00:00:00 Professor Shakhashiri said that if I could really be with you this morning that he would let me participate in some of the demonstrations and I certainly wish I could be with you to do that because I know you're going to have in this sixth annual

00:00:29 recurrence of the special chemistry lecture a mighty interesting time. In fact I suspect you've been having a pretty interesting time all semester. Learning something about chemistry is going to be useful to you all your lives even if you aren't going to be professional chemists. You are surrounded by chemical problems in your everyday life and I'm sure that you have during the course of the semester

00:00:59 and you're going to today have a chance to relate basic chemical principles to things that will be a part of your lives in the years to come. You know where it is at in a university is in the classroom. Good teaching and motivated learning are what this university is all about and I like to be in the classroom because that is where the action is in a

00:01:28 university and we admire people like Professor Shakhashiri who make learning exciting as I'm sure you found it to be in this classroom during this semester and I'm sure you're going to remember many of the demonstrations and many of the lessons that you're going to learn today in a very interesting way throughout your life.

00:02:28 Welcome you to this traditional lecture and let's see do I have can you hear me now okay can you hear me now all right here we go all right. As I started to say I'd like to welcome you to this traditional lecture that we have at the end of the first semester. This is as you know the sixth annual lecture. It is a lecture devoted entirely to special demonstrations that I'd like

00:02:58 to do for you and of course I'll be calling on several people to help me do these demonstrations throughout the remainder of this hour. As you know in teaching introductory chemistry courses we are involved in a hierarchy of activities and these activities are very much related to what you learn in the introductory courses. The first level of the hierarchy of the activities of course

00:03:27 deals with facts. We try to teach chemical facts and we hope that you do learn these chemical facts. We also are involved in this teaching learning process in the chemical theories and models of chemical reactions and the ideas that we have about chemical bonding and chemical equilibrium and so on. Another type of activity that we are involved in in this hierarchy deals with skills. This includes laboratory skills as well

00:03:57 as manipulative skills for chemical equations and mathematical equations and various representations of chemical change that takes place. Of course the most important element in this hierarchy is the attitude with which we make these presentations and perhaps even more important than that is the attitude that you the students develop toward chemistry and toward science. And I hope that in this lecture here which culminates the activities that we have been

00:04:27 involved in throughout the semester you will get a flavor of the kinds of things that we have been doing and of course our television audience will also get the same kind of flavor that we have been trying to deal with throughout the semester and also during the upcoming spring semester.

00:04:45 So what I'd like to do in this special lecture is as I said a series of demonstrations that review the various topics that we have talked about in chemistry 103 and also preview a variety of topics that we will be dealing with in chemistry 104. And these topics are not all inclusive but these are some of the topics that we will be dealing with in this lecture series.

00:05:15 Of course whenever we do any chemical activity of any sort involving chemicals we must observe the laboratory safety regulations and I will begin right now by putting on my safety glasses and I also want you to know that I have this fire extinguisher which I hope we will not use but in case we need it, it does work.

00:05:46 I want you to be convinced that it is for real. Some of you have seen this at the football games, right? Whenever Wisconsin scores a touchdown you hear that, right? So it's ready if we need it.

00:06:01 And it's got on it this safety pin which I shall put in right now so it does not get triggered by accident. So it's ready to go right here.

00:06:17 Well, one of the things that we've talked about in this course and one of the most important chemical phenomena that we deal with is the properties of gaseous materials and how these materials behave and sometimes can be liquefied.

00:06:30 In fact we talked for some time about the kinetic molecular theory of gases and I would like to begin the demonstrations now by showing you a gas that is very common but this gas that I'm going to deal with right now is in the liquid form and the gas of course is nitrogen and we have the liquid nitrogen which is kept in this thermos bottle called the Dewar flask.

00:07:00 You see it is a liquid. It's very cold. It has a very low boiling point. It's getting all over the place here. It's a very good device you see for clearing the top of the desk here which is what I want to do now but it's also an expensive device.

00:07:19 Now one thing that we've done in the past and it's always of interest to so many of you to see again is the effect of temperature on the properties of gases and what I have in these three balloons here is a gas of course that is lighter than air.

00:07:36 That's why these balloons are on a string. Of course if I were to let the string go then the balloon will go up to the top of the room but let's see what happens now when I add some liquid nitrogen to the balloon.

00:07:53 And you see the effect is that the gaseous molecules that are inside the balloon have been cooled and the velocity with which they're traveling has been lowered. Of course as it warms up then the gas molecules increase their velocity. Let's just cool it again.

00:08:11 Come on fella cool it. There we go and you see as it warms up as the liquid nitrogen evaporates and the temperature goes up then the balloon which is full of the gas here, what's happening to it?

00:08:31 It goes up in very slow motion and there it goes to the top of the room. Well then the effect of temperature is of course to, well we can do this again since you like that so much let's just do it one more time.

00:08:51 Okay we'll just cool this fella here and we'll try to string them along a little bit here. Let's see what happens. Of course this one is on the string so it doesn't go as high as the other one.

00:09:13 Okay now we can easily make it go high you see.

00:09:42 Now as you know the gas that's in the balloon is lighter than air and it is actually helium and helium is a gas that has other unique properties that are related of course to the molecular weight that the gas has as well as to the temperature as we have just seen here.

00:10:04 What I have here is a big cylinder of helium and what I'd like to do is repeat one of the most favorite demonstrations that I've been doing in the past six years for this lecture.

00:10:18 So here we go.

00:10:39 Good evening hockey fans.

00:10:48 And this is a physiological effect, are we back? Which among other things makes people very dizzy if you inhale a lot of helium because of course you're replacing the oxygen that is so very important to my life with helium so I think we will do no more of that demonstration.

00:11:12 Now in talking about gases we talked about gaseous equilibrium systems and we talked about equilibrium and aqueous solution.

00:11:20 What I'd like to do now is demonstrate another favorite reaction that we have been doing in these lectures.

00:11:27 That is the reaction of carbon dioxide.

00:11:31 What I'd like to do is ask for two volunteers from the students to come and how about you?

00:11:39 Would you mind coming here?

00:11:42 What I'd like you to do is to hold this and just stand over here for a minute, just look over there.

00:11:48 And I'd like to get another volunteer, how about you?

00:11:52 And what I'd like you to do is to turn your back to him now so you don't see what you're doing.

00:11:58 And what I'm going to do is give you a liquid each, just a little bit, hopefully about the same amount.

00:12:06 No, don't drink it, no, no.

00:12:09 And you take a little bit too.

00:12:13 Now if you would hold these in such a way that your hand is not covering up the...

00:12:19 Yeah, right, just hold it like that.

00:12:21 Now I'm going to give you one of those straws and you take one of those straws too.

00:12:25 But I want to make sure that you do not inhale any of the liquid, don't suck any of it, okay?

00:12:30 I would like you to start blowing when I say go.

00:12:32 And blow very gently because otherwise the liquid will boil over the flask.

00:12:37 So whenever you're ready, you ready? Okay, go.

00:12:41 Very gently, okay.

00:12:49 He can take a breath in between, you see that?

00:12:51 Laughter

00:12:56 Now as you can see, maybe you can't see that too well.

00:13:03 What's actually happening is that they're exhaling the carbon dioxide.

00:13:06 And this carbon dioxide is reacting with the solution of calcium hydroxide that's in there.

00:13:13 And you see we're developing a very cloudy situation here, kind of vague.

00:13:18 And I think both of you have enough cloudiness now, so I think I'd call it a draw again.

00:13:23 And I thank you both for doing this.

00:13:26 Thank you very much.

00:13:28 Applause

00:13:33 All right, well let's go on and talk about a few more types of demonstrations involving chemical equilibrium.

00:13:45 What you see here is three flasks that contain nitrogen dioxide, which is a brown gas.

00:13:53 And the nitrogen dioxide is in equilibrium with another, with a dimer of NO2, which is N2O4.

00:14:00 And the effect on the position of equilibrium can be demonstrated by simply taking one of these flasks and putting it in ice water.

00:14:10 And then taking the third flask and putting it in hot water.

00:14:15 And the color, as I said, is due to the NO2 that is present.

00:14:20 And we can then observe the change in the position of equilibrium if it is affected by temperature

00:14:27 by simply watching the change in the intensity of the color.

00:14:31 Remember our reference point is the one in the middle here where the temperature is still room temperature.

00:14:36 And you see that the concentration of NO2 increases as you increase the temperature.

00:14:42 And the chemical representation, of course, for this is the equilibrium system.

00:14:47 And we can then relate the concentration, that is the effect of temperature now, on the position of equilibrium as well.

00:14:57 Now, in this lecture, we do a variety of demonstrations that I have done before and a variety of new demonstrations.

00:15:06 And we always involve a large number of people that help out in these demonstrations.

00:15:14 It is really very important for us...

00:15:19 Wow, it's Bucky again.

00:15:28 Welcome, Bucky. This is, again, a thank you.

00:15:31 May I take this from you? I don't think we're going to need it now for a while.

00:15:35 The football season is over, so let me put the safety pin here.

00:15:40 And I'd like you to stay for a while if you can. Can you?

00:15:46 Oh, great. Well, I've got a place for you here, so why don't you make yourself comfortable.

00:15:53 By golly, he fits in there.

00:15:56 Well, Bucky, I'm glad that you're here.

00:16:00 I'm sure that you enjoy these demonstrations. Otherwise, you wouldn't come back.

00:16:05 You're not registered in the course, are you?

00:16:09 You're not repeating it or anything like that.

00:16:12 You're just interested in what's happening. Well, that's good.

00:16:15 Well, I'd like to dedicate the rest of the demonstrations to you.

00:16:19 And I really thank you for taking the time out from your busy schedule to come.

00:16:25 I know final exams are coming up and you have lots to prepare for.

00:16:29 But I do hear that usually you spend a lot of time badgering the cheerleaders.

00:16:35 No? No? I'm sorry, Bucky. I didn't mean that.

00:16:39 No, no. Please stay. All right? Thank you. Thank you, Bucky.

00:16:43 Well, what I want to do, Bucky, is to show you how important it is to make observations when we're studying chemical systems.

00:16:56 And what I have here is a beaker with a very clear liquid in it,

00:17:01 which happens to be nitric acid, very concentrated nitric acid.

00:17:06 And I have this piece of copper, which I'm going to cut.

00:17:15 I'll cut another small piece and still another piece.

00:17:20 And you see freshly cut copper is quite shiny. You see the edge is quite shiny here.

00:17:25 And let's watch and see now what happens when I take this piece of copper and drop it into this concentrated nitric acid.

00:17:35 And you see there are various things happening. A gas is given off.

00:17:41 You see bubbles. The solution is changing color.

00:17:44 You see that the gas above the liquid is becoming brown in color.

00:17:52 And this gas that's brown in color is actually NO2, nitrogen dioxide.

00:17:56 The product of the reaction itself is nitric oxide, NO.

00:18:01 When NO, the pollutant, reacts with oxygen in the air, it becomes nitrogen dioxide.

00:18:07 And the NO2, of course, has this characteristic color.

00:18:13 And in doing this kind of thing, you see, Bucky, we can again demonstrate the importance of making observations.

00:18:20 You see the properties of the copper metal have changed as we have put them in the nitric acid.

00:18:27 The properties of nitric acids have changed.

00:18:29 So let me just add the contents of this beaker to this other beaker now that contains water by simply diluting it.

00:18:42 And you see by simple dilution, then, the color changes and, of course, the concentrations do change.

00:18:50 Now, I'd like to also do a few other demonstrations involving these indicators.

00:18:55 When we discussed the equilibrium phenomena involving acid-base indicators,

00:18:59 we said that indicators are weak acids or weak bases that have different colors in the ionized form and also in the unionized form.

00:19:08 And I've chosen here a set of indicators which I hope will change colors as I change the acidity of the solution.

00:19:16 And I'm going to change the acidity of the solution by simply allowing carbon dioxide from the form of dry ice to bubble and to react with the contents of these cylinders that you have here.

00:19:31 Notice, Bucky, that I'm putting a dry ice in every other cylinder so that you can remember,

00:19:38 in case you don't remember, the color that the cylinder had before I added the carbon dioxide.

00:19:43 And these cylinders contain, as I said, solutions with the indicators.

00:19:49 And as the carbon dioxide reacts with the contents of the cylinders, of course, the acidity of the solution changes.

00:19:57 And when the acidity of the solution changes, we can detect that by a change in the color of the indicator.

00:20:07 Let's just help things along a little bit here by adding more of this dry ice.

00:20:15 Again, remember, Bucky, that as we increase the concentration of one reagent, then the position of equilibrium shifts.

00:20:22 And there's one more going here, so let's see what happens to that one.

00:20:28 And you see this cylinder has already changed color.

00:20:30 It's already very light pink.

00:20:33 This cylinder now is taking on a different shade of yellow, although it's still yellow.

00:20:40 The blue indicator over here and the red indicator at the end are beginning to change color, but not very much.

00:20:48 So we'll let those go for a while and see what happens.

00:20:57 Well, the red one is beginning to change color, so is the blue one.

00:21:02 You can see that, Bucky, right?

00:21:04 And this one is colorless now.

00:21:06 Of course, we can bring the color back if we add a solution of a substance that is basic, that is alkaline.

00:21:13 Carbon dioxide solutions are usually slightly on the acid side.

00:21:18 There you see the orange color at the end, the change in the indicator.

00:21:25 Well, actually, Bucky, as you know, it is a bit warm in here, isn't it?

00:21:32 Do you feel kind of warm?

00:21:35 Maybe it's time that I take this sweater off because it is kind of warm in here.

00:21:42 So let me do that.

00:22:03 Well, I see that some of your friends, Bucky—

00:22:07 Remember now, they're your friends and my friends, but some of them agree with this and the others don't agree.

00:22:12 That's probably because the final exam is coming up and they all feel the pressure of exams.

00:22:19 And I agree with them.

00:22:21 Of course, it's very easy for me to get up and say this now.

00:22:25 And I hope a week from today, when exams are over and everybody is enjoying the holidays,

00:22:31 you'll be able to say the same thing that I'm saying now.

00:22:36 Now, one of the properties of liquid nitrogen, as I mentioned before, is that it is very, very cold.

00:22:47 And it has various properties on a variety of compounds.

00:22:51 Here's a rubber ball, a simple 19-cent rubber ball.

00:22:56 You want me to throw it to the students?

00:22:59 Okay, you ready?

00:23:01 All right, here we go.

00:23:23 Well, you can throw that back to me kind of gently.

00:23:27 Don't take very good aim.

00:23:30 You can't find it, huh?

00:23:32 Well, I'll tell you what, I have another one here.

00:23:37 Just in case the other one was thrown over, as so many of you were yelling, I have this other one here.

00:23:45 And what I'd like to do is, of course—gee whiz, I have two.

00:23:51 What I'd like to do is add some liquid nitrogen to this and see what happens to it.

00:23:58 You see it dances around as the liquid nitrogen evaporates, changes to the gaseous form.

00:24:05 And, of course, the temperature is very, very cold.

00:24:11 Pick it up. No, I'm not going to pick it up with my hands.

00:24:16 Let's try to pick it up now this way, see what happens.

00:24:21 Look what happened to it.

00:24:22 But many—oh boy, it's really cold.

00:24:27 There it is.

00:24:29 And it—

00:24:39 All right, all right, all right.

00:24:43 There's a lot of good stuff here, so let's see.

00:25:00 I'm prepared, you see.

00:25:03 Okay, let's just dip it in, make sure it's nice and cold.

00:25:16 There it is.

00:25:18 Let's see what you have as a shattering experience.

00:25:22 Aw.

00:25:26 It'll get better, it'll get better.

00:25:29 Maybe. Let's save some of this liquid nitrogen here.

00:25:35 Now, one other thing I'd like to show you is a chemical reaction that involves oxidation reduction.

00:25:45 What I have here is this piece of copper that is cut in the shape of a tree.

00:25:51 What I'm going to do is dip this into this large beaker that contains a solution of silver nitrate.

00:26:00 And, of course, very shortly you'll begin to notice a chemical change.

00:26:08 Now, how do we know that a chemical change is taking place?

00:26:11 Well, the properties of the system change.

00:26:13 The color changes.

00:26:15 The appearance of the solid copper changes.

00:26:19 You see it's getting quite dark now.

00:26:21 We'll let this chemical reaction take place that produces copper ions and solution and deposits silver on the tree.

00:26:30 Hopefully, in a short period of time, as we let this slow chemical reaction proceed,

00:26:35 we will see the formation of a very nice tree that is very commonly used around this time of the year.

00:26:44 Now, another thing that I'd like to do with the liquid nitrogen is to show you the rate at which it is evaporating.

00:26:54 Let's see. Which one is it?

00:26:56 So what I'm going to do is take some of this liquid nitrogen and put it in this tube.

00:27:03 There it is.

00:27:05 And put the squirt on it.

00:27:12 Oops.

00:27:14 We're supposed to have a liquid nitrogen can in here, but we had a dud.

00:27:18 So let's see what happens.

00:27:19 There we go.

00:27:24 Now, who was it that threw the ball at me?

00:27:26 Where is he?

00:27:32 Oh, I'm out of fuel. I'm out of fuel.

00:27:35 Hang on. Make sure that person stays where he is.

00:27:43 Ready? Aim. Fire one.

00:27:47 There you go.

00:27:55 Another dud. Is that what you think?

00:28:09 Bucky, a lot of things aren't working out too well. You know that.

00:28:16 There you go. OK.

00:28:18 OK. We'll save the rest of this nitrogen.

00:28:22 Well, another property of nitrogen that is very, very common, liquid nitrogen that is,

00:28:29 as well as gaseous nitrogen, is that it is not attracted between the poles of a magnet.

00:28:34 In other words, nitrogen itself is a diamagnetic substance in contrast to oxygen,

00:28:39 which is a paramagnetic substance.

00:28:42 And if I were to take some of the nitrogen and use this big magnet that I have here,

00:28:51 and if I were to pour some liquid nitrogen between the poles of the magnet,

00:28:57 for one thing, you see the magnet is very powerful.

00:29:00 It's attracting the doer itself, so I have to fight that.

00:29:03 But you see, as the nitrogen is poured between the poles, that it is not attracted to the poles.

00:29:12 Now, in contrast, let's see if we can contrast this to liquid oxygen.

00:29:18 First of all, liquid oxygen has this nice blue color.

00:29:23 And if we were to add the liquid oxygen,

00:29:32 you see the paramagnetism, which is a property of oxygen,

00:29:36 is exhibited very readily as the oxygen evaporates

00:29:41 and it disappears in between the poles of the magnet.

00:29:45 And oxygen in the liquid form has a very, very high concentration.

00:29:51 It's about 700 times the concentration of oxygen in the gaseous phase.

00:29:56 And, of course, what I like to do every now and then, like the rest of you,

00:30:01 is have a cocktail.

00:30:03 What I'd like to do right now is have a liquid oxygen cocktail.

00:30:09 And, of course, with the recent ban on smoking in public places,

00:30:15 it's not possible for us to smoke now in public places.

00:30:19 But with Mayor Soglin's permission and with the permission of the City Council,

00:30:23 for the purpose of this demonstration,

00:30:25 I'm going to enjoy my liquid oxygen cocktail and smoke a cigarette.

00:30:30 So, here we go.

00:30:33 Cheers.

00:30:47 Cheers, Bucky.

00:31:03 See, as I said, the concentration of liquid oxygen is so high

00:31:07 that it does support combustion much more readily than oxygen in the air.

00:31:13 And let me demonstrate this to you now by taking the cigarette

00:31:17 and pouring the liquid oxygen right on it.

00:31:22 Oh.

00:31:28 And you see that very few ashes are left.

00:31:32 It's a very efficient way of getting rid of cigarette ashes

00:31:37 and maybe cigarettes altogether.

00:31:45 Well, we've been talking about a variety of reactions that take place

00:31:50 in aqueous solution in the gaseous phase and liquid phase.

00:31:53 But I'd like to show you now, Bucky,

00:31:55 is a chemical reaction that takes place in the solid state.

00:31:59 And to do this, I'm going to move over to this side here

00:32:04 where you see I have this beaker with the orange solid in it.

00:32:10 And I've got this wire gauze on top of it, which I'm going to simply take.

00:32:15 And let's watch now and see what happens

00:32:18 as I try to catalyze the reaction by supplying it with some energy

00:32:27 in the form of this fire here that I have.

00:32:34 Let's see what's happening.

00:32:36 Remember that the color of the solid now is orange.

00:32:41 And the reaction is about ready to go.

00:32:44 There it goes.

00:32:45 Let me just cover this here

00:32:47 to make sure everything stays in place.

00:32:52 And what you see, beginning to see, I hope,

00:32:58 is the reaction going and going.

00:33:04 And it sure looks like a volcano as it proceeds.

00:33:10 In fact, quite often this reaction,

00:33:12 which is the decomposition of ammonium dichromate

00:33:15 as ignited by the matches I did, is referred to as a chemical volcano.

00:33:21 The reaction yields nitrogen as a product and chromium 3 oxide.

00:33:25 And as the nitrogen escapes, the chromium 3 oxide,

00:33:28 which is the product, is in this fluffy form.

00:33:31 And it's going and going and going.

00:33:35 And I hope it quits pretty soon.

00:33:38 Otherwise, it's going to be a mess to clean up this place

00:33:41 a little bit later on.

00:33:45 And so this reaction, then, is a reaction

00:33:48 that takes place in the solid state initially.

00:33:56 Now, what I'd like to do is take a look

00:33:59 at the copper in the silver nitrate solution.

00:34:03 And you can see now the beginning of the formation of what

00:34:07 I hope would look like a Christmas tree as the silver,

00:34:12 the shiny silver, deposits on the copper.

00:34:17 And the copper goes into solution.

00:34:19 The copper ion in solution has a characteristic blue color.

00:34:22 And it is a very faint color right now.

00:34:24 But as the reaction proceeds further, the color intensity will change.

00:34:31 Well, what I'd like to do now, Bucky, is go back to the aqueous phase

00:34:34 and do a series of demonstrations involving these beakers

00:34:41 that I have in front of me here.

00:34:43 And basically, what I'm going to do

00:34:45 is add one solution from one beaker to the other.

00:34:50 And then we'll see what happens.

00:34:53 But in order to keep track of what's happening,

00:34:55 I'm going to count.

00:34:57 And as I count now, we'll watch what happens.

00:35:01 So here we go.

00:35:02 1, 2, 3, 4, 5, 6, 7, 8, 9, 10.

00:35:07 1, 2, 3, 4, 5, 6, 7, 8, 9, 10.

00:35:14 1, 2, 3, 4, 5, 6, 7, 8, 9, 10.

00:35:23 1, 2, 3, 4, 5, 6, 7, 8, 9, 10.

00:35:27 See, something has already happened in the first one, Bucky.

00:35:31 1, 2, 3, 4, 5, 6, 7, 8, 9, 10.

00:35:37 1, 2, 3, 4, 5, 6, 7, 8, 9, 10.

00:35:44 Well, I want to make sure you're following.

00:35:46 There's another one that changed.

00:35:47 You see, Bucky?

00:35:48 Let's see.

00:35:49 1, 2, 3, 4, 5, 6, 7, 8, 9, 10.

00:35:52 I better hurry this up.

00:35:54 OK.

00:35:55 1, 2, 3, 4, 5, 6, 7, 8, 9, 10.

00:35:58 There it goes.

00:35:59 It should go on a count of 10.

00:36:00 Here we go again.

00:36:01 1, 2, 3, 4, 5, 6, 7, 8, 9, 10.

00:36:05 1, 2, 3, 4, 5, 6, 7, 8, 9, 10.

00:36:12 10 and a half, 11, 12, 13.

00:36:16 There's the orange one.

00:36:18 Let's go back to this one.

00:36:19 1, 2.

00:36:21 Let's see what happens to this one.

00:36:22 1, 2, 3, 4, 5, 6, 7, 8, 9, or 9 as the operators used to say,

00:36:33 10, 10.

00:36:37 There you go.

00:36:38 Well, what I'd like to do, Bucky,

00:36:44 is since you're really such a good sport,

00:36:46 I'd like you to try one of these demonstrations yourself.

00:36:49 And I'll ask for the chemicals now to come out.

00:36:51 So if Gary would bring the chemicals out,

00:36:54 and we'll get Bucky to help us out in these demonstrations.

00:36:59 Why don't you stay out there, Bucky?

00:37:01 Then everybody can see what you're doing,

00:37:03 because we want to make sure.

00:37:04 Thank you, Glenn.

00:37:06 OK?

00:37:07 I'll come around and help you out with this, Bucky.

00:37:10 Not that you need any help, Bucky.

00:37:12 But OK, what we're going to do, you take this beaker here.

00:37:16 No, you take this one here.

00:37:19 Boy, you sure have big paws there.

00:37:21 OK?

00:37:22 Take it this way, and you're going

00:37:24 to pour into this large beaker.

00:37:26 All right?

00:37:27 Is that too hard for you, Bucky?

00:37:28 Oh, OK.

00:37:29 And I'll do the same thing.

00:37:30 So whenever you're ready.

00:37:31 You ready?

00:37:32 OK.

00:37:35 And now let's see what happens.

00:37:37 We can count, if you like.

00:37:38 You know how to count, Bucky?

00:37:40 But you're not going to, huh?

00:37:42 I see.

00:37:43 OK.

00:37:44 I'll do it for you.

00:37:45 1, 2, 3, 4, 4.

00:37:47 Oh, yours went on four.

00:37:48 Mine is kind of slow.

00:37:50 5, 6, 7.

00:37:53 There we go.

00:37:54 There.

00:37:55 And there you see colors that are

00:37:57 very familiar to you, of course.

00:37:59 And these are the colors that should make you very happy.

00:38:02 So thank you, Bucky, for helping out with this.

00:38:04 I hope you don't have to go now.

00:38:09 Can you stay for a few more minutes?

00:38:11 OK, thanks.

00:38:12 OK, good.

00:38:13 What I'd like to do also, Bucky, is another demonstration

00:38:17 for you.

00:38:18 And by simply using this solution that I have.

00:38:35 And I add the solution from another beaker.

00:38:37 And I have now, I don't have to stir it up.

00:38:39 It just goes fast by itself because I

00:38:41 have the magnetic stirrer.

00:38:42 And I add this third solution.

00:38:44 And there you see color developing immediately.

00:38:47 Oops, there it goes, the color in the other direction.

00:38:50 And let's see if it's going to do anything else.

00:38:57 One of our balloons, one of our helium balloons,

00:39:00 finally gave up the ghost.

00:39:03 OK, and you see this is an oscillating type of reaction.

00:39:06 It has a certain period.

00:39:08 It changes color.

00:39:09 We know of the oscillation by, again,

00:39:11 observing the change in color.

00:39:14 Do you like those colors, Bucky?

00:39:16 You like them.

00:39:16 You probably would like the red and white colors better.

00:39:19 How about if I tried to work on a demonstration for next year

00:39:22 that involves a red and white color change, all right?

00:39:25 OK, it's a deal then.

00:39:26 All right, now we'll have this reaction going for a while.

00:39:32 And what I'd like to do is show you

00:39:37 another type of chemical reaction

00:39:39 that gives off energy in the form of light.

00:39:43 And I'm going to use this spiraling tube.

00:39:52 And as we get ready here, I have these two solutions.

00:39:59 And what I'm going to do is pour these two solutions down.

00:40:10 OK, let's do it again.

00:40:11 There you go.

00:40:18 And you see this reaction is called chemiluminescence

00:40:22 because it gives off energy in the form of light

00:40:26 rather than the form of heat.

00:40:31 Let's do it one more time.

00:40:35 OK, there you go.

00:40:38 And could you see that, Bucky?

00:40:42 All right, maybe if I turned off the lights a little more,

00:40:44 then you'd see better.

00:40:47 OK, let me do a similar type of reaction, Bucky,

00:40:53 which involves chemiluminescence.

00:40:55 But before I do that, I want to show you

00:40:58 the formula for the chemical reaction that

00:41:01 just took place here.

00:41:03 And the formula for this reaction

00:41:05 is one that involves an organic compound.

00:41:08 And the organic compound is called,

00:41:10 it has a trivial name, it's called luminol.

00:41:13 And this is actually called the luminol reaction.

00:41:16 What happens when I mix the two liquids together

00:41:18 is that an oxidation reaction took place

00:41:21 in an alkaline solution and produced the compound

00:41:25 whose formula you see on the lower right-hand side.

00:41:28 And this compound is in an excited state.

00:41:31 And when it goes to its so-called ground state,

00:41:34 it gives off energy in the form of light.

00:41:36 And that is the light that you saw.

00:41:39 And what I have here is simply another form

00:41:41 of this same type of reaction.

00:41:44 It's not quite the same chemicals.

00:41:46 But this, you see, is a commercially available

00:41:50 so-called cool light.

00:41:53 And maybe if I dim the lights here,

00:41:56 maybe we'll see things a little bit better.

00:41:59 OK.

00:42:00 And I want you to watch this very carefully, Bucky.

00:42:02 So here we go.

00:42:04 And you see, when I break this inner tube that contains,

00:42:07 in this case, hydrogen peroxide, I mix the two liquids together.

00:42:10 And they're inside this plastic container here.

00:42:13 And it's quite safe to handle.

00:42:14 You see what I'll do now.

00:42:15 I'll just throw it to the people out there.

00:42:17 And, uh.

00:42:19 OK.

00:42:20 And here's another one, which I'll throw to the people

00:42:24 this side here.

00:42:25 There we go.

00:42:34 And, Bucky, you're such a good sport.

00:42:37 I'm going to give you a little present.

00:42:39 And I'm going to give you a little present.

00:42:41 And I'm going to give you a little present.

00:42:43 And I'm going to give you a little present.

00:42:45 And, Bucky, you're such a good sport.

00:42:48 I'm going to give you one yourself, which you can break

00:42:51 later on if you want to.

00:42:54 But you can also save it if you like.

00:42:56 So you can have that as a present.

00:43:05 Now, what you see here, Bucky, you've

00:43:08 been noticing this green flame, you see.

00:43:11 And it is in keeping with the Christmas season

00:43:14 that we have here.

00:43:15 And I'm going to add a little more color to it

00:43:19 by heating up this wire and by then dipping it

00:43:23 into this salad.

00:43:24 And let's see what happens.

00:43:26 And there you see you get the two Christmas colors.

00:43:29 Let's do it one more time.

00:43:32 There you go.

00:43:33 You see the color changes one more time.

00:43:39 Now, quite often, when one is doing demonstrations

00:43:41 of this type or watching the hockey game

00:43:44 or watching the football game, you get thirsty.

00:43:46 And you try to go for something that will cool you down

00:43:51 and have something cold to drink.

00:43:53 And basically, what you go after is a pop bottle, right?

00:43:58 And what you do then is drink.

00:44:01 There you go.

00:44:03 Now you know why they call it the pop bottle, Bucky, right?

00:44:07 No, you don't like that, Bucky.

00:44:10 I'll tell you what, Bucky.

00:44:11 I'll try to make things up for you

00:44:13 by reading this poem that is a tradition in this lecture.

00:44:18 This poem has been written by a variety of people.

00:44:23 It has some good lines in it and has some bad lines in it.

00:44:26 I'm responsible for the good lines.

00:44:28 And the other people, of course, are

00:44:30 responsible for the bad lines.

00:44:33 It goes something like this.

00:44:36 Once upon a Christmas dreary, in the lab of Shakashiri.

00:44:41 No?

00:44:44 Christmas, you say, and in the lab,

00:44:47 most would find it sad and drab.

00:44:50 But not in the lab of Shakashiri,

00:44:53 where everything is bright and cheery.

00:44:57 I told you it's got some good lines and some bad lines.

00:45:00 I told you it's got some good lines and some bad lines.

00:45:03 Flasks, round bottom, and Erlenmeyer,

00:45:07 full of earth, air, water, and fire.

00:45:11 The place had a stinking smell

00:45:14 that made one feel not too well.

00:45:18 When suddenly there was a knock,

00:45:21 Shiri stood in a state of shock.

00:45:24 Out from the hood jumped Santa Claus,

00:45:27 holding 103 books in his paws.

00:45:30 He caught me working and chewing gum,

00:45:33 and he wondered about my equilibrium.

00:45:36 I became very irate when he dissolved my precipitate,

00:45:39 and he said,

00:45:42 I don't know what you're talking about.

00:45:45 I said,

00:45:48 I don't know what you're talking about.

00:45:51 I became very irate when he dissolved my precipitate.

00:45:58 Santa started to sway his hips

00:46:01 when he found out about chem tips.

00:46:04 Then he shrieked,

00:46:07 from my helper-keeper breast,

00:46:10 she's not taking her hourly test.

00:46:13 Keep your hands off my sweet blonde.

00:46:16 I know about your covalent bond.

00:46:22 He was being completely unfair.

00:46:25 As a Lewis acid,

00:46:28 all I wanted was a pair.

00:46:39 Santa, while he could,

00:46:42 started leaving through the hood.

00:46:45 He disappeared with fan and fare

00:46:48 and Shakashiri standing there

00:46:51 saw an end point in the air.

00:46:54 How's that, Bucky?

00:46:57 Like that?

00:47:06 Well, what I'd like to do now

00:47:09 is do another dramatic demonstration for you,

00:47:12 and I'm going to ask for some help in doing this.

00:47:15 I've received a lot of help in these lecture demonstrations,

00:47:18 not only today,

00:47:21 but in all the lecture demonstrations that I do

00:47:24 and other professors in chemistry do,

00:47:27 and we receive very excellent help

00:47:30 from the lecture demonstrators that we have,

00:47:33 and I'd like to call one of them now,

00:47:36 Bill Weber, to come and help out

00:47:39 in one of the demonstrations.

00:47:43 Okay, Bucky, I want you to pay very close attention

00:47:46 because this is a very slow type of reaction.

00:47:49 It will not take place very fast.

00:47:52 It's not very noisy at all,

00:47:55 so pay attention, and let's go.

00:47:58 Here we go.

00:48:01 Did you see that, Bucky?

00:48:04 Did you see that?

00:48:07 Well, unfortunately, we don't have the facilities

00:48:10 to do that again.

00:48:13 On commercial television, we have instant replay.

00:48:16 You can see somebody drop a pass from five different angles,

00:48:19 but in educational television,

00:48:22 we don't have that capability yet,

00:48:25 and hopefully next year when you come to visit again,

00:48:28 we will have the capability of the instant replay

00:48:31 and the playback and the slow motion,

00:48:34 and we can show you that type of demonstration again,

00:48:37 as the reaction proceeds.

00:48:40 Well, in keeping with the Christmas spirit

00:48:43 and in keeping with the types of demonstrations

00:48:46 that we are doing,

00:48:49 I would like to again invite Bill Weber

00:48:52 and Vince Jenner to come and do a demonstration for us

00:48:55 where they are going to try

00:48:58 to prepare some Christmas ornaments.

00:49:01 What they have, you see these round bottom flasks,

00:49:04 and they have these liquids in them,

00:49:07 and what they're doing is shaking the liquids,

00:49:10 and of course you can see that they are pretty jolly.

00:49:16 And you can also see that the flasks that they are swirling

00:49:19 are getting shinier and shinier,

00:49:22 and this shininess is due to a thin layer of silver

00:49:25 that is depositing due to a chemical reaction

00:49:28 that is taking place inside the flask.

00:49:35 Maybe next year we'll bring in the university band here, fellas,

00:49:38 and you can...

00:49:41 What you see now, the chemical reaction,

00:49:44 which is an oxidation-reduction reaction,

00:49:47 results in the formation of this very shiny precipitate.

00:49:59 And what they're going to do now

00:50:02 is take these large Christmas ornaments

00:50:05 and hang them on the Christmas tree

00:50:08 that they said they are putting together for us,

00:50:11 and of course they will make very nice, shiny ornaments.

00:50:14 So thank you very much, fellas.

00:50:20 And now what I'd like to do

00:50:23 is also call on a person who has devoted a lifetime

00:50:26 to doing lecture demonstrations,

00:50:29 and he has retired from this department,

00:50:32 but he, having heard that you are making a visit

00:50:35 to our special lecture, Bucky,

00:50:38 has agreed to come out of retirement

00:50:41 and do a fantastic demonstration.

00:50:44 So I'd like to call Talley, then,

00:50:47 to come out and do his demonstration.

00:50:50 Here's Talley.

00:50:54 I'd like to do, perhaps,

00:50:57 the most dramatic demonstration you've seen all year,

00:51:00 with apologies to Dr. Shakashiri.

00:51:03 This demonstration was worked out

00:51:06 by Professor Sorum, who used to be on the staff,

00:51:09 and it was perfected by me,

00:51:12 who used to be on the staff.

00:51:15 As you know, this is the Christmas season,

00:51:18 and this is called the Christmas demonstration.

00:51:21 Christmas is always a time of bright colors,

00:51:27 and a chemistry lab is a place to produce bright colors.

00:51:32 All we do is add a couple things together,

00:51:35 and sometimes we get brilliant colors.

00:51:40 Well, I could go on doing more of these,

00:51:45 but maybe something else can be done here.

00:51:51 BELL RINGS

00:52:10 APPLAUSE

00:52:21 Thank you very much, Talley.

00:52:30 There he is again.

00:52:33 Thank you, Talley.

00:52:36 I'm glad you had time to come out and join us again.

00:52:39 I'd like to try to do another demonstration

00:52:42 to see if I can come close

00:52:45 to the one that Talley just did here.

00:52:48 I've got two liquids, you see.

00:52:51 Maybe the thing to do is for me

00:52:54 to get this glorious Christmas tree out of the way here

00:52:57 so we can see better what's happening.

00:53:00 I've got these two liquids, you see, and I've got them together.

00:53:03 What I'm going to do is simply pour them in this large beaker.

00:53:12 They're quite syrupy, you see.

00:53:15 I kind of mix them together like this.

00:53:21 For chemical reactions to take place,

00:53:24 you have to mix the reactants quite well.

00:53:27 That's what I'm trying to do here.

00:53:34 One thing we see happening is, of course,

00:53:37 there's a color change.

00:53:46 Many times when we try to do demonstrations,

00:53:49 well, not many times, a lot of times,

00:53:52 we try them out and

00:53:55 you see something is beginning to happen here.

00:54:00 This thing, my gosh, it's growing.

00:54:10 See, I have this great magnet here that's attracting it.

00:54:14 It's coming up. You don't believe that, do you?

00:54:19 Let's see what's happening to this thing here as it grows.

00:54:27 Oh, come on, stay in there.

00:54:36 You better help this thing along a little bit.

00:54:39 Just straighten it out.

00:54:43 Stay in there.

00:54:46 Stay in there.

00:54:58 Well, Bucky, we tried anyway.

00:55:01 This is an example of a polymer, actually.

00:55:04 It's polyurethane and it is one of the chemicals

00:55:07 that we will be talking about next semester in Chemistry 104.

00:55:10 Bucky, you have been a good sport

00:55:13 and I would like to give you a present before you go.

00:55:16 It is actually in the form of this polymer here.

00:55:19 You see it's the same type of polymer

00:55:22 and it's a very tasty orange freeze

00:55:25 which I'd like you to take.

00:55:28 I thank you for coming and I really appreciate your being here.

00:55:31 Thank you very much, Bucky, and we'll see you next year.

00:55:40 I'd like to show you another example

00:55:43 of the properties of polymers by looking

00:55:46 at an ordinary piece of plastic.

00:55:49 What I have here is two crossed polarizers.

00:55:52 They're not crossed yet,

00:55:55 but they are two pieces of polarized film.

00:55:58 These pieces of polarized film

00:56:01 have very interesting properties.

00:56:04 For example, we look at the properties

00:56:08 of a polymer in between the crossed polarizers.

00:56:11 First of all, you see what happens

00:56:14 when the polarizers are parallel to each other.

00:56:17 The two polarized film are parallel to each other.

00:56:20 The light comes through, but when they are in this position,

00:56:23 they are at 90 degrees to each other.

00:56:26 They are in the position of extension, as it's called.

00:56:29 If I were to take a piece of polymer film

00:56:32 and drop it in between the crossed polarizers,

00:56:36 the film of plastic has the property

00:56:39 of allowing light to come through.

00:56:42 This phenomenon is called birefringence.

00:56:45 It is another phenomenon that we will talk about

00:56:48 in Chemistry 104.

00:56:51 There is another more colorful display.

00:56:54 What I'm going to do now is take this polarized film

00:56:57 and I'm going to stretch it between the crossed polarizers

00:57:00 and let you watch and see what happens.

00:57:06 You see the colors that develop there

00:57:09 are, as I stretch this,

00:57:12 are interference colors.

00:57:15 These colors are due to the change

00:57:18 in the thickness of the polaroid

00:57:21 of the film of plastic.

00:57:24 I have another piece of plastic in here

00:57:27 which I'd like to show you very briefly.

00:57:30 It has some strain in it.

00:57:34 As we rotate this, you get these nice colors

00:57:37 that are due to the strain

00:57:40 that is in the polaroid

00:57:43 that is due to the strain

00:57:46 in the film of polymer.

00:57:49 This is another property

00:57:52 of very common chemical substances

00:57:55 that we will deal with in Chemistry 104.

00:57:58 I'd like to close this lecture

00:58:02 by thanking all of you for being here

00:58:05 and, of course, thanking the various people

00:58:08 who have helped make the course a success,

00:58:11 the teaching assistants and you, the students,

00:58:14 and all the supporting staff.

00:58:17 I want to thank the television crew from WHA

00:58:20 for all the efforts that they have put into making this lecture a success

00:58:23 and for bringing it to you.

00:58:26 I hope that I will see you again next year.

00:58:29 §§

00:58:59 §§