that we need to put energy in
0:25:31 > 0:25:32to split up our water.
0:25:32 > 0:25:34And a lot of energy is needed there,
0:25:34 > 0:25:37and I don't think that using Olympic cyclists...
0:25:37 > 0:25:41Even Britain doesn't have enough Olympic gold medal cyclists
0:25:41 > 0:25:44to power all the vehicles in the future using hydrogen.
0:25:44 > 0:25:46But there is another way of doing this.
0:25:46 > 0:25:51Our plants here use the energy from sunlight to split up water.
0:25:51 > 0:25:53They spit out oxygen during the daytime, of course,
0:25:53 > 0:25:55but they're using the hydrogen
0:25:55 > 0:25:57to build up the molecules they're made from.
0:25:57 > 0:25:59So maybe we can learn from nature.
0:25:59 > 0:26:05Now, Professor Akihiko Kudo from the Tokyo University of Science
0:26:05 > 0:26:08has worked on a catalyst here.
0:26:08 > 0:26:11This is really quite remarkable stuff. This is quite cutting edge.
0:26:11 > 0:26:13This is a catalyst that can use
0:26:13 > 0:26:17the energy of light to split up water.
0:26:17 > 0:26:19And the catalyst is made of...
0:26:19 > 0:26:22Well, actually, if we can just have our periodic tables up for a moment.
0:26:22 > 0:26:24Very good, periodic tables!
0:26:24 > 0:26:27OK, this catalyst is made up of the element sodium.
0:26:27 > 0:26:29Sodium, give us a little wave!
0:26:29 > 0:26:31There we are. Very good, sodium.
0:26:31 > 0:26:32OK, can you see sodium there?
0:26:32 > 0:26:36And we've got tantalum, right in the centre. Very good, tantalum.
0:26:36 > 0:26:39And oxygen up there. So this is sodium tantalate,
0:26:39 > 0:26:42and it's doped with lanthanum. Where's lanthanum?
0:26:42 > 0:26:43There's lanthanum. Very good.
0:26:43 > 0:26:45Give us a little wave at the top there.
0:26:45 > 0:26:48So this is the catalyst that he's developed,
0:26:48 > 0:26:51and this will convert the energy from light
0:26:51 > 0:26:53and use this energy to split up water.
0:26:53 > 0:26:55So, at ease, periodic tables!
0:26:55 > 0:26:57Back down, thank you very much.
0:26:57 > 0:26:59- OK, so are we ready?- Yep.
0:26:59 > 0:27:03OK, now, we're just going to put this on, then.
0:27:04 > 0:27:07OK, now, so this is the catalyst,
0:27:07 > 0:27:10sodium tantalate doped with lanthanum,
0:27:10 > 0:27:14and we're shining UV light on this,
0:27:14 > 0:27:17and, yes, I can see some bubbles.
0:27:17 > 0:27:21There are some bubbles in the upper part of the chamber there.
0:27:21 > 0:27:23If we just move up, we can see some. There we are.
0:27:23 > 0:27:27This is bubbles forming. So, as I say, this is quite remarkable.
0:27:27 > 0:27:32This is using light energy to catalytically split up,
0:27:32 > 0:27:34so this is not changing the catalyst,
0:27:34 > 0:27:39but it's splitting up water into hydrogen gas and oxygen gas.
0:27:39 > 0:27:41So we can see these bubbles here.
0:27:41 > 0:27:44Now, unfortunately, the slight snag with this one
0:27:44 > 0:27:48is that it's using ultraviolet light and not just visible light.
0:27:48 > 0:27:50The plants, of course, use visible light.
0:27:50 > 0:27:52But scientists all round the world
0:27:52 > 0:27:55are trying to work on developing a catalyst
0:27:55 > 0:27:58that will work very efficiently with visible light instead.
0:27:58 > 0:28:00And if you can do that...
0:28:00 > 0:28:02Well, maybe somebody from the audience
0:28:02 > 0:28:05will be the scientist that actually finds a catalyst
0:28:05 > 0:28:06that will work with visible light.
0:28:06 > 0:28:09And if you can do that, you're going to be very rich,
0:28:09 > 0:28:13and you will help to solve the world's energy problems.
0:28:13 > 0:28:18Right, so, I think it's time that we actually checked the water,
0:28:18 > 0:28:20after all this time making it.
0:28:20 > 0:28:22So we had to take a lot of precautions here,
0:28:22 > 0:28:24to ensure that this really is extra pure.
0:28:24 > 0:28:27This is something you should NEVER normally do
0:28:27 > 0:28:28during any science experiment.
0:28:28 > 0:28:31You shouldn't drink the products of the reaction.
0:28:31 > 0:28:33But this apparatus has been specially designed for this.
0:28:33 > 0:28:36We've used extra pure oxygen, medical oxygen,
0:28:36 > 0:28:38we've used extra pure hydrogen here.
0:28:38 > 0:28:42So I am actually going to just try a few drops of this.
0:28:47 > 0:28:49Actually, it doesn't taste too nice, to be honest!
0:28:49 > 0:28:51LAUGHTER
0:28:51 > 0:28:53But it's basically just pure water.
0:28:53 > 0:28:56And Tim was using the Fountain of Youth water.
0:28:56 > 0:28:59If we look on the bottle of the Fountain of Youth water,
0:28:59 > 0:29:01we see there are other minerals dissolved in it.
0:29:01 > 0:29:04This is, of course, because water is a very good solvent -
0:29:04 > 0:29:05things dissolve in it -
0:29:05 > 0:29:08and, well, look at all the other components in our water.
0:29:08 > 0:29:11We've got, for instance, there's a lot of calcium,
0:29:11 > 0:29:13there's quite a lot of calcium there.
0:29:13 > 0:29:16There's quite a bit of sodium in this, as well.
0:29:16 > 0:29:17So, sodium, what's your symbol?
0:29:17 > 0:29:19- SODIUM:- Na!
0:29:19 > 0:29:23- OK, and do you have- Na- idea where this comes from?
0:29:23 > 0:29:25Where does this symbol come from?
0:29:25 > 0:29:26Any ideas? No? No? OK.
0:29:26 > 0:29:28Well, I'm going to show you.
0:29:28 > 0:29:31Hold the sign up, please, so we can all see. That's it.
0:29:31 > 0:29:32So, Na, where does this come from?
0:29:32 > 0:29:34Well, actually, I have a book here.
0:29:34 > 0:29:36Thank you. Now, in the book,
0:29:36 > 0:29:40we can see that this is a chap...
0:29:40 > 0:29:43This book is from 1557,
0:29:43 > 0:29:46and this man here, he's making piles of compound here,
0:29:46 > 0:29:49and this is actually sodium carbonate.
0:29:49 > 0:29:51They called it natron or niter. And this is...
0:29:51 > 0:29:55He's taking Nile water here, so this is water from the Nile,
0:29:55 > 0:29:58and this is why it's called niter, from the Nile water.
0:29:58 > 0:30:00This corrupted into natron,
0:30:00 > 0:30:03and this is the word that gives us the symbol for sodium.
0:30:03 > 0:30:06Na comes from the Latin version of this, natrium.
0:30:06 > 0:30:08But it was first discovered in water.
0:30:08 > 0:30:11OK, thank you. So, periodic table, at ease.
0:30:11 > 0:30:14Thank you. Now, how was this detected?
0:30:14 > 0:30:18Because we can't see any of these substances in water,
0:30:18 > 0:30:21because they're present in such small quantities,
0:30:21 > 0:30:24we have to use a chemist's technique called spectroscopy.
0:30:24 > 0:30:28And this looks at how energy interacts with electrons in atoms.
0:30:28 > 0:30:31Give them some energy, they move up, and as they drop back down again,
0:30:31 > 0:30:33they can give out this energy as light.
0:30:33 > 0:30:38And each element has its own unique, characteristic, unique colours.
0:30:38 > 0:30:43It has its own spectrum, like a rainbow barcode for each element.
0:30:43 > 0:30:46And we're going to show this now with all these symbols here.
0:30:46 > 0:30:48These are the symbols from group 1 elements.
0:30:48 > 0:30:51Can we have group 1 only, please? That's it. Put them up.
0:30:51 > 0:30:54Hydrogen, well, you are, of course, a component of water.
0:30:54 > 0:30:57You're not really IN water, dissolved in it,
0:30:57 > 0:30:58so you can put your card down.
0:30:58 > 0:31:01Francium, I'm afraid you're too radioactive,
0:31:01 > 0:31:03so there's going to be no francium in our water,
0:31:03 > 0:31:05so you can put your card down, as well.
0:31:05 > 0:31:08But these other group 1 elements, well, here they are here.
0:31:08 > 0:31:11We've actually taken some symbols here
0:31:11 > 0:31:13and soaked each of these symbols with salts.
0:31:13 > 0:31:16With compounds of the appropriate elements.
0:31:16 > 0:31:18And watch what happens when we light them.
0:31:36 > 0:31:40APPLAUSE
0:31:47 > 0:31:50We can certainly see that the sodium and lithium are very different,
0:31:50 > 0:31:52but these ones look rather similar.
0:31:52 > 0:31:53But, actually, they're not.
0:31:53 > 0:31:55If we were to look very closely
0:31:55 > 0:31:57at the colours of light coming down here,
0:31:57 > 0:32:00if we split them up using a spectroscope,
0:32:00 > 0:32:02we would see they have slightly different colours.
0:32:02 > 0:32:05The exact frequencies of light coming out
0:32:05 > 0:32:07are unique to these elements.
0:32:07 > 0:32:09Now these two elements, caesium and rubidium,
0:32:09 > 0:32:13were also first discovered in water.
0:32:13 > 0:32:16And they were discovered by Robert Bunsen.
0:32:16 > 0:32:20This is Bunsen of Bunsen burner fame, of course -
0:32:20 > 0:32:21not to be confused with
0:32:21 > 0:32:24Bunsen Honeydew from the Muppets, shown here!
0:32:24 > 0:32:26LAUGHTER
0:32:26 > 0:32:31But Robert Bunsen took litres of mineral water, evaporated this,
0:32:31 > 0:32:35and he found these new elements in the water using spectroscopy.
0:32:35 > 0:32:37And, in fact, he named these elements
0:32:37 > 0:32:40from the appearance of their spectra -
0:32:40 > 0:32:42caesium from the sky blue lines in its spectra,
0:32:42 > 0:32:47and rubidium from two very distinct red lines in its spectrum.
0:32:47 > 0:32:50OK, so, how do we find these elements, though?
0:32:50 > 0:32:53They appear in compounds in water, not as their elements.
0:32:53 > 0:32:56All of you, all you group 1 elements,
0:32:56 > 0:32:58you're actually metals.
0:32:58 > 0:33:00We certainly don't find metals in water.
0:33:00 > 0:33:04And that's because all of these metals actually react with water.
0:33:04 > 0:33:06And this is what we're going to show you now.
0:33:06 > 0:33:08So we have here a tank,
0:33:08 > 0:33:12and I'm going to add a tiny little piece of sodium to the tank.
0:33:12 > 0:33:14Let's have this one. A little piece of sodium.
0:33:14 > 0:33:17A little tiny piece. I'm going to drop it into the water.
0:33:17 > 0:33:19There it is, dancing around the surface.
0:33:19 > 0:33:22So it's lighter than water, floating on the top,
0:33:22 > 0:33:24but it's actually reacting with the water.
0:33:24 > 0:33:26We can see it's reacted there.
0:33:26 > 0:33:28It's giving out hydrogen gas.
0:33:28 > 0:33:31The sodium is giving up its electron to the water,
0:33:31 > 0:33:34to the hydrogen in the water, forming hydrogen gas, OK?
0:33:34 > 0:33:37It's rather disappointing to see that one, though.
0:33:37 > 0:33:38There's not a lot there.
0:33:38 > 0:33:44I think we need, actually, a bigger tank, and a bigger piece of sodium.
0:33:44 > 0:33:45So let's try this.
0:33:47 > 0:33:50OK, this is certainly a bigger piece of sodium.
0:33:50 > 0:33:53Now, of course, when this reaction is done at school,
0:33:53 > 0:33:55the teacher is always instructed
0:33:55 > 0:33:58to not use a piece larger than the size of a pea.
0:33:58 > 0:34:00And, well, I thought I'd show you why.
0:34:00 > 0:34:04So we've got a piece that IS a bit larger than the size of a pea.
0:34:04 > 0:34:08Now then, we're going to add this piece of sodium, then, to the water.
0:34:08 > 0:34:10Are you ready? And, step back.
0:34:12 > 0:34:14So it's floating on the surface there...
0:34:14 > 0:34:17EXPLOSION AUDIENCE GASPS
0:34:17 > 0:34:20- HE LAUGHS - There's certainly quite a lot of smoke!
0:34:20 > 0:34:24APPLAUSE AND CHEERING
0:34:32 > 0:34:34Well, you can certainly see why
0:34:34 > 0:34:37you shouldn't add a piece larger than the size of a pea!
0:34:37 > 0:34:40LAUGHTER COUGHING
0:34:40 > 0:34:43Oh, dear! I've poisoned the audience!
0:34:43 > 0:34:46- It's chemistry! - COUGHING
0:34:46 > 0:34:47Right, now...
0:34:47 > 0:34:52But it's not just water that sodium can give its electron to.
0:34:52 > 0:34:59We can also... It can give its electron to oxygen.
0:34:59 > 0:35:00So here is a piece of sodium
0:35:00 > 0:35:03and I'm just going to cut this now
0:35:03 > 0:35:06and chop it right down the middle.
0:35:06 > 0:35:08There we are.
0:35:09 > 0:35:11So this is beautiful, silvery metal.
0:35:11 > 0:35:14So this is what sodium normally looks like.
0:35:14 > 0:35:17But just as it's left here, exposed to the air,
0:35:17 > 0:35:20it's reacting with the oxygen in the air.
0:35:20 > 0:35:23It's actually giving up its electron to oxygen.
0:35:23 > 0:35:25OK, we can see it's changing.
0:35:25 > 0:35:28It's actually got a sort of white crust
0:35:28 > 0:35:29developing over the surface.
0:35:29 > 0:35:31But, actually, if we just have
0:35:31 > 0:35:33our periodic table up for the moment,
0:35:33 > 0:35:36and I want to focus on group 1 again.
0:35:36 > 0:35:38So others, down. Just group 1 up.
0:35:38 > 0:35:40So we have sodium here,
0:35:40 > 0:35:43and the key thing here is this outermost electron sodium has.
0:35:43 > 0:35:45I think we have a graphic to show this.
0:35:45 > 0:35:47This is the atomic structure of sodium.
0:35:47 > 0:35:49We have one outermost electron there.
0:35:49 > 0:35:53This is the thing that's very easily given in chemical reactions.
0:35:53 > 0:35:54But as we come down the group,
0:35:54 > 0:35:57you've all got this one outermost electron,
0:35:57 > 0:35:59but if we look at, say, caesium, right at the bottom,
0:35:59 > 0:36:02so here's caesium, and has lots more electrons,
0:36:02 > 0:36:05but, again, there's one outermost electron,
0:36:05 > 0:36:08and this is even more easily lost than it is for sodium.
0:36:08 > 0:36:11And, well, we have some here.
0:36:11 > 0:36:14This is caesium in this vessel.
0:36:14 > 0:36:17The problem was, we need to store it under argon,
0:36:17 > 0:36:19and we had a slight problem.
0:36:19 > 0:36:22We sealed it up so well, we can't get it out!
0:36:22 > 0:36:24LAUGHTER
0:36:24 > 0:36:26So, I think the simplest thing to do
0:36:26 > 0:36:29is actually to hit it with a hammer,
0:36:29 > 0:36:31which is what I'm going to do.
0:36:31 > 0:36:33- HAMMERING - Oh, well, that did it!
0:36:33 > 0:36:35This is such a reactive element
0:36:35 > 0:36:38that is soon as it comes into contact with the air...
0:36:38 > 0:36:40in fact, if you have the lights down,
0:36:40 > 0:36:43you might be able to see some of the sparks that are...
0:36:43 > 0:36:45ooh, yes, look at this.
0:36:45 > 0:36:47This is SO reactive that as soon as...
0:36:47 > 0:36:48Ooh, dear! Lots of sparks!
0:36:48 > 0:36:52..as soon as it as it comes into contact with the air, it's gone off.
0:36:52 > 0:36:55It WAS a nice, shiny metal. It was a sort of silvery colour.
0:36:55 > 0:36:57Sometimes it has a slight golden colour,
0:36:57 > 0:37:00but when comes into contact with air, it forms this black oxide.
0:37:00 > 0:37:03So, the caesium is incredibly reactive
0:37:03 > 0:37:06and it's given its electron to the oxygen.
0:37:06 > 0:37:10But there are other things that can take the electron away
0:37:10 > 0:37:12from these group 1 elements,
0:37:12 > 0:37:15and one of them is contained in this, in bleach.
0:37:15 > 0:37:17Does anyone know what element is in this?
0:37:17 > 0:37:19AUDIENCE MEMBER: Chlorine!
0:37:19 > 0:37:21Chlorine! Where's chlorine?
0:37:21 > 0:37:24Yes, you're in bleach. This gives the bleach its colour.
0:37:24 > 0:37:27You're a really poisonous, nasty element, I'm afraid.
0:37:27 > 0:37:30You were used in World War I as a toxic gas.
0:37:30 > 0:37:32Not very nice!
0:37:32 > 0:37:36But you're very efficient, though, at taking electrons from things.
0:37:36 > 0:37:38OK, we're going to see some chlorine in just a moment,
0:37:38 > 0:37:41but before I show you that, I want to show you something else.
0:37:41 > 0:37:44This is a really, really remarkable book.
0:37:44 > 0:37:48This is from the archives in the Royal Institution here.
0:37:48 > 0:37:51And this was from a lecture
0:37:51 > 0:37:54that was delivered exactly 200 years ago, in 1812.
0:37:54 > 0:37:56And the lectures were four lectures,
0:37:56 > 0:38:00being part of a course on the elements of chemical philosophy,
0:38:00 > 0:38:04delivered by Sir Humphrey Davy exactly 200 years ago.
0:38:04 > 0:38:07Sir Humphrey Davy was the first person to isolate,
0:38:07 > 0:38:10among other elements, sodium and potassium,
0:38:10 > 0:38:12and he also named chlorine over there.
0:38:12 > 0:38:15And these lectures were written down during the lecture course
0:38:15 > 0:38:17by a young Michael Faraday,
0:38:17 > 0:38:21who was sitting in the audience, exactly where you are now.
0:38:21 > 0:38:23Davy was so impressed with these notes
0:38:23 > 0:38:26that Faraday wrote up of the lectures,
0:38:26 > 0:38:27that he gave him a job.
0:38:27 > 0:38:29He got a job here at the Royal Institution
0:38:29 > 0:38:33and became one of the world's most famous scientists ever.
0:38:33 > 0:38:35Now, I'm certainly no Humphrey Davy,
0:38:35 > 0:38:37but who knows, sitting in this audience
0:38:37 > 0:38:40there may well be the next Michael Faraday.
0:38:40 > 0:38:43Now, this is what I wanted to show you, though.
0:38:43 > 0:38:46In this book, Experiments Belonging To The Lecture On Chlorine,
0:38:46 > 0:38:51it says, "Mr Davy exhibited a specimen of chlorine gas.
0:38:51 > 0:38:53"It was in a clean glass tube."
0:38:53 > 0:38:59OK, now, we actually have that original sample of chlorine gas.
0:38:59 > 0:39:04Here it is. This is the one that Davy exhibited back in 1812,
0:39:04 > 0:39:06which is quite remarkable.
0:39:06 > 0:39:09So chlorine gets its name, Davy gave it its name,
0:39:09 > 0:39:12from the Greek, "chloros" meaning "green",
0:39:12 > 0:39:14because of this greeny colour that it has.
0:39:14 > 0:39:18We even have a sample of the original sodium,
0:39:18 > 0:39:21and this is Davy's original sodium,
0:39:21 > 0:39:24prepared here at the Royal Institution.
0:39:24 > 0:39:27This is the metal, floating, protected in oil,
0:39:27 > 0:39:31because, as we've seen, it goes off in air very quickly.
0:39:31 > 0:39:34So, we've got sodium and we've got chlorine.
0:39:34 > 0:39:36Well, what happens when you mix the two?
0:39:36 > 0:39:38Well, you get some sodium chloride.
0:39:38 > 0:39:41Now, they would kill me if I did this, of course, with these,
0:39:41 > 0:39:45so I'm not going to use the original samples of sodium and chlorine.
0:39:45 > 0:39:48But we do have some other samples here.
0:39:48 > 0:39:51Here's our sodium, here's our chlorine.
0:39:51 > 0:39:55And you can see this beautiful green colour now of the chlorine,
0:39:55 > 0:39:58you can see the beautiful silvery colour of the sodium.
0:39:58 > 0:40:00We've taken all the air out of this side,
0:40:00 > 0:40:04because we know that sodium reacts very violently with air,
0:40:04 > 0:40:05so there's no air here.
0:40:05 > 0:40:09I'm just going to pop my goggles on, if I can do that one-handedly.
0:40:09 > 0:40:13There we go. And I'm now going to let the chlorine from this side
0:40:13 > 0:40:15into this side, and see what happens.
0:40:15 > 0:40:17So let's have a look.
0:40:17 > 0:40:20Look at that. This is sodium meets chlorine,
0:40:20 > 0:40:23and the silver mirror has disappeared,
0:40:23 > 0:40:27and we've got this white crust forming all the way round here.
0:40:27 > 0:40:31It's gone white, looks like salt, and, well,
0:40:31 > 0:40:33that's because what we've made here is salt -
0:40:33 > 0:40:35it's sodium chloride.
0:40:35 > 0:40:38So the chlorine reacts with the sodium,
0:40:38 > 0:40:41the chlorine takes the electron from the sodium,
0:40:41 > 0:40:43to form white sodium chloride.
0:40:43 > 0:40:46This is just the sort of thing you would put on your chips.
0:40:46 > 0:40:47The chlorine itself is poisonous.
0:40:47 > 0:40:51It reacts by taking electrons from your body and poisons you.
0:40:51 > 0:40:53The sodium is poisonous. It gives its electron to you.
0:40:53 > 0:40:55But once they've reacted,
0:40:55 > 0:40:58we've got sodium chloride and you eat it.
0:40:58 > 0:41:00OK, thank you very much.
0:41:00 > 0:41:03APPLAUSE
0:41:09 > 0:41:11But there are actually different sorts of salt.
0:41:11 > 0:41:14Sodium chloride is just one salt. There are others.
0:41:14 > 0:41:17And if we have our halogens up for a moment...
0:41:17 > 0:41:20OK, all of you are very good at forming salts,
0:41:20 > 0:41:23especially with group 1. Can we have group 1 up, as well, please?
0:41:23 > 0:41:25OK, any mixtures of you would form salts.
0:41:25 > 0:41:27Not only could we have sodium chloride,
0:41:27 > 0:41:31we could have potassium bromide, potassium chloride, or so on.
0:41:31 > 0:41:33In fact, all of you halogens...
0:41:33 > 0:41:37Do you know what the name "halogen" actually means? Does anyone know?
0:41:37 > 0:41:39Does anyone know anywhere?
0:41:39 > 0:41:42It means "salt-former".
0:41:42 > 0:41:45So you're all really good forming salts.
0:41:45 > 0:41:48In fact, that's how, as a group, you get your name.
0:41:48 > 0:41:50So salts, though, have very different properties
0:41:50 > 0:41:52when they're dissolved in the water.
0:41:52 > 0:41:55The water itself is completely different.
0:41:55 > 0:41:57Seawater is not the same as normal water,
0:41:57 > 0:42:00and, well, we have some seawater here to show you.
0:42:00 > 0:42:03Thank you very much, periodic tables. If you go down for a moment.
0:42:03 > 0:42:06So I was fortunate enough to visit the Dead Sea.
0:42:06 > 0:42:09In fact, this is me floating in the Dead Sea up here.
0:42:09 > 0:42:11- LAUGHTER - So while I was floating,
0:42:11 > 0:42:14I was thinking, "Well, what would it be like?
0:42:14 > 0:42:18"What sort of things could we get to float on the Dead Sea?"
0:42:18 > 0:42:21Well, I need a volunteer, actually, to help out with this.
0:42:21 > 0:42:23And we'll have somebody from...
0:42:23 > 0:42:26Yes, yes. If you'd like to come down. Lovely.
0:42:26 > 0:42:28- APPLAUSE - Thank you very much.
0:42:28 > 0:42:30If you'd like to face the front here.
0:42:30 > 0:42:32- What's your name, please?- Katie.
0:42:32 > 0:42:35Right, good. We need to put some protective clothing when you,
0:42:35 > 0:42:38so just come over here and put on some protective clothing.
0:42:38 > 0:42:41I've got a block of metal here.
0:42:41 > 0:42:43Now, what do you think to this block of metal?
0:42:43 > 0:42:46If you just hold this. What do you think?
0:42:46 > 0:42:49- It's really heavy. - It's really heavy, yes?
0:42:49 > 0:42:52OK, really heavy. What do you think? How heavy?
0:42:52 > 0:42:53Quite heavy, yeah.
0:42:53 > 0:42:55So this IS solid metal. This is actually...
0:42:55 > 0:42:58You're looking very good in those! Very fetching!
0:42:58 > 0:43:00We've got a step here, which was a very good thing!
0:43:00 > 0:43:02If you'd like to stand on this step.
0:43:02 > 0:43:06OK, this is some salty water. This is essentially seawater.
0:43:06 > 0:43:08I'm going to put on my gloves, as well.
0:43:08 > 0:43:11You haven't held this yet. If you just hold that.
0:43:11 > 0:43:12Just stand there for a moment.
0:43:12 > 0:43:15Right, what you think of that? Quite heavy?
0:43:15 > 0:43:17Yeah! Quite heavy, actually!
0:43:17 > 0:43:18Yes, it is quite heavy.
0:43:18 > 0:43:21Right, do you think it's going to float in the Dead Sea,
0:43:21 > 0:43:23or sink in the Dead Sea?
0:43:25 > 0:43:26What you think? 50-50.
0:43:26 > 0:43:29- Float or sink? Ask the audience? - Float.
0:43:29 > 0:43:32- Ah, float, OK. Float in the Dead Sea.- Maybe. It's quite heavy.
0:43:32 > 0:43:33Covering your bets there.
0:43:33 > 0:43:35OK, it is quite heavy, though, isn't it?
0:43:35 > 0:43:37Let's see, shall we? We're going to drop it in.
0:43:37 > 0:43:39You take that side. That's it.
0:43:39 > 0:43:41And you put that in the water.
0:43:41 > 0:43:44Lower it in gently, you don't want to splash it everywhere.
0:43:44 > 0:43:47That's it. OK, very good. And just let go.
0:43:47 > 0:43:49- And...- Oh, no!
0:43:49 > 0:43:50Aw! Well, it sinks.
0:43:50 > 0:43:53It did sink, yes! It sank pretty quickly.
0:43:53 > 0:43:55It was quite heavy, wasn't it?
0:43:55 > 0:43:57It did sink pretty quickly there.
0:43:57 > 0:43:59I'll see if I can fish it out for you.
0:43:59 > 0:44:01I'll do this, I've got longer gloves.
0:44:01 > 0:44:03- And...ooh, not that long! - LAUGHTER
0:44:03 > 0:44:07Anyway, right, out comes the magnesium here.
0:44:07 > 0:44:08This is a block of pure magnesium.
0:44:08 > 0:44:11It is actually quite heavy, you're right!
0:44:11 > 0:44:14OK, there we are. Now, we've got some other water here.
0:44:14 > 0:44:16So this one contains sodium salts,
0:44:16 > 0:44:18but this one contains caesium salts.
0:44:18 > 0:44:21And if we just have our group 1 up again for a moment.
0:44:21 > 0:44:22Oh, very good! Very efficient!
0:44:22 > 0:44:24Sodium right at the top there,
0:44:24 > 0:44:26and as we go down, we get to caesium.
0:44:26 > 0:44:29And, so, caesium is actually heavier than sodium.
0:44:29 > 0:44:33And, now, how quickly do you think this is going to sink in this one?
0:44:33 > 0:44:35- Er, maybe a bit longer. - Take a bit longer to sink?
0:44:35 > 0:44:38Yep, OK, all right. So shall we try this one?
0:44:38 > 0:44:40I'm just going to put this in the water.
0:44:40 > 0:44:42Are you ready? Do you want to hold it there, as well?
0:44:42 > 0:44:44Just gently let go. And, ready?
0:44:44 > 0:44:46After three. 1, 2, 3, go!
0:44:48 > 0:44:50AUDIENCE GASPS
0:44:50 > 0:44:52Ooh!
0:44:52 > 0:44:55LAUGHTER
0:44:55 > 0:44:58- Watch out for your gloves! - LAUGHTER
0:44:58 > 0:45:00No, so it's not actually going to sink.
0:45:00 > 0:45:03It actually floats in the water. So I'll just fish that out,
0:45:03 > 0:45:06and I think you should get a big round of applause
0:45:06 > 0:45:08- for your help there. - APPLAUSE
0:45:08 > 0:45:09Thank you.
0:45:09 > 0:45:12We'll just take those off you. That's it. Lovely stuff.
0:45:12 > 0:45:14Thank you very much indeed.
0:45:14 > 0:45:17Yes, the block of metal actually floats in the caesium salts,
0:45:17 > 0:45:22and that's because caesium itself is a heavier atom than sodium is.
0:45:22 > 0:45:26We can get other salts, though, from the Dead Sea, for instance.
0:45:26 > 0:45:29It's not just sodium chloride. In fact, in the Dead Sea
0:45:29 > 0:45:31it's quite rich in another salt.
0:45:31 > 0:45:33If we have our halogens back, please.
0:45:33 > 0:45:36OK, we have bromine in the Dead Sea, as well.
0:45:36 > 0:45:39It's not as bromine itself, not as the element. It's as bromide.
0:45:39 > 0:45:41This is where it's taken an electron from something
0:45:41 > 0:45:43and formed a negative bromide ion.
0:45:43 > 0:45:46So we'd get things like potassium bromide, sodium bromide,
0:45:46 > 0:45:48if we evaporated our Dead Sea water.
0:45:48 > 0:45:51And, actually, I can demonstrate this
0:45:51 > 0:45:53with some of the Dead Sea water.
0:45:53 > 0:45:56I've got some concentrated Dead Sea water.
0:45:56 > 0:45:58I brought this back from the Dead Sea.
0:45:58 > 0:46:00Just the sort of thing you normally bring back, I suppose,
0:46:00 > 0:46:02if you're a chemist!
0:46:02 > 0:46:04Right, here we are. Here's my Dead Sea water.
0:46:04 > 0:46:08And I'm just going to add some bleach to that.
0:46:08 > 0:46:11Of course, the bleach has chlorine atoms in it.
0:46:11 > 0:46:13Watch what happens, just give it a bit of a...
0:46:13 > 0:46:16AUDIENCE GASPS
0:46:16 > 0:46:19OK. This, the colour that you now see...
0:46:19 > 0:46:20And we haven't cheated in any way,
0:46:20 > 0:46:23this really is just Dead Sea water that I brought back.
0:46:23 > 0:46:26We just concentrated it a bit by removing some water.
0:46:26 > 0:46:27This is just bleach.
0:46:27 > 0:46:30The colour that you see now is bromine.
0:46:30 > 0:46:33So with our halogens, we've got bromide here,
0:46:33 > 0:46:36and I've just added some chlorine that was in the bleach.
0:46:36 > 0:46:39So what we have there, the bromide reacts with the chlorine,
0:46:39 > 0:46:42chlorine takes the electron from bromide,
0:46:42 > 0:46:45and forums bromine element and leaves chloride ions.
0:46:45 > 0:46:48But chlorine, look behind you. Who's behind you?
0:46:48 > 0:46:50Fluorine!
0:46:50 > 0:46:51Fluorine, exactly!
0:46:51 > 0:46:55No fluorine is even better at taking electrons away,
0:46:55 > 0:46:58and fluorine can take the electron away from chloride.
0:46:58 > 0:46:59OK, fluorine, in fact...
0:46:59 > 0:47:01That's right, give us a little wave!
0:47:01 > 0:47:04Fluorine, you are THE most reactive non-metal
0:47:04 > 0:47:06in the entire periodic table.
0:47:06 > 0:47:09You will steal an electron from every other element
0:47:09 > 0:47:12in the entire periodic table, with the slight exception
0:47:12 > 0:47:14of the very inert noble gases sitting next to you.
0:47:14 > 0:47:17But everything else, you will react with. Very, very violent.
0:47:17 > 0:47:20Fluorine is probably THE most reactive element
0:47:20 > 0:47:22in the entire periodic table.
0:47:22 > 0:47:24Certainly the most reactive non-metal.
0:47:24 > 0:47:27Even as a chemist, I had never seen any fluorine,
0:47:27 > 0:47:30and I thought, for these lectures,
0:47:30 > 0:47:34it would be really nice to bring some fluorine into the lectures
0:47:34 > 0:47:36and I needed to find a specialist to do this.
0:47:36 > 0:47:40So, would you please welcome, from the University of Leicester,
0:47:40 > 0:47:42Professor Eric Hope, a fluorine chemist.
0:47:42 > 0:47:45APPLAUSE
0:47:46 > 0:47:48Eric, thank you for coming along.
0:47:48 > 0:47:50So, Eric is a fluorine specialist.
0:47:50 > 0:47:52Fluorine is incredibly reactive.
0:47:52 > 0:47:55- It reacts with just about everything, doesn't it?- Indeed.
0:47:55 > 0:47:58So, the question everyone wants to ask is, how do you store it?
0:47:58 > 0:48:01Doesn't it react with the container you put it in?
0:48:01 > 0:48:02It does react with the container.
0:48:02 > 0:48:05You can store it in metal containers, stainless steel,
0:48:05 > 0:48:08or we hold it in nickel containers in Leicester.
0:48:08 > 0:48:10And what happens is the fluorine reacts
0:48:10 > 0:48:11with a coating of the metal,
0:48:11 > 0:48:14you get nickel difluoride, a very few microns thick,
0:48:14 > 0:48:16protects the rest of the nickel metal,
0:48:16 > 0:48:18and you get an impervious layer.
0:48:18 > 0:48:22So it HAS reacted, and what it's formed is pretty inert afterwards.
0:48:22 > 0:48:23Indeed, yes.
0:48:23 > 0:48:26But fluorine is incredibly reactive and dangerous, isn't it?
0:48:26 > 0:48:29If you control and handle it under appropriate conditions,
0:48:29 > 0:48:32then it is dangerous, but it's not THAT dangerous.
0:48:32 > 0:48:35- It's very reactive, isn't it? - It'll react, as you said,
0:48:35 > 0:48:38with virtually every element in the periodic table.
0:48:38 > 0:48:42When I contacted Eric, I thought, fluorine, really reactive,
0:48:42 > 0:48:45it would be very great if we could bring some of this into the RI.
0:48:45 > 0:48:48But one reaction that I've always wanted to try
0:48:48 > 0:48:50is the reaction between fluorine -
0:48:50 > 0:48:53because, you know, it is one of THE most reactive non-metals -
0:48:53 > 0:48:56I thought I'd like to try the reaction of fluorine
0:48:56 > 0:48:59with THE most reactive metal in the periodic table, caesium.
0:48:59 > 0:49:01Yes, you are best electron-giver! Very generous!
0:49:01 > 0:49:04So this should be a really violent reaction.
0:49:04 > 0:49:06I thought, I'd love to see this!
0:49:06 > 0:49:08What did you think of this, when I said I wanted to try
0:49:08 > 0:49:11the reaction of fluorine with caesium?
0:49:11 > 0:49:14I thought it was the most outlandish thing I'd ever heard,
0:49:14 > 0:49:17and it took me a good 24 hours to think about whether or not
0:49:17 > 0:49:19it was feasible or possible to actually do.
0:49:19 > 0:49:22OK. Yes, exactly, we did wonder whether we could actually do this.
0:49:22 > 0:49:25Shall we just have the periodic table down?
0:49:25 > 0:49:27We thought, "How could we do this safely?"
0:49:27 > 0:49:28And we did have a practice
0:49:28 > 0:49:30just to make sure we could do this safely.
0:49:30 > 0:49:32In fact, the remarkable thing was,
0:49:32 > 0:49:36as I say, I'm a chemist, and I've never actually seen...
0:49:36 > 0:49:38I hadn't seen fluorine before, before I went up to Leicester,
0:49:38 > 0:49:41- and remarkably, well... - I've never seen caesium before!
0:49:41 > 0:49:43Eric had never seen caesium!
0:49:43 > 0:49:46So we thought we HAD to get together, really!
0:49:46 > 0:49:48So I thought I'd bring my caesium along to Leicester,
0:49:48 > 0:49:50and we did test things,
0:49:50 > 0:49:52and we're going to try and do this for you now.
0:49:52 > 0:49:55I'm actually just going to hold this in my hand.
0:49:55 > 0:49:59Just holding this in my hand actually just melts the caesium.
0:49:59 > 0:50:03So the bond between the caesium atoms here are so weak,
0:50:03 > 0:50:05just holding it in my hand melts this. There we are.
0:50:05 > 0:50:09We've certainly got some caesium at the bottom of this tube.
0:50:10 > 0:50:12Right, we're going to try, then,
0:50:12 > 0:50:15the reaction between caesium and fluorine.
0:50:15 > 0:50:21The caesium is protected by this blanket of argon...
0:50:23 > 0:50:26..which is heavier than air.
0:50:26 > 0:50:29And we've seen that caesium reacts with the air.
0:50:32 > 0:50:35And I'm just going to lower this on...
0:50:40 > 0:50:43..like so, and push this down.
0:50:46 > 0:50:48OK, and I think we're ready to try, then.
0:50:50 > 0:50:51Ah!
0:50:51 > 0:50:54AUDIENCE GASPS APPLAUSE
0:51:08 > 0:51:10OK, so it's an incredibly violent reaction.
0:51:10 > 0:51:12We're using tiny quantities.
0:51:12 > 0:51:15Well, we used more caesium here, but a tiny quantity of fluorine.
0:51:15 > 0:51:18We have to just use a tiny, tiny bit. It's in this tube here.
0:51:18 > 0:51:22But it did react very, very violently with the caesium,
0:51:22 > 0:51:23to form caesium fluoride.
0:51:23 > 0:51:26OK, well, I think we need to give a big round of applause
0:51:26 > 0:51:28to Professor Eric Hope.
0:51:28 > 0:51:30APPLAUSE
0:51:33 > 0:51:36So, once the caesium has reacted with the fluorine,
0:51:36 > 0:51:39again, the caesium gives up its electron,
0:51:39 > 0:51:43and it's no longer the reactive caesium metal that we started with.
0:51:43 > 0:51:45And, of course, the fluorine, once it grabs the electron,
0:51:45 > 0:51:48it's no longer the reactive fluorine we started with.
0:51:48 > 0:51:50We've got fluoride ion.
0:51:50 > 0:51:53And actually, remarkably, fluoride is something that, again,
0:51:53 > 0:51:56you can find in every glass of drinking water you have.
0:51:56 > 0:51:59This is actually added to our tap water
0:51:59 > 0:52:02because it protects our teeth and prevents decay.
0:52:02 > 0:52:04Now, talking of preventing decay,
0:52:04 > 0:52:08I think we need to see how our Fountain of Youth volunteer got on,
0:52:08 > 0:52:11and see how whether it really has worked after all.
0:52:11 > 0:52:14So, Tim, how's it doing?
0:52:14 > 0:52:17- Has it worked? - I feel a lot younger!
0:52:17 > 0:52:19Tim, is that really you?!
0:52:20 > 0:52:23Ah, I can see what they did there!
0:52:23 > 0:52:26LAUGHTER AND APPLAUSE
0:52:30 > 0:52:32Tim, do you feel any different at all?
0:52:32 > 0:52:35No different at all, I'm afraid. Just the same age.
0:52:35 > 0:52:38OK, so it really looks like our Fountain of Youth water
0:52:38 > 0:52:41perhaps isn't restoring Tim's youth to him.
0:52:41 > 0:52:45But, nonetheless, water does play a very important role in our lives.
0:52:45 > 0:52:47Without it, we'd all be dead.
0:52:47 > 0:52:50And this is because water actually enables
0:52:50 > 0:52:52chemical reactions to take place,
0:52:52 > 0:52:55both inside the cells in your body and in other reactions.
0:52:55 > 0:53:00And this is what we're going to demonstrate now. I have...
0:53:00 > 0:53:05We've placed some magnesium powder and some silver nitrate.
0:53:05 > 0:53:08Now, they are touching each other at the moment.
0:53:08 > 0:53:11They're mixed up very intimately, but not quite intimately enough.
0:53:11 > 0:53:14What they need is to get into really close contact,
0:53:14 > 0:53:16and we do that by adding a drop of water.
0:53:16 > 0:53:21OK, now, they've given me a glass of water and a pipette,
0:53:21 > 0:53:25but I think I'm going to need the slightly longer pipette, please.
0:53:25 > 0:53:26This is quite a violent...
0:53:26 > 0:53:29Thank you, that's a better one. Right, now...
0:53:30 > 0:53:33I'm going to take the lid off of this.
0:53:33 > 0:53:35It's sitting here quite happily the moment,
0:53:35 > 0:53:37nothing is taking place,
0:53:37 > 0:53:40until we add a drop of water.
0:53:40 > 0:53:43OK, I'm adding it now.
0:53:44 > 0:53:47AUDIENCE GASPS
0:53:47 > 0:53:50APPLAUSE
0:53:57 > 0:54:01So this is an incredibly violent reaction that takes place,
0:54:01 > 0:54:05but it didn't take place until we added the water.
0:54:05 > 0:54:08So, maybe this gives us a method for slowing reactions down,
0:54:08 > 0:54:10if we remove the water.
0:54:10 > 0:54:13Well, I think, actually, it's getting time for my dinner,
0:54:13 > 0:54:17and they've brought on some bananas!
0:54:17 > 0:54:20Great! And these bananas have seen better days.
0:54:20 > 0:54:25Now, these bananas, I know, are two weeks old, actually.
0:54:25 > 0:54:27They've been sort of...eurgh!
0:54:29 > 0:54:30AUDIENCE GROANS
0:54:30 > 0:54:33It's actually a banana...
0:54:33 > 0:54:35AUDIENCE GROANS LOUDLY
0:54:37 > 0:54:40It's seen better days, I think.
0:54:40 > 0:54:42But this banana...
0:54:42 > 0:54:45..this banana, this one was two weeks old.
0:54:45 > 0:54:49This banana here is actually six YEARS old.
0:54:49 > 0:54:52- AUDIENCE GROANS - Yeah, if I was going to eat one,
0:54:52 > 0:54:54I know which one I'd rather have!
0:54:54 > 0:54:56Now, why has this one lasted so long?
0:54:56 > 0:54:58Actually, what do you think? Have a look at this.
0:54:58 > 0:55:01What do you think? What does it feel like?
0:55:01 > 0:55:02- Scaly.- Scaly? Uh-huh.
0:55:02 > 0:55:05What do you think? What do you think it feels like?
0:55:05 > 0:55:08- Quite hard.- Quite hard, yes.
0:55:08 > 0:55:09It IS quite hard.
0:55:09 > 0:55:13And this is because we've removed all the water from this banana.
0:55:13 > 0:55:15But this has actually preserved it.
0:55:15 > 0:55:17It's stopped the reactions taking place,
0:55:17 > 0:55:19the normal reactions where things go bad,
0:55:19 > 0:55:21reactions taking place in the cells.
0:55:21 > 0:55:23If we remove the water, they can't happen.
0:55:23 > 0:55:26And, well, maybe this could be a way of preserving our good looks,
0:55:26 > 0:55:28if we just remove the water?
0:55:28 > 0:55:30Well, you could, and this is what you might look like.
0:55:30 > 0:55:34- LAUGHTER - Well, this chap might not look too good,
0:55:34 > 0:55:38but he is 800 years old, which is quite remarkable!
0:55:38 > 0:55:41And the reason he's survived looking like this
0:55:41 > 0:55:44is because all the water was removed when he died.
0:55:44 > 0:55:46He died in the north coast of Peru.
0:55:46 > 0:55:48It's very dry there, and removing the water
0:55:48 > 0:55:51has actually preserved the cells of his body.
0:55:51 > 0:55:55So maybe, then, this does give us a clue to eternal life -
0:55:55 > 0:55:58Remove the water and you can live a long time -
0:55:58 > 0:55:59well, looking like that -
0:55:59 > 0:56:03but, of course, we need water for our reactions to take place,
0:56:03 > 0:56:07and so, well, I certainly know which one I'm going to choose.
0:56:07 > 0:56:09I think I'm going to stick to
0:56:09 > 0:56:12keeping drinking the water and staying alive.
0:56:12 > 0:56:14Mmm! Freshly synthesised water, delicious!
0:56:14 > 0:56:18And I think, actually, it's time for you to all have some
0:56:18 > 0:56:21freshly synthesised water, as well.
0:56:21 > 0:56:25So you may have noticed that all around the lecture theatre
0:56:25 > 0:56:27here is this very long tube.
0:56:27 > 0:56:30This is over half a kilometre of tubing,
0:56:30 > 0:56:34filled with hydrogen and oxygen in the right proportions to make water.
0:56:34 > 0:56:37So we're going to synthesise some water now.
0:56:37 > 0:56:41So I need the end of the tubes, please. OK, here they come.
0:56:41 > 0:56:43Excellent. Thank you very much.
0:56:43 > 0:56:45APPLAUSE
0:56:50 > 0:56:52OK, now, the ends have some corks in
0:56:52 > 0:56:54and we don't want to fire these into our audience,
0:56:54 > 0:56:57so we're going to fire them into this bucket of water.
0:56:57 > 0:57:00AUDIENCE: Aw! HE LAUGHS
0:57:00 > 0:57:03No, don't say "Aw!" - you wouldn't want this! I can assure you!
0:57:03 > 0:57:06Right, OK. But before I do this, though,
0:57:06 > 0:57:08before we do this final thing here,
0:57:08 > 0:57:10I hope you don't feel too disappointed
0:57:10 > 0:57:14that we haven't found the secret to eternal youth.
0:57:14 > 0:57:17But we have discovered a whole host of exciting elements
0:57:17 > 0:57:19in that one glass of water.
0:57:19 > 0:57:21Some of these elements were deadly toxic
0:57:21 > 0:57:23and others were explosive metals.
0:57:23 > 0:57:25In the next lecture, we're going to find out
0:57:25 > 0:57:29how chemists are trying to extract exciting elements from the Earth.
0:57:29 > 0:57:31These are elements that have been
0:57:31 > 0:57:34trapped in rocks for billions of years.
0:57:34 > 0:57:35And we'll also try to solve
0:57:35 > 0:57:38the biggest alchemical mystery of them all,
0:57:38 > 0:57:40how to turn lead into gold.
0:57:40 > 0:57:42But before we finish, though,
0:57:42 > 0:57:47I think it's time for everyone to get their freshly synthesised water.
0:57:47 > 0:57:48So we'll have...
0:57:48 > 0:57:50Yes, I need to move this from here!
0:57:50 > 0:57:54OK, and we'll have a countdown from three when you're ready.
0:57:54 > 0:57:56So we're just going to aim these.
0:57:56 > 0:57:58And if we have the lights down? OK.
0:57:58 > 0:58:02So, you might want to be looking up, rather than down at us.
0:58:02 > 0:58:04OK, you look up at the pipe.
0:58:04 > 0:58:06OK, so, three, two, one!
0:58:07 > 0:58:10EXPLOSION SCREAMS
0:58:10 > 0:58:12- HE LAUGHS - Thank you very much!
0:58:12 > 0:58:15- APPLAUSE AND CHEERING - Good night, thank you!
0:58:44 > 0:58:48Subtitles by Red Bee Media Ltd