00:00:00 Ladies and gentlemen, boys and girls, children of all ages, please welcome Professor Bassam

00:00:24 Z. Shakhashiri.

00:00:31 Hello, everyone, and welcome to my lab.

00:00:46 I'm very happy to have you here.

00:00:47 Are you ready to learn?

00:00:48 Yes.

00:00:49 Are you ready to have fun?

00:00:50 Yes.

00:00:51 Well, you know, we must do the experiments in a very safe way.

00:00:56 That's why I put my goggles to protect my eyes from potential damage before I did that

00:01:03 experiment.

00:01:04 I also want you to see that we have a fire extinguisher ready to be used just in case

00:01:09 something goes out of control.

00:01:11 We're not planning on anything going out of control, but it's a safety measure that we

00:01:15 are taking.

00:01:16 Now, you notice that the balloon that I brought in had in it a gas lighter than air.

00:01:23 That gas also exploded when I put the flame to it.

00:01:28 Some gases burn and some other gases don't burn.

00:01:31 But what we like to do in science whenever we do an experiment is repeat the experiment.

00:01:37 And that's what we're going to do now, but instead of using this as a lighter, I'm going

00:01:41 to use a gas called natural gas and this torch as the way by which I'm going to ignite

00:01:51 the balloon.

00:01:53 So we've got another green balloon, and what we're going to do is repeat the experiment

00:01:58 in the dark.

00:01:59 So here we go.

00:02:02 Watch and see.

00:02:04 Now with the lights up, you are able to see that experiment somewhat differently in the

00:02:17 dark than it was with the lights on.

00:02:19 Let's take a look at that last experiment in slow motion.

00:02:24 So watch the monitor.

00:02:25 There's the balloon.

00:02:26 Oops, there's the flame actually, not just the balloon.

00:02:30 And that is the replay in slow motion.

00:02:34 Now that balloon had in it hydrogen gas.

00:02:37 Let's move on and do an experiment with this yellow balloon that has in it a gas lighter

00:02:45 than air.

00:02:46 So I'll put the torch to it.

00:02:48 Oops, what happened?

00:02:50 What do you mean nothing?

00:02:53 The balloon popped, but there was no flame, right?

00:02:57 That's because the gas in that balloon is helium, and helium is one of the gases that

00:03:02 does not burn.

00:03:04 Now we've learned so far that some gases burn and some gases don't burn.

00:03:08 Some gases like hydrogen burn and release energy in the form of light, which is what

00:03:12 we saw, but also release energy in the form of sound, which is what we heard.

00:03:19 Before doing the rest of the experiments with the balloons, I'd like for each of us to obey

00:03:24 the safety rules and regulations by protecting our ears from potential damage by taking the

00:03:31 two fingers and putting them in our ears like this so that we protect our ears from potential

00:03:36 damage.

00:03:37 I can't do that and do the experiment at the same time, so I have brought with me some

00:03:43 earplugs.

00:03:44 So I'm going to put the earplugs, and I'd like to ask you to protect your ears very,

00:03:49 very carefully.

00:03:51 If you can hear the sound of my voice, that means your ears are not well protected.

00:03:56 I can't hear you, but I see you smiling.

00:03:58 That means you heard what I said.

00:03:59 So please protect your ears as we go to the next set of balloons and put the torch to

00:04:05 this one.

00:04:17 That balloon had in it a mixture of hydrogen and oxygen.

00:04:22 In other words, there was much more oxygen available for the hydrogen to combine with

00:04:26 in that very, very loud explosion.

00:04:30 Let's repeat that last experiment, but let's repeat it in the dark.

00:04:34 So first let's put our earplugs in.

00:04:37 You protect your ears very well.

00:04:39 So turn the lights down and repeat the experiment in the dark.

00:04:57 We learn more about experiments that release energy in the form of light if we do them

00:05:02 in the dark.

00:05:03 Let's take a look at this last experiment in slow motion.

00:05:06 Watch the monitor and you will see the light coming up to the, there's the torch coming

00:05:13 up to the balloon.

00:05:14 You won't hear any sound.

00:05:16 The flame will hit the balloon and there.

00:05:19 Very fast reaction, very fast explosion.

00:05:24 Well, throughout the years that I have had the privilege of presenting this very special

00:05:33 program to you and to others on public television, I've had also the privilege of working with

00:05:40 some very talented people.

00:05:42 And I would like for you now to welcome one of my colleagues who has been with me for

00:05:46 almost 25 years.

00:05:48 That's Dr. Rodney Schreiner, Rod.

00:06:01 What do we have here?

00:06:02 Well, because this is your 25th anniversary, I thought I'd bring out some things to improve

00:06:08 the celebration.

00:06:09 All right.

00:06:11 And nothing improves a celebration like ice cream.

00:06:14 I agree.

00:06:16 So I brought the ingredients for ice cream.

00:06:20 Okay.

00:06:21 Cream, strawberry preserves, vanilla, sugar, eggs, and a bowl.

00:06:30 And a bowl.

00:06:32 And you want me to help with this?

00:06:33 Yes.

00:06:34 Okay.

00:06:35 What shall I do?

00:06:36 You can open the cream and put it in the bowl.

00:06:37 Open the cream and put it in the bowl.

00:06:38 All right.

00:06:39 It says, thank you for selecting, oh, I won't read the brand here.

00:06:44 Just to open, all right, I open this and put it in the bowl.

00:06:48 All right.

00:06:49 I can do that.

00:06:51 I see you have your goggles on, so that's good.

00:06:53 Well, yes, you never know.

00:06:56 Making ice cream might be hazardous.

00:06:58 Hey, that's a nifty shirt.

00:06:59 Can I get one like that?

00:07:01 Maybe.

00:07:02 Maybe.

00:07:03 All right.

00:07:04 But this one's mine.

00:07:05 You can't have it.

00:07:06 Okay.

00:07:07 That's yours.

00:07:08 What do I do next?

00:07:09 Add the half and half.

00:07:10 Half and half.

00:07:11 Now put the sugar in.

00:07:12 Okay.

00:07:13 Does it make any difference how well you mix this or what?

00:07:19 Well, I need to stir it to dissolve the sugar.

00:07:22 All right.

00:07:24 This is rich ice cream, it sounds rich.

00:07:26 Well, nothing but the best.

00:07:27 All right.

00:07:28 What do I do next?

00:07:29 Well, we're going to need some eggs in here, too, so break the eggs and mix them together.

00:07:44 Mix them together.

00:07:45 Do I need an instrument to mix them together?

00:07:46 Oh, yes.

00:07:47 You got it right here.

00:07:48 Okay.

00:07:49 Fine.

00:07:50 I'll do that.

00:07:51 What's this thing called?

00:07:52 A whisk.

00:07:53 A whisk.

00:07:54 And just whisk it around a little bit, right?

00:07:56 Okay.

00:07:57 How much?

00:07:58 I'm going to put a laboratory apparatus on you.

00:07:59 All right.

00:08:00 Okay.

00:08:01 That looks good.

00:08:02 Now you can pour the eggs into this mixture.

00:08:03 Pour the eggs in there.

00:08:04 And I'll take the whisk from you.

00:08:05 Take the whisk.

00:08:06 You need the whisk.

00:08:07 All right.

00:08:08 Yes.

00:08:09 So now we have the main ingredients for ice cream, the basic mixture.

00:08:10 Yes.

00:08:11 Now we need to flavor it.

00:08:12 All right.

00:08:13 So I brought the vanilla flavoring.

00:08:14 Yes.

00:08:15 How much should I put?

00:08:16 Just dump it in?

00:08:17 No, don't.

00:08:18 Don't.

00:08:19 Don't.

00:08:20 This is a laboratory.

00:08:21 We have to measure.

00:08:22 Measure.

00:08:23 Measure.

00:08:24 Measure.

00:08:25 Measure.

00:08:26 Measure.

00:08:27 We have to measure.

00:08:28 Measure.

00:08:29 And what, how much should I measure?

00:08:30 I have measuring devices here.

00:08:31 One tablespoon.

00:08:32 That's this big one.

00:08:33 That's the big one.

00:08:34 All right.

00:08:35 I know you're used to metric units.

00:08:38 That's 15 milliliters.

00:08:39 Yes.

00:08:40 15 milliliters.

00:08:41 All right.

00:08:42 What's next?

00:08:43 And because this is a very special occasion, I want more than just vanilla ice cream.

00:08:46 Let's add the strawberries to it.

00:08:48 Ah, that's what the strawberries are for.

00:08:49 The strawberry ice cream.

00:08:50 And you even brought a spoon.

00:08:51 That's great.

00:08:53 Now, is this going to be a real ice cream?

00:08:57 I mean, how are we going to do this?

00:08:59 Is it ready to be eaten?

00:09:01 Well, I'm counting on you to have something very cold in your laboratory that we can use

00:09:07 to freeze this.

00:09:08 Something very cold?

00:09:09 Yes.

00:09:10 I have lots of cold things.

00:09:11 I have something really, really cold.

00:09:13 You usually do have cold things.

00:09:14 It's called liquid nitrogen.

00:09:15 Will that do?

00:09:16 That's cold.

00:09:17 That's cold.

00:09:18 All right.

00:09:19 All right.

00:09:20 I've got the liquid nitrogen right here.

00:09:22 But this is really cold.

00:09:23 It's minus 196 degrees Celsius.

00:09:27 Well, that should do it.

00:09:28 That should do it?

00:09:29 That should do it.

00:09:30 Okay.

00:09:33 So, combine the ice cream mix.

00:09:41 Yeah.

00:09:42 Get all these strawberries in here.

00:09:43 Strawberries, that's good.

00:09:44 Yeah.

00:09:45 Okay.

00:09:46 Now, what do I do?

00:09:47 Pour the liquid nitrogen into the pan.

00:09:48 Pour the liquid nitrogen.

00:09:49 That's going to really freeze it.

00:09:50 That's the idea.

00:09:59 Are you sure this is going to be edible?

00:10:01 Absolutely.

00:10:02 Nothing but the best ingredients.

00:10:03 All right.

00:10:07 It's getting stiff.

00:10:08 It's getting stiff.

00:10:09 Okay.

00:10:10 It's more than stiff.

00:10:14 It's getting hard is what's happening.

00:10:17 Oh, it's getting very hard.

00:10:30 Well, when...

00:10:31 It's extremely hard.

00:10:32 It's very hard, but it's also cold, I bet you.

00:10:35 Minus 196, you said.

00:10:37 Right.

00:10:38 Celsius, right.

00:10:39 I don't think I'd want to eat it when it's quite that cold.

00:10:42 Not this cold.

00:10:43 So, what should we do then?

00:10:44 I think I'll take it back and put it in the refrigerator and let it warm up.

00:10:50 But we will get it back, right?

00:10:51 Oh, yes.

00:10:52 Oh, okay.

00:10:53 We'll bring it back.

00:10:54 Well, thank you very much, Rod.

00:11:03 Well, the next experiment that I'm going to do is with another cold substance.

00:11:07 It's not as cold as liquid nitrogen.

00:11:10 This substance is called dry ice.

00:11:12 It's actually solid carbon dioxide.

00:11:14 The temperature of this solid is minus 78 degrees Celsius.

00:11:20 I will use the gloves to protect my hands from frostbite.

00:11:24 Although these are garden variety gloves, they're not very well insulated.

00:11:28 I will not squeeze this or hold it very tightly.

00:11:30 Just pick it up and put a chunk of dry ice on the tabletop.

00:11:34 Dry ice changes from being a solid to a gas directly.

00:11:39 In other words, it doesn't melt.

00:11:42 Substances that do that undergo a process we call sublimation.

00:11:46 There is gas coming off now from the dry ice, but we can't see it.

00:11:50 What I'm going to do next is an experiment with the dry ice

00:11:55 to show that the sublimation is taking place.

00:11:57 Actually, show a few other things, too.

00:11:59 So, I'd like you to focus your attention on this part of the table here

00:12:03 where I have in front of me some cylinders.

00:12:06 These are cylinders that have different colored liquids in them.

00:12:09 How many cylinders do I have?

00:12:13 How many? Ten. Ten cylinders.

00:12:15 As I said, they have different colored liquids in them.

00:12:17 I'm going to put chunks of dry ice in those cylinders in a very special way.

00:12:22 When I get done, you tell me what this special way is.

00:12:24 Here we go.

00:12:26 What's the special way that I'm doing?

00:12:38 Did I put the dry ice in every cylinder?

00:12:40 I put it in every other cylinder.

00:12:42 Lots of interesting things are happening.

00:12:44 You see those bubbles?

00:12:45 Those are gas bubbles.

00:12:46 Those are carbon dioxide gas bubbles.

00:12:49 The carbon dioxide dissolves in the water and forms carbonated water.

00:12:54 We all know about carbonated water because we drink carbonated beverages.

00:12:58 And carbonated beverages have in them carbonic acid.

00:13:02 You also notice that something else very interesting is happening.

00:13:05 Lots of things are happening that are interesting, right?

00:13:08 There is what? A color change that's taking place, right?

00:13:11 What I have here are some dyes that change color as a chemical reaction takes place.

00:13:17 They indicate to us that a chemical reaction has taken place.

00:13:21 They're called indicators.

00:13:23 And the carbonic acid is combining with the different chemicals that are in there.

00:13:27 And they each have their own characteristic colors depending on whether they're acids or bases.

00:13:33 You also notice that coming off the top of those cylinders is something.

00:13:37 What does this look like, this stuff that's coming up?

00:13:39 It looks like foam, but it's not foam.

00:13:41 What does it really look like?

00:13:43 No, steam is invisible. You can't see steam.

00:13:46 It looks like fog. You're right.

00:13:49 And you know what fog is?

00:13:51 Fog is condensed water vapor.

00:13:53 The water vapor is condensing on the carbon dioxide that's coming out from the cylinders.

00:14:00 And you notice that the fog is moving in a downward direction

00:14:04 telling us that carbon dioxide is heavier than air.

00:14:09 So what I want to do next is an experiment with more dry ice.

00:14:14 And I need some hot water.

00:14:16 I don't have any hot water down here.

00:14:18 Could someone please bring me some hot water?

00:14:21 Thank you, Bucky.

00:14:27 And welcome to my lab, Bucky.

00:14:29 So happy to see you here.

00:14:32 You are very, very kind to come to my special silver anniversary.

00:14:36 I know you've been coming every year.

00:14:38 You're one of the best students I've had in my class.

00:14:40 You're a very, very good student.

00:14:42 And I know you are because you have your eye protection.

00:14:46 Bucky is wearing goggles. Yes, so do I.

00:14:49 Yes, and I know you learned that from me.

00:14:51 That's very good, Bucky.

00:14:52 I know you're getting ready for final exams, aren't you?

00:14:58 I hope you are. I hope you are.

00:15:00 I know this is a good... Yes, yes.

00:15:02 You'll do well in the finals, especially if you study for them.

00:15:05 Well, let me do the experiment, Bucky,

00:15:07 that you brought me the hot boiling water for.

00:15:10 This experiment I'll do in this empty dishpan.

00:15:13 It's empty except for air.

00:15:15 What I'll do is I'll pour the water, the hot water, into the dishpan.

00:15:21 You see anything coming off the top?

00:15:23 Now, remember, steam is invisible.

00:15:25 That's not steam.

00:15:27 It's condensed water vapor.

00:15:29 You know, on a very cold day, when you blow your breath on your hand,

00:15:32 don't tell me you see steam.

00:15:34 You're seeing condensed water vapor.

00:15:35 Well, here's the experiment, Bucky, that we're going to do here.

00:15:39 We're going to take lots of dry ice, not just some dry ice,

00:15:42 and pour it into this hot boiling water.

00:15:50 You like that?

00:15:57 This is how they make fog in the movies sometimes.

00:16:00 They take hot boiling water and add dry ice to it.

00:16:03 You notice, once again, that the fog is moving in a downward direction.

00:16:08 Because carbon dioxide is heavier than air.

00:16:13 So, you like that experiment, Bucky?

00:16:15 Yes, I'm glad that you like it.

00:16:20 I have a lot of other experiments that I think you will like,

00:16:24 and I would like to ask you, I know you have to study for your finals,

00:16:27 but can you stay for the rest of the show?

00:16:29 Do you want Bucky to stay?

00:16:31 All right, Bucky.

00:16:33 I've got a special seat set for you right over there.

00:16:36 All right, Bucky.

00:16:38 Make yourself comfortable and keep those goggles on.

00:16:41 And what I have here is a big cylinder of helium,

00:16:46 and what I'd like to do is repeat one of the most favorite demonstrations

00:16:51 that I've been doing in the past six years for this lecture.

00:16:55 So, here we go.

00:17:07 Good evening, hockey fans.

00:17:16 Good evening, hockey fans.

00:17:25 And this is a physiological effect.

00:17:31 Are we back?

00:17:33 Which, among other things, makes people very dizzy

00:17:36 if you inhale a lot of helium,

00:17:37 because, of course, you're replacing the oxygen

00:17:39 that is so very important to my life with helium.

00:17:43 So, I think we will do no more of that demonstration.

00:17:48 I'm going to take a large can.

00:17:53 I'm going to take this cafeteria tray, too, and put it right here.

00:17:56 Take a large can that has an opening.

00:17:59 It's empty except for air.

00:18:02 And I'm going to put a little bit of water in it, like so.

00:18:09 And then I'm going to heat the water.

00:18:12 I'm going to try to boil the water by putting the can on top of this tripod,

00:18:18 below which is a burner.

00:18:21 I'll turn the gas jet on and strike a match and light it.

00:18:26 What I want to do is allow enough time to pass so that the water boils.

00:18:32 When the water boils, we're going to see something coming out of the opening.

00:18:36 It's going to be the condensed water vapor that we will see.

00:18:39 So, we'll get that going.

00:18:41 I also want to get something else going at this end of the table.

00:18:45 I have a beaker that has a volume of two liters.

00:18:48 In it is a sheet of copper that has been cut in the shape of a tree.

00:18:53 And I'm going to add to that a clear and colorless liquid to cover the tree.

00:19:08 We'll come back and take a look at this reaction

00:19:11 and see if anything is happening as we move on to do other experiments.

00:19:19 What I want to do then as we're waiting for something to happen

00:19:22 is to ask you to focus your attention at these two large flasks that I have.

00:19:28 The bottom flask is filled with water.

00:19:31 It has a volume of five liters.

00:19:34 And the top flask looks empty.

00:19:38 It's actually not empty.

00:19:39 It has in it a colorless gas.

00:19:41 It's invisible.

00:19:43 The name of the gas we have in here is called ammonia.

00:19:47 Now, this flask that's filled with ammonia, which we cannot see,

00:19:50 is connected to the bottom flask by a piece of glass tubing

00:19:54 running through this two-hole rubber stopper.

00:19:57 And the other hole has in it the bottom of a medicine dropper and this rubber bulb.

00:20:06 The rubber bulb has some water in it.

00:20:08 What I'm going to do is squeeze the bulb

00:20:11 so I can squirt some water into the top flask and see if anything happens.

00:20:16 That's why we do experiments.

00:20:17 We mix things together to see if anything happens

00:20:19 and we try to be attentive about it.

00:20:21 So here we go.

00:20:22 I squeeze this.

00:20:39 What you see happening here is the siphoning of the water

00:20:42 from the bottom flask to the top flask.

00:20:45 That happened because ammonia, the gas ammonia, dissolves in water.

00:20:51 And the small amount of water I squeezed out of the rubber bulb here

00:20:56 dissolved all the ammonia that was filling up the top flask

00:21:00 and created a partial vacuum up there

00:21:02 causing the water to be siphoned from the bottom flask to the top flask.

00:21:07 And we have an indicator in here to indicate to us

00:21:10 that ammonia forms a basic solution when it dissolves in the water.

00:21:16 So this is a kind of an interesting experiment

00:21:18 that has to do with the effect of the solubility of a gas

00:21:22 and then the fact that the atmospheric pressure pushes on the water

00:21:27 and causes the siphon to go up.

00:21:30 All right.

00:21:31 Let's see if we can in the next few moments

00:21:37 do some of the favorite experiments that I've done in previous programs.

00:21:42 And I get a lot of mail about the experiments.

00:21:44 I wish I could repeat all of them.

00:21:46 But I'm going to just do a couple right now very quickly.

00:21:49 The first one has to do with reaching into my wallet

00:21:52 and seeing what I have in my wallet.

00:21:54 Oops.

00:21:55 I see that I have a dollar bill in my wallet.

00:21:57 I'm going to take this dollar bill and put it in the flame.

00:22:01 And did you see that?

00:22:04 Was that too fast?

00:22:06 Well, you know what we should do.

00:22:09 What we always do is repeat the experiment.

00:22:12 So I'll do it now more slowly.

00:22:14 I'll take what looks like a dollar bill.

00:22:17 It's not a real dollar bill.

00:22:18 It's a phony dollar bill.

00:22:19 It's a fake dollar bill.

00:22:21 This dollar bill, this fake dollar bill,

00:22:23 has been made of paper that has been especially treated

00:22:26 so that when it burns it doesn't leave any ash behind.

00:22:30 So let's repeat the experiment now.

00:22:32 Go to the flame.

00:22:34 And as soon as it touches it, there, it disappears into thin air.

00:22:39 OK.

00:22:40 I'm glad you like that.

00:22:46 Well, let me see what else I have in my wallet.

00:22:49 I have a $20 bill.

00:22:51 And this is a real $20 bill.

00:22:54 You suppose I can do the same thing as I did with that?

00:22:57 No, no?

00:22:58 Well, I'll tell you what.

00:22:59 What I want to do is take this jar that has in it a clear and colorless liquid.

00:23:06 What do you suppose this liquid is?

00:23:08 What does it look like?

00:23:09 It looks like water.

00:23:10 So let's see what happens.

00:23:14 When I take the $20 bill, I just soak it in this liquid.

00:23:17 I have a pair of tongs here to help me fish it out.

00:23:21 I'll soak it in and fish it out.

00:23:23 You see it's dripping like any wet object would or does.

00:23:28 And I take this to the flame and there's a $20 bill on fire.

00:23:34 Or is it?

00:23:35 You did see a flame, right?

00:23:37 $20 bill is intact.

00:23:39 So could this liquid be water?

00:23:42 No.

00:23:43 This liquid, I will tell you what this liquid is.

00:23:45 This is a mixture of something we call rubbing alcohol and water.

00:23:49 This is a 50% mixture.

00:23:51 Rubbing alcohol you can get in the drugstore and water you can get anywhere.

00:23:56 But it's the alcohol that was burning.

00:23:58 That flame that we saw was from the burning of the alcohol.

00:24:02 And this experiment tells us that alcohol, this alcohol, burns at a temperature lower

00:24:09 than the temperature at which the paper from which this $20 bill is made.

00:24:14 Well, this is a good $20 bill.

00:24:15 I'm going to put it back in my wallet before something else happens to it.

00:24:19 I'll close this jar and move on to do another experiment that we've done before

00:24:27 and a lot of people like it.

00:24:29 This experiment, let's see, I need to connect the hose to the gas jet

00:24:36 so I can then light the burner.

00:24:41 And take a match, light the burner.

00:24:43 There is a lit burner before us.

00:24:47 And what I'm going to do is take out of this small squeeze bottle a powder

00:24:54 and squeeze it into the flame.

00:25:00 Isn't that neat?

00:25:06 This powder is called lycopodium powder.

00:25:09 It's a finely divided powder.

00:25:11 It's dust, almost dust.

00:25:13 You know sometimes we hear about explosions, dust explosions that happen in silos.

00:25:19 That's because the corn or whatever else is being stored in the silo changes.

00:25:24 Some of it changes into dust and it catches on fire very, very rapidly just like this one did.

00:25:30 Okay, let's take a look at what's happening over here

00:25:35 and see if we can see any condensed water vapor coming out.

00:25:37 Can you see any condensed water vapor coming out?

00:25:40 Let's make sure this is really going hot.

00:25:44 You see some? There's some coming out.

00:25:46 Some evidence that this is going on.

00:25:50 So what I want to do is use this cafeteria tray to put some ordinary ice in it.

00:25:56 Just going to put some ordinary ice in here

00:25:59 because I want to use this ordinary ice to cool the can.

00:26:09 And to do that I can't handle the cans with my bare hands because the can is very hot.

00:26:14 I'm going to put my gloves on again to protect my hands this time from heat, not from cold.

00:26:21 And to do this experiment I will take a rubber stopper and plug up the hole that's up there.

00:26:28 And what I will do is plug it up like so, lift it up and put it on the ice.

00:26:34 And we'll see what happens.

00:26:49 The can got crushed.

00:26:51 That's because the pressure inside the can got to be less than atmospheric pressure.

00:26:58 And the question is how did that happen?

00:27:00 Well, you know what?

00:27:01 You can do this very same experiment at home but you don't need a big can like this.

00:27:06 All you need is an empty soda can like this that you've emptied.

00:27:11 You put a little bit of water in it as I'll show you now.

00:27:17 And you put it so that the water boils off.

00:27:20 And what are we looking for?

00:27:22 We're looking for evidence that the water has boiled.

00:27:25 And what we're looking for is condensed water vapor coming out of there.

00:27:29 So it takes a little while for that to happen.

00:27:31 So we're waiting for that to happen.

00:27:33 But we'll try to talk about why this happened.

00:27:37 The pressure of the atmosphere caused the can to collapse, to be crushed.

00:27:41 And this happened when I, after heating the water and the water changed into vapor,

00:27:47 the vapor was coming out of the hole of the opening.

00:27:51 And along with it, it swept, that vapor swept along with it some air.

00:27:55 And when the air was swept out and then I sealed it by putting the rubber stopper on,

00:28:00 then I put it, I cooled it off on the ice tray.

00:28:05 Then the water condensed and the pressure inside the can got to be less than the pressure outside the can.

00:28:11 So this is happening over here.

00:28:13 So what's happening is that the pressure inside the can now is different.

00:28:17 But I can't handle it with my hands because it's very, very hot.

00:28:21 So I'll take these tongs.

00:28:23 And I'll pick up the can.

00:28:25 And I'm going to flip it over and put it in this beaker.

00:28:28 It has water in it.

00:28:30 And we'll see what happens.

00:28:32 So here we go.

00:28:37 You see the can?

00:28:46 Got crushed.

00:28:48 And for the same reason we had before, the can was not very clean.

00:28:51 That's why the water is that color.

00:28:54 All right.

00:28:56 What I'd like to do now is another experiment.

00:28:58 But to help me do this experiment, I'd like to call on one of our expert lecture demonstrators, Fred Juergens.

00:29:04 So Fred, won't you please come out?

00:29:13 So we've got a big, long glass tube here that's filled with a mixture of colorless gases.

00:29:19 And there's a little bit of water in there, too.

00:29:21 You might be able to see some water droplets on the inside of the tube.

00:29:25 And the experiment that we're going to do involves finding out whether the gases that are in here will put out a burning match

00:29:33 or whether they will allow the match to continue to burn.

00:29:37 So what I'm going to do is I'm going to get up here on this step stool.

00:29:40 And then I'm going to light the match.

00:29:42 And then I'm going to ask that the lights be turned out.

00:29:46 And we're going to drop this burning match down into this tube and see what happens.

00:29:50 Everybody ready?

00:29:52 Here we go.

00:29:54 Wow.

00:30:05 Well, it's very clear that the match has gone out, right?

00:30:10 But we had quite a flame in the process.

00:30:13 And one of the products of the reaction that went on is the element sulfur.

00:30:18 And that's why this yellow coating is on the inside of this tube now.

00:30:21 Before, it wasn't yellow.

00:30:23 Sulfur is a yellow element.

00:30:25 And before, it was present in a combined form so that you couldn't see its color.

00:30:29 But now you can see the color of the element sulfur.

00:30:32 So I'm going to take this away and clean it up now because the sulfur really sticks to the glass if you don't clean it out quickly.

00:30:37 So we'll see you.

00:30:38 Thank you, Fred.

00:30:44 Let's take a quick look at this last experiment in slow motion.

00:30:48 So watch the monitor.

00:30:50 And you won't hear the sound again.

00:30:51 There's the match that Fred is holding.

00:30:54 It's being dropped.

00:30:56 And there's that big flame.

00:30:58 And you see Fred trying to get out of the way there.

00:31:06 Sometimes in my lab, I get very, very big surprises.

00:31:10 And I would like to ask you to welcome a very special friend of mine who has been helping out with these programs for many, many years.

00:31:19 Is Elizabeth in the audience?

00:31:22 Come on up, Elizabeth.

00:31:28 Hi.

00:31:29 Hi.

00:31:30 How are you?

00:31:31 Fine.

00:31:32 I brought you a special token because it's your 25th anniversary.

00:31:35 How sweet of you.

00:31:36 And how special of you.

00:31:37 This is a very, very nice token.

00:31:39 Do you know what metal it's made of?

00:31:41 Copper.

00:31:42 It is made of copper.

00:31:43 You're right.

00:31:44 And do you suppose we can try to change copper to silver?

00:31:50 This is the silver anniversary of the show.

00:31:52 Do you suppose we can try to do that?

00:31:53 Sure.

00:31:54 Would you like to try?

00:31:55 Yeah.

00:31:56 Okay.

00:31:57 Well, what's the first thing we must do before trying?

00:31:59 Put on our goggles.

00:32:00 Well, I got mine on.

00:32:01 So you put yours on.

00:32:03 We're going to do this experiment to try to change copper to silver by putting it in this casserole.

00:32:10 That's empty.

00:32:11 You see that?

00:32:12 Put this in the casserole.

00:32:13 Put it on top of the burner.

00:32:15 And then add a clear and colorless liquid just to cover it up.

00:32:22 And after that, what we are going to do, what I'm going to do is add a solid, a metallic solid.

00:32:31 And we'll have to just to cover it up.

00:32:36 And then I'm going to take a match, strike the match.

00:32:41 After I turn the gas on, strike the match, right?

00:32:44 That's the proper way of doing it.

00:32:45 And, of course, we always strike the match away from us.

00:32:48 So we'll let it heat for a while.

00:32:51 You know, chemical reactions sometimes are very, very fast and sometimes take a while to happen.

00:32:57 And that's why we have to heat them up to make them go faster.

00:33:00 We'll wait for that for a while and see what else we might want to do here.

00:33:05 Okay.

00:33:06 Well, I see you have another yellow balloon.

00:33:09 Is there anything else you can do with it?

00:33:11 Oh, sure.

00:33:12 I can do lots of things with balloons.

00:33:14 This is a yellow balloon that has in it the gas helium.

00:33:17 And what I'm going to do with this balloon is to add to it something that's left over from the ice cream experiment.

00:33:27 What's left over from the ice cream experiment is some liquid nitrogen.

00:33:31 So I'm going to put the balloon in this large dish like so.

00:33:36 I can't hold it.

00:33:38 I can't let go of it because it'll go up, so I'll just hold it down like this.

00:33:41 And then I'm going to add the liquid nitrogen to it and we'll see what happens.

00:33:46 You ready?

00:33:47 Yep.

00:33:48 Okay.

00:33:49 Oh, I see some of you are covering your ears.

00:33:51 Why are you doing that?

00:33:54 Okay.

00:33:55 I know why you're doing it because you've had experience with balloons.

00:33:57 So here's the liquid nitrogen and you see what happens.

00:34:01 The balloon, what's happening to the balloon, Elizabeth?

00:34:04 It's shrinking.

00:34:05 You bet it's shrinking.

00:34:06 It's shrinking and collapsing because the pressure inside is lower than the pressure outside.

00:34:12 We cooled down the helium and the helium slowed down to the point where it exerts less pressure than it did before.

00:34:21 And when the balloon warms up, then it goes all the way to the ceiling.

00:34:28 Almost got a hit there, right?

00:34:30 Yep.

00:34:37 I'd like you to walk over to that bicycle wheel that we have at this end of the table.

00:34:43 Do you see anything special about it?

00:34:45 There aren't any metal spokes.

00:34:47 They've all been replaced with pieces of rubber tubing.

00:34:50 That's right.

00:34:51 And what we want to do is learn something about the properties of rubber when rubber gets heated.

00:34:58 Behind the wheel, we have a heat lamp.

00:35:02 And if you throw the switch on, then you can turn the light on and we'll see what happens.

00:35:06 Is this it?

00:35:07 Yeah.

00:35:08 Okay.

00:35:10 The light is on, right?

00:35:12 Yeah.

00:35:15 Do you see anything happening?

00:35:16 The wheel's starting to turn.

00:35:21 Are you pushing it?

00:35:23 No, I'm not touching it.

00:35:25 Nobody's touching it, right?

00:35:26 So the wheel, this is a well-balanced wheel where the metal spokes have been replaced by pieces of rubber tubing.

00:35:33 And as the rubber tubing is heated, then it makes the wheel turn.

00:35:38 So you and I are going to do an experiment to try to understand why that happens.

00:35:42 And this experiment we will do with rubber bands.

00:35:45 Here's one rubber band for you and one for me.

00:35:48 And the way in which we will do this experiment is that we will use our forehead as a way of measuring heat flow in and out of a rubber band.

00:35:56 Okay?

00:35:57 So hold it up like this right close to your forehead and touch your forehead.

00:36:01 What does it feel like?

00:36:02 It feels cool.

00:36:03 Okay.

00:36:04 Now take it forward a little bit, stretch it, and quickly put it on your forehead.

00:36:07 What does that feel like?

00:36:08 It feels warm.

00:36:09 Right.

00:36:10 So stretching the rubber band gives off heat, right?

00:36:13 Now take it forward, allow it to shrink, and touch your forehead.

00:36:18 What does that feel like?

00:36:19 Cool.

00:36:20 It feels cool again, right?

00:36:21 So stretching the rubber makes the rubber hot, right?

00:36:25 And allowing the rubber to shrink makes it cold.

00:36:28 So if we heat rubber, what's going to happen to it?

00:36:31 It's going to shrink.

00:36:32 And that is the explanation that helps us with the bicycle wheel that we have over there.

00:36:40 Okay?

00:36:41 So you learned a few things about rubber you probably didn't know before.

00:36:43 Yeah.

00:36:44 Yeah, but you knew about this part, right?

00:36:46 Yeah.

00:36:47 Yeah, right.

00:36:48 Okay.

00:36:49 Great.

00:36:50 Shall we take a look and see what's happening to our experiment over here?

00:36:55 Okay.

00:36:56 Let's do that.

00:36:59 And I need to fish it out.

00:37:00 It's very, very hot.

00:37:01 Let me turn the heat off.

00:37:06 Ooh.

00:37:09 I'll have this beaker.

00:37:11 Let me just clean it off and cool it down.

00:37:20 And there we have a piece of what looks like it is silvery in color, but it really isn't silver.

00:37:29 Because the experiment that I did here, I used the copper that you gave me, the copper token.

00:37:35 I added some zinc chloride to it and some zinc.

00:37:38 And the zinc deposited on the copper and gave it this silvery look.

00:37:42 So this is not real silver.

00:37:44 Okay?

00:37:45 Okay.

00:37:46 All right.

00:37:47 But thank you again for the token that you gave me here.

00:37:48 It's very, very kind of you.

00:37:49 You gave me that.

00:37:54 Does that thing over there have anything to do with your silver anniversary?

00:37:59 That flask that's silvery?

00:38:01 Well, yes, it does.

00:38:05 Is there something that you'd like me to do to it or do with it?

00:38:07 I'll just set it over here.

00:38:09 Can you pull off the rubber stopper?

00:38:11 You mean just open it up?

00:38:13 Yeah.

00:38:14 I can open it up very easily.

00:38:15 Just take the rubber stopper off, as you suggested.

00:38:24 That looks like a genie.

00:38:26 Right?

00:38:27 Yeah.

00:38:29 That's neat.

00:38:30 You like that, huh?

00:38:31 I'll tell you what was in here.

00:38:33 We had some hydrogen peroxide, very strong, concentrated hydrogen peroxide.

00:38:38 And we had a small teabag that was held by a very fine thread.

00:38:43 And when I took the rubber stopper off, the thread, the bag fell in

00:38:49 because the thread wasn't being held again and started this reaction.

00:38:53 Was there tea in the teabag?

00:38:55 Oh, no.

00:38:56 It was not a teabag.

00:38:57 It was just like a teabag.

00:38:58 What we had in there was some manganese dioxide.

00:39:01 And that manganese dioxide catalyzes the decomposition of the hydrogen peroxide.

00:39:06 Okay.

00:39:07 Well, thank you, Elizabeth, very much.

00:39:09 You're welcome.

00:39:10 And I hope you enjoy the rest of the show.

00:39:11 Thank you very much.

00:39:16 And what we're going to do is use this tall beaker

00:39:20 and take two liquids out of these two small vials.

00:39:24 This beaker has a volume of about one liter.

00:39:28 And we're going to mix this first liquid that looks like what?

00:39:34 It looks like, yeah, caramel molasses, but it isn't.

00:39:37 It's a very poisonous liquid.

00:39:39 We should not at all touch it by hand or even –

00:39:43 well, we shouldn't touch it by hand for sure, for sure,

00:39:45 and we should not put it close to our mouth.

00:39:47 Here's another liquid that looked like what?

00:39:51 Honey, yeah, or syrup, something like that.

00:39:54 And we're going to mix those two liquids together like so.

00:40:01 And I want you to watch very carefully what happens.

00:40:05 You know, in chemistry, unless you mix the chemicals, no reaction happens.

00:40:11 Sometimes it happens fast.

00:40:13 Sometimes it takes a while for it to happen.

00:40:16 You see there is a very big change taking place here, right?

00:40:21 Wait a minute now.

00:40:22 This stuff is coming – wait a minute, wait a minute.

00:40:42 No, I did not expect this to happen.

00:40:45 Now, this is a polymer that we call polyurethane foam,

00:40:51 and it is produced by simply mixing those two chemicals together as I have done.

00:40:58 I want you to notice – of course, you've already seen this –

00:41:01 I want you to notice the tremendous change in volume that took place.

00:41:05 Something else I want you to notice, when I pick this up and turn it around,

00:41:10 it doesn't fall off.

00:41:11 It has become a very rigid substance.

00:41:15 Look, we can beat up on it here.

00:41:18 It has become quite solid.

00:41:21 What we should do now is take a look at that beaker that I filled.

00:41:24 The beaker had the piece of copper in it before,

00:41:27 that I filled with the clear and colorless liquid.

00:41:30 And what we're beginning to see here is the outline of a silver-coated tree.

00:41:36 That's because the liquid I used was silver nitrate,

00:41:40 and the chemical reaction between the silver nitrate and the copper

00:41:43 caused the deposition of silver on the copper.

00:41:47 You see the solution is developing its own characteristic color.

00:41:50 That's because the copper is going into solution.

00:41:55 Well, this being the silver anniversary of the program

00:42:00 caused me to go back and look to see if I had some notes

00:42:05 and some objects from 25 years ago or so.

00:42:08 And I did find some.

00:42:09 I actually found these silver spoons, and they're tarnished.

00:42:13 And what I'd like to show you is how we can remove the tarnish.

00:42:17 We can remove the tarnish very easily if we use a commercial solution.

00:42:22 Here's a tarnished spoon.

00:42:26 All we have to do is dip it into the solution.

00:42:32 And you see very quickly the tarnish was removed.

00:42:36 The tarnish is a compound between silver and sulfur.

00:42:40 It's called silver sulfide.

00:42:42 And sulfides are in the air.

00:42:44 They're in substances like eggs and so on.

00:42:46 And they can be removed by using this commercial method of removal,

00:42:52 the tarnish removal.

00:42:54 I'll clean it off a little bit here so it's easy to handle.

00:42:58 There's another way to do this, a very simple way.

00:43:00 What you need is an aluminum pan.

00:43:03 And if you don't have an aluminum pan,

00:43:05 you just take any pan and line it up with some aluminum foil.

00:43:08 And the next thing that you need is some baking soda.

00:43:11 The third thing that you need is some hot boiling water,

00:43:14 which I have right here.

00:43:18 And I'll get it out.

00:43:22 And I will take then some of the sodium carbonate that we have here,

00:43:31 bicarbonate, and put it into the boiling water like so.

00:43:38 And then take a spoon that needs to be cleaned out,

00:43:42 a silver spoon that's tarnished,

00:43:44 and add the hot water that has the baking soda in it

00:43:55 so that we cover it.

00:44:00 And you see that we can remove the tarnish just as easily

00:44:03 because of a chemical reaction taking place between the aluminum

00:44:06 and the silver sulfide, the silver and the silver sulfide.

00:44:11 All right, now I want to do an experiment right over here

00:44:17 with a large flask.

00:44:23 I want to empty the water out of this flask.

00:44:28 You know in chemistry we'll mix things together

00:44:31 and we'll see what happens.

00:44:33 Sometimes something happens right away.

00:44:35 Sometimes it takes a while for something to happen.

00:44:37 So here's the first ingredient.

00:44:40 Here's the second set of ingredients that I will add to this flask.

00:44:46 I'll put the stopper on and start mixing the chemicals together

00:44:51 and we'll see what happens.

00:44:55 We already see something happening.

00:44:57 The clear and colorless liquids are no longer clear or colorless

00:45:02 and something else is happening, right?

00:45:16 I can see myself in this silver mirror.

00:45:20 This is the way in which mirrors sometimes are made.

00:45:26 And sometimes we make ornaments the same way too, right?

00:45:31 And I'd like to show you a very, whoops, here it is,

00:45:38 special ornament that I made just prior to your coming into this show.

00:45:46 The silver in there is deposited as a thin layer on the inside of the flask.

00:45:52 Let's take another look at the tree that we have inside the beaker

00:45:58 and see how the white silver now is beginning to deposit.

00:46:03 Isn't that pretty?

00:46:05 Let me take this box here out of the way.

00:46:07 There you see it is an interesting display

00:46:12 for the chemical reaction between copper and silver.

00:46:18 Now let's take a look at this large beaker.

00:46:23 It has a volume of four liters.

00:46:25 I want everybody to look at this beaker

00:46:27 because if you look at this beaker,

00:46:29 and I just told you its volume is four liters,

00:46:32 you've learned how big four liters is.

00:46:34 You can't unlearn it.

00:46:36 You may forget it, but you can't unlearn it.

00:46:38 This is how big four liters is.

00:46:39 And I have three and a half liters of water in there

00:46:41 and I have a stirrer.

00:46:44 And I'm going to stir the water by turning the motor on.

00:46:52 And then I'm going to add a clear and colorless liquid

00:46:57 and a clear but slightly colored liquid into the vortex

00:47:02 that's developing here.

00:47:03 We'll see what happens, if anything happens.

00:47:12 What does that look like?

00:47:14 Looks like a tornado.

00:47:15 You're right.

00:47:16 That's why we call this experiment the tornado experiment.

00:47:20 What color is this tornado?

00:47:23 We call this the orange tornado experiment.

00:47:27 Okay, let's add more of this.

00:47:28 Let's see what happens if we add more.

00:47:33 And now it's more like a hurricane, right?

00:47:36 And we add more of this.

00:47:38 And what happens?

00:47:40 More is better?

00:47:42 Not always, right?

00:47:44 But now it disappears.

00:47:45 Add a little bit of this.

00:47:49 I thought you said it's orange.

00:47:52 Well, it starts out being yellow and now it turns into yellow.

00:47:56 Was it orange?

00:47:57 Or is it orange or yellow now?

00:47:58 See, that's why we do experiments

00:48:01 and we make observations about the experiments

00:48:03 and try to learn about the behavior of different substances that we have.

00:48:09 Okay.

00:48:14 What I want to do now is use the same stirrer

00:48:18 to do another experiment with another beaker whose volume is?

00:48:23 Four liters.

00:48:25 Right.

00:48:26 Four liters.

00:48:27 You've got that right.

00:48:28 It has a stirrer in it.

00:48:29 It's empty except for air and the stirrer.

00:48:31 And I'm going to mix into this beaker three different liquids.

00:48:34 Here's the first one.

00:48:38 Here's the second one.

00:48:40 Anything exciting happen so far?

00:48:43 Not really, right?

00:48:44 So the volume changed.

00:48:46 Well, here's the third one.

00:48:52 This is an example of what we call a chemical oscillating reaction.

00:49:10 It has eight or nine different chemicals including?

00:49:14 You're not paying attention to what I'm saying to you.

00:49:17 I know how exciting it is to see chemicals in action.

00:49:20 Yes.

00:49:21 This is called the Briggs-Rauscher reaction.

00:49:24 It's named after two high school teachers who discovered it in 1973.

00:49:28 And it has in it eight or nine different chemicals

00:49:30 including water, potassium iodate, sulfuric acid, manganese sulfate,

00:49:35 potato starch, hydrogen peroxide, and a few others.

00:49:39 And the yellow color that you see, not right now,

00:49:42 but when they oscillate, that yellow color that you see right there

00:49:45 is the color of what we call iodine or in the vernacular iodine.

00:49:49 And then it combines with the potato starch

00:49:51 to form this deep blue color that's almost black.

00:49:54 And these oscillations continue for a period of time.

00:49:58 And this is what makes science fascinating and interesting

00:50:02 and also challenging in terms of trying to understand

00:50:05 what it is that is going on in a reaction of that type.

00:50:10 Now, what I would like to see and check out on

00:50:14 to see is if the ice cream is ready.

00:50:16 Oh, yeah, it's ready.

00:50:17 Ice cream ready?

00:50:18 Bring it in right now.

00:50:19 Okay.

00:50:20 Here we are.

00:50:22 Here's the ice cream.

00:50:23 Oh, thank you.

00:50:24 You've got some bowls.

00:50:26 There's some bowls and some other things.

00:50:28 Let me set these.

00:50:29 Yeah, let's put those up.

00:50:30 What's this that you've got here?

00:50:32 That's another interesting and colorful set of beakers.

00:50:34 Well, yeah, I was putting together some beakers to make some of the chemicals.

00:50:38 And I was stirring it around.

00:50:41 And I noticed that when I was stirring it, I heard sort of a tone.

00:50:45 And so I started messing around with beakers

00:50:48 and just putting different amounts of water in them

00:50:51 to see if I could make anything that sounded interesting

00:50:54 rather than just explosions and all that kind of stuff.

00:50:57 So here's what I set up.

00:50:59 And I'd like you to listen very carefully

00:51:01 and see if you can tell what's going on here.

00:51:08 This is for Bucky and for the Hall of Fame Bowl, right?

00:51:15 Thank you.

00:51:33 Okay, now cheer for Bucky.

00:51:42 Thank you very much, Fred.

00:51:43 And of course the ice cream is ready.

00:51:45 And here it is.

00:51:46 And let's take some out and put it in this bowl.

00:51:52 And I would like the person to try it for the first time to be Elizabeth.

00:51:57 So I'll bring it over to Elizabeth, see if Elizabeth is willing to try it.

00:52:01 Are you willing to try it?

00:52:02 Yeah.

00:52:03 All right, here you go.

00:52:09 What does it taste like?

00:52:10 It's good.

00:52:11 It's good? What flavor is it?

00:52:12 Strawberry.

00:52:13 Of course it's strawberry.

00:52:14 Thank you, Elizabeth.

00:52:15 Enjoy the rest of it.

00:52:23 What I'd like to do now is a reaction in this special apparatus

00:52:28 that consists of a glass spiral connected to a large glass funnel.

00:52:34 And down at the bottom is a large glass flask.

00:52:37 And I'm going to use a clear and colorless liquid

00:52:41 and mix it with a clear and colored liquid.

00:52:45 But I'm going to do this mixing in the dark.

00:52:47 So here we go.

00:52:48 With the lights off, I'm going to mix those.

00:52:50 There we go.

00:53:04 This is an example.

00:53:05 With the lights up, please.

00:53:06 This is an example of what we call a chemiluminescent reaction.

00:53:10 Chemiluminescence is the phenomenon whereby energy is released in the form of light

00:53:15 but not in the form of heat.

00:53:18 What I would like to do is really express my great appreciation

00:53:22 for your sharing with me the excitement of this very special silver anniversary show.

00:53:27 You've been a very good audience, and I'm very, very thankful for...

00:53:30 Excuse me, Professor Shakasheri.

00:53:32 Yes, Janice?

00:53:33 Fred and I over in the lab have put together just one more little tribute to your anniversary,

00:53:37 and I wonder if you have an extra minute.

00:53:39 Of course we have time for that.

00:53:41 Thank you.

00:53:46 This is Janice Parker, our second expert lecture demonstrator.

00:53:53 Can I have someone turn the lights on, please?

00:54:09 Thank you, Janice.

00:54:10 Thank you, Fred.

00:54:11 That's very special.

00:54:12 That really is.

00:54:14 Happy anniversary.

00:54:15 Thank you very much.

00:54:17 25 wonderful years.

00:54:19 I want to thank you all and urge you to do science and other things that are worthwhile in life,

00:54:24 but don't forget, no matter what you do, science is fun.

00:54:29 Thank you very much.

00:54:31 Thank you very much.

00:54:39 Thank you.

00:55:09 Thank you.

00:55:40 To obtain a VHS video of this program, send a check for $30 to 1994 UW Christmas Lecture,

00:55:49 Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706.

00:55:59 Thank you.

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00:56:32 Thank you.