00:00:00 This was recorded using a Blu-Ray disc and recording software with a Nestle HD camera at home.

00:00:11 This is a video of a group of children at the Slate Hall in Macon, Minnesota.

00:00:22 Boys and girls, children of all ages, presenting the 20th Anniversary Annual

00:00:29 Holiday Lecture, University of Wisconsin Chemistry Professor Basam Shakhashiri.

00:00:52 Thank you and good evening everyone and welcome to my lab. I promise you a very

00:00:58 good time tonight. I want you to be as attentive as possible. It's so nice to

00:01:04 see so many old friends and to make some new friends tonight. These are very

00:01:08 special days for all of us because it is the holiday season and because all of us

00:01:14 are eager to learn about different things that surround us. We're all

00:01:19 curious about the world that we live in and we're going to do a number of

00:01:23 scientific experiments tonight. I hope you will find them enjoyable and

00:01:29 rewarding. I want you to know that this is the 20th anniversary of this special

00:01:35 lecture. I'm so proud to have had the opportunity and the privilege to be a

00:01:41 faculty member at the University of Wisconsin-Madison for that length of

00:01:45 time. I want you also to sit back and relax and enjoy what's about to happen.

00:01:53 I want all of you to pay special attention for color changes, be on the

00:01:58 lookout for smoke that might come out, and maybe an explosion or two that might

00:02:04 happen. As we do experiments, we want to be obeying all the safety regulations

00:02:10 and you will see that I will put my eye goggles, eye protection on, the safety

00:02:16 goggles, to protect my eyes from possible splashes that might take place. I also

00:02:21 want you to see that we have a fire extinguisher available just in case

00:02:26 something does go out of control. We're not planning on anything going out of

00:02:31 control, but we have to be very careful as we do the experiments tonight. Now,

00:02:40 why do experiments in chemistry? Why be concerned about chemicals? Because

00:02:45 chemicals are all around us. The food that we eat is made up of chemicals. The

00:02:51 air that we breathe is a mixture of chemicals. The clothes that we wear are

00:02:56 made up of chemicals. Our own bodies are made up of chemicals. What goes on inside

00:03:01 our bodies is nothing but a series of biochemical reactions. The medicine that

00:03:08 we take when we are ill is nothing but chemicals. The drugs that some of you

00:03:14 foolishly experiment with are also chemicals, and that's why we need to be

00:03:19 concerned about the properties of all chemicals, their benefits, their potential

00:03:26 hazards, and of course we need to be handling them in a very safe manner.

00:03:31 And that's why we want to now go through a series of experiments that show us

00:03:38 that we are having a lot of fun. You know, my button says here, science is fun. Fun

00:03:45 in the best sense of the word, and that's what I would like you to have with me

00:03:50 tonight. Also, when you go back home and do some of the experiments that you might

00:03:56 be able to perform at home, to have fun and to be challenged and to be

00:04:00 enjoying the festivities that are about to take place. Now, because I'm going to

00:04:05 do a lot of different experiments, it would be easier for me if I took my

00:04:10 jacket off. Would that be alright if I took my jacket off? That be alright? Okay, so

00:04:13 let me do that then, and I'll put my jacket over here. How about if I took my

00:04:23 tie off too? That be alright? Alright, it makes life easier for me if I take my

00:04:30 tie and loosen my collar a little bit. We can put this away here. How about if I

00:04:37 take my shirt off? Will that be alright? Okay, let's let's try that.

00:04:43 And I want you to see that I really believe that science is fun, and that's

00:05:03 why I'm wearing this t-shirt that gives that message too. So, I'll get the

00:05:07 microphone back up here, and we'll start the experiment by doing a simple

00:05:14 reaction we call a combustion reaction. We take a match and we strike it. Lots of

00:05:19 exciting and interesting things happen here. For one thing, this reaction

00:05:24 releases energy in the form of light, that's what we see, but also releases

00:05:28 energy in the form of heat, because you know, if I don't blow this out right now

00:05:33 I'll burn my fingers. How do you know that? You know that from experience, and

00:05:37 that's a key word I want you to be thinking about and using. Use the

00:05:41 experience that you have to learn more about the chemical world that we live in.

00:05:49 So that is one experiment that we will do, and I want to now show you a very

00:05:54 special experiment. I'm going to take a dollar bill, and I'm going to strike a

00:06:01 match, and very quickly burn this dollar bill. Did you see that, or was that too

00:06:10 fast? See, what we do in science, we try to repeat the experiment to make sure

00:06:16 that the observations are valid, and so what we have here is what looks like a

00:06:22 dollar bill. It's not a real dollar bill. This is made of special paper. This paper

00:06:28 is treated chemically so that when it burns, it does not leave a residue, and

00:06:34 that's what I'm going to try to show you again. Take this, and watch what happens.

00:06:45 There it goes. Okay, so if you know, if you know chemistry, if you know science, you

00:06:52 can do a whole bunch of different experiments, and that's one other

00:06:56 experiment I'm going to try to do now. I'm going to take a $20 bill. After all,

00:07:00 this is the 20th anniversary, right? Take this $20 bill, put it in this empty

00:07:05 beaker like so, and add a liquid to it just to soak it up, and what we'll do

00:07:17 next, take this $20 bill, soak it real well in this liquid. What does this

00:07:24 liquid look like? It looks like water, but actually it's not water. It is a

00:07:30 mixture of two liquids. One of them is water, so what we'll do next is take the

00:07:38 match, strike it, and see if we can burn this $20 bill, and you see, you saw the

00:07:53 flame, but the $20 bill is still intact. That's because this mixture is made up

00:08:00 of water. As you know, water does not burn. In fact, you use water to put out fires,

00:08:05 but also another chemical. Its name is isopropyl alcohol, and this mixture

00:08:12 causes the effect that we saw to happen. The alcohol burns, but the water does not

00:08:19 burn, and so this $20 bill is still good. I'll put it back in my wallet, and I will

00:08:27 use it to get some Christmas presents. All right, so that's one example for us

00:08:33 in terms of combustion. There are substances that burn and other

00:08:37 substances that do not burn. Those substances that burn are called

00:08:41 combustible substances, and what we're going to do now is try to use this big

00:08:47 torch that's connected to a fuel called methane. We're going to try to strike a

00:08:54 match and see. There. This is an example of a controlled combustion reaction. This

00:09:04 gas that's burning is called methane. It's natural gas. It's used as a fuel to

00:09:11 provide us with heat. It's used to heat this building, to heat our schools, to

00:09:15 heat our homes. That's because the combustion of methane is an exothermic

00:09:21 reaction. That's the reaction that releases heat, that releases energy in

00:09:26 the form of heat. It also releases energy in the form of light, as you see the

00:09:30 flame. If you look very closely, you see that the flame is mostly yellow, but has

00:09:35 a blue tinge near the tip of the burner, and one of the things that we study in

00:09:40 science is to try to understand why different flames have different shapes

00:09:44 and different colors. Well, when you came into the auditorium this evening, you

00:09:51 noticed a whole set of different things on the lecture table, and also you saw

00:09:55 these balloons. And I want to ask you, what do you think we have in those

00:09:59 balloons? Helium, you're saying. Some of you are saying helium. Well, let's set

00:10:05 this aside for a moment and ask you, why are you saying helium? Remember what I

00:10:10 asked you to think about before? I asked you to use the word experience. You are

00:10:15 saying helium because you know from experience that helium-filled balloons

00:10:20 are lighter than air, and they must be kept on a string. Otherwise, they'll go up

00:10:25 to the top of the room, or if you're outdoors, they'll just go up in the

00:10:31 air. So, the other thing we want to talk about and deal with tonight is that

00:10:35 helium itself does not burn. It's a non-combustible gas. So, one way in which

00:10:41 we can find out what is in those balloons is to take this flame and try

00:10:47 to see if the balloons burn. All right, so we'll take this flame and put it to this

00:10:54 balloon. And what happens? The balloon pops, right? The balloon pops, and I can tell you

00:11:02 that that balloon, the green-filled balloon, had helium in it, and helium is

00:11:08 a non-combustible gas. So, we go to the next one over here, and we'll see if this

00:11:14 one has helium in it or not.

00:11:18 Now, that

00:11:23 that balloon, that balloon exploded when we put the torch to it. That balloon was

00:11:31 filled with hydrogen gas, and hydrogen gas combines with the oxygen that's in

00:11:37 the atmosphere in a very explosive manner, as you saw. So, what we're going to

00:11:42 do next is repeat this same experiment with a second yellow balloon, but do it

00:11:47 in the dark and see if we can make some additional observations about the color

00:11:53 and the shape of the flame. You ready? Here we go.

00:12:01 Now with the lights on, I'm sure you noticed that the flame itself was big

00:12:08 and had a special color to it, and there was also sound energy released in that

00:12:17 explosive reaction. What we'd like to do now is to show you this last experiment

00:12:22 in slow motion. So, all you have to do is watch the monitor, and you will see the

00:12:26 experiment again. You won't hear any sound. There's the flame coming to the

00:12:30 balloon, and pretty soon you'll see a big ball of fire. See, that tells us

00:12:37 then if we study that, we can study the behavior of that explosive reaction and

00:12:42 learn something about combustion processes, especially the combustion of

00:12:46 hydrogen. Now, you being very good observers and making sense out of what

00:12:53 we're doing here, you notice that when we went from the green balloon to the

00:12:57 yellow balloon, the amount of sound energy increased, right? Got to be higher.

00:13:03 So as we go to the red balloons, you might guess, you might guess that there

00:13:09 may be more sound energy. You might guess there may be the same or even less, but

00:13:14 remember we said we want to be obeying the safety regulations, and therefore we

00:13:20 should be protecting our eardrums from potential damage. And the way to do that

00:13:25 is for you to take both fingers like so, and put them in your ears, okay? Now, if I

00:13:33 were to do that, I can't do the experiment, so what I have brought along

00:13:37 with me are some earplugs, and I will put the earplugs, and you put your, put your

00:13:48 fingers very, very strongly in there. If you can hear what I'm saying, that means

00:13:54 you don't have your ears plugged in safely. I can't hear you, but I can see

00:13:58 you laughing, so make sure that you have your ears protected, and we'll do this

00:14:03 and see what happens.

00:14:06 Now, that, that balloon had in it a mixture of hydrogen and oxygen, so the

00:14:27 oxygen was in immediate contact with the hydrogen, and that's why the amount of

00:14:33 sound energy was much, much higher than before. Let's repeat that experiment in

00:14:38 the dark now, okay? So put your ear, plug your ears very well.

00:15:03 You notice, you notice that the, that the shape of the flame and the color of the

00:15:13 flame is different, right? In fact, what we should do now is take a look in slow

00:15:18 motion at this last explosion. Again, you won't hear any sound, you'll just see the

00:15:23 ball of fire. There comes the flame, and very soon, there you go.

00:15:32 Well, that is an example of a combustion reaction that goes out of control, and

00:15:40 that's why we need to keep flames in any source of ignition away from hydrogen

00:15:46 and from mixtures of hydrogen and oxygen. So what we're going to do next now is

00:15:52 try another experiment in these plastic bottles that have two nails stuck on the

00:16:00 side, and they are separated on the inside by a distance of about one

00:16:05 centimeter. You know, in science we use the metric system, not the British system,

00:16:11 for measurements, and so the distance is in centimeters, and there's a cork at the

00:16:16 top, and then there's a small amount of liquid at the bottom. And what we're

00:16:20 going to do is use this sparker. I'll show you there's a big spark coming out

00:16:25 of this. I hold this very tightly. There, you see the spark? Okay, we'll try to spark this

00:16:30 and see what happens. That is another example of an uncontrolled combustion

00:16:40 reaction. The liquid that's at the bottom of the bottle is ethyl alcohol, and the

00:16:46 vapor from the ethyl alcohol is ignited when the spark jumps between one nail

00:16:52 and the other nail. So we have a whole bunch of these, and let's try to do them.

00:16:58 All right, you're ready? Okay, we'll do another one, like so. There you go. You

00:17:08 see what happens, that chemical energy, chemical energy changes into mechanical

00:17:14 energy, and the cork is ejected. All right, here's one more. There you go. You notice,

00:17:24 you notice again that the sound energy that's released depends on the size of

00:17:31 the container. Let's try this next one in the dark and see what happens when we

00:17:35 try it in the dark. You ready? Okay, now I can't see what we're doing. Let's try it. Here we go.

00:17:58 Okay, now I want you to know also that as I touch these bottles that they feel warm. Not this one,

00:18:04 nothing happened with this one. Oh, I can tell you why nothing happened here, because the two

00:18:07 nails are touching, so we need to separate the nails. But you've had enough of these

00:18:12 explosive reactions, right? All right, so let's move on to something different and something

00:18:19 that relates to combustion. If you take a balloon, you know I like balloons, and you blow the balloon

00:18:29 up like so, then you can tie it, and because it's filled with air, right, it's not going to ride,

00:18:35 it's going to sit like so. Now if you take a match and you strike this match, right, and you hold the

00:18:43 balloon up like so, and you put the match, oops, the balloon pops, right? You know that. Now here's

00:18:49 an experiment that you could try doing at home. You take a balloon and you put in it some water

00:18:57 before you blow up the balloon. Fill it up with water, okay, and then, and I have a small funnel

00:19:06 here just to help you get the water in, but it makes it more difficult to get the balloon off

00:19:12 the funnel now. All right, and the next thing that you do, whoops, is you blow about this size, you tie

00:19:24 it off, and you have this water in the balloon, right? So you put this off like so, you get a match,

00:19:38 and very carefully, you put the match right where the water is, whoops, I held it too long, I held

00:19:51 it too long. If you, if you do this carefully and don't hold the match too long close to the balloon,

00:20:00 the balloon will not pop. Now you try this experiment at home. Make sure, make sure when

00:20:08 you try this experiment, if you do it with an adult, because anytime you play with matches or

00:20:14 with fire, it is a very dangerous situation, potentially very dangerous, and that's why you

00:20:20 need to be very, very careful about it and do it with an adult. Now let's move on and talk about

00:20:29 and do experiments with one of the products of the combustion reaction, especially if, not

00:20:36 especially, only if the material that's burning contains carbon. Carbon-containing materials

00:20:42 produce, in a combustion reaction, produce carbon dioxide, and what we're going to do next is do a

00:20:49 whole bunch of experiments with carbon dioxide, which is at room temperature and pressure, a gas.

00:20:56 Except that, in this case, we're going to use carbon dioxide not in the gaseous form, but in the form

00:21:06 of a solid, and what I have here is chunks of dry ice. These chunks of dry ice are solid carbon

00:21:15 dioxide, and solid carbon dioxide is at a temperature of minus 78 degrees Celsius. Again, we use the

00:21:23 Celsius scale when we measure temperatures in science. This solid carbon dioxide does not change

00:21:31 from a solid to a liquid to a gas. It changes directly from being a solid to being a gas. That

00:21:37 process we call sublimation. So it's at minus 78 degrees Celsius, and it sublimes. It goes up

00:21:44 directly from being a solid into a gas, and so unlike ordinary ice, if you put ordinary ice in

00:21:51 a glass, what happens? It melts, right? And then after it melts, it disappears because it changes

00:21:57 into water vapor. This carbon dioxide in the solid form does not change into a liquid. It goes

00:22:04 directly into being a gas, and what we're going to do next is carry out a whole bunch of experiments

00:22:11 with carbon dioxide in the solid form to tell you for sure that if you take carbon dioxide and you

00:22:17 put it in water, you get carbonated water. In fact, all carbonated beverages have in them carbon

00:22:25 dioxide gas that has dissolved. So what we're going to do now is take chunks of carbon dioxide, of dry

00:22:32 ice that is, and we're going to do a whole bunch of experiments with these tall glass cylinders that

00:22:39 are arranged in a very special order. See, we have a pair of one color, another pair of a different

00:22:45 color, a third pair of still a different color, and a fourth pair of a color that's very close to the

00:22:51 color of the first pair. What we're going to do is take chunks of dry ice and drop them into this

00:22:57 cylinder, and into this one, and we see what happens. Lots of interesting things begin to

00:23:07 happen. Put a little more, a little more here, and you see bubbles. That's the carbon dioxide bubbling,

00:23:17 and you see some color changes taking place. Remember I told you to be on the lookout for

00:23:23 color changes, and I also told you to be on the lookout for a lot of interesting things that might

00:23:28 be happening. You see this white stuff coming off the top here? What do you, what do you think this

00:23:34 white stuff is? What does it look like? No, it's not carbon dioxide. Carbon dioxide is an invisible gas.

00:23:41 You can't see carbon dioxide. What does it really look like? It looks, water vapor? No, water vapor is

00:23:48 also an invisible gas. It looks like fog, as someone said. You know what fog is? It's condensed

00:23:54 water vapor, and the condensation is taking place on the carbon dioxide that's escaping. So we can

00:24:02 look at this. Isn't that interesting here? Now one of the things that we do in science is pay close

00:24:12 attention to all kinds of changes, including color changes, including the release of the gas, and the

00:24:20 condensation of water vapor in this case. Now these are all at room temperature, and what I want to

00:24:26 show you next is an experiment where I will take an empty dish pan like this, put it over here, and

00:24:32 I will put in it some hot water, some boiling water, and then we'll put some dry ice in that

00:24:38 and see what happens. So I'm looking for the hot water. I need a flask of hot water. I guess it's

00:24:44 not here. Can someone bring it out to me? Oh, come on over. Thank you, Bucky, and welcome.

00:24:52 Welcome, Bucky. Bucky is a very special chemistry student. He's been taking chemistry every year,

00:25:08 ever since I've been here, and he actually likes chemistry. Don't you like it, Bucky? Yeah, good,

00:25:17 good. I want to thank you for being here tonight, Bucky, and for helping out with this special

00:25:23 20th anniversary of this presentation. I'm very, very happy that you're here, and I want to do the

00:25:33 experiment that I talked about here. So, Bucky, if you would watch as we put the water in this

00:25:38 dish pan. What do you see coming off the top here? No, steam is an invisible gas. You can't see

00:25:46 steam. What do you see? No, water vapor is invisible, too. What is it? Condensed water vapor.

00:25:53 That's what it is, okay. Bucky, you got that, right? So let's take some dry ice and put it into this.

00:26:00 Now what does it look like? And you see that it is moving in a downward direction. That's because

00:26:19 carbon dioxide is heavier than air, and the condensation is taking place on the carbon

00:26:25 dioxide. You see that, Bucky? Now, initially, at the beginning of this experiment, the fog went

00:26:33 upward. So you want to think about that. How come initially it went upward, and now it's going

00:26:39 downward? Remember that this was hot, boiling water. So that's a little hint for those of you

00:26:46 who want to think about it. Now, Bucky, I know you're getting ready for final exams, and you

00:26:51 probably want to study, but I wonder if you can stay for the rest of this set of experiments. Can

00:26:56 you? Do you want Bucky to stay? If you have a seat right here, you can watch all the experiments

00:27:09 and see. Are you comfortable, Bucky? Great, all right. All right, so let's move on and look.

00:27:24 Did you bump your head, Bucky? Beauty, any first aid? You're all set. Okay, great, all right. Let's

00:27:32 move on and do a couple of other experiments that deal with carbon dioxide and show you one

00:27:42 of the experiments that involves a candle before we get to the carbon dioxide. You know, the great

00:27:50 British scientist Michael Faraday started the tradition of the Christmas lecture by talking

00:27:57 and demonstrating the chemistry of the candle. Now, you ever wonder why the candle stays lit?

00:28:04 Why does the candle stay lit? You think about that and think about the flow of the fuel,

00:28:09 which in this case is wax, through the what? What's inside the candle? Through the wick,

00:28:17 right? Into this area where there's a lot of air, and air is 20% oxygen, so combustion is taking

00:28:24 place right there. So think about that as we do the following experiment. This experiment,

00:28:32 where I have placed some dry ice into this beaker before

00:28:36 we started, and so the entire beaker now is full of carbon dioxide gas,

00:28:41 and what we're going to do is pour some carbon dioxide gas

00:28:45 onto the flame, again showing that carbon dioxide is heavier than air, it moves downward,

00:28:56 and showing that it does not support combustion. So let's do this one more time and see. There's

00:29:05 the candle, and we take the carbon dioxide and we pour it down,

00:29:17 and you see again the flame goes out, showing us that carbon dioxide does not

00:29:23 support combustion. That's why fire extinguishers are filled, one kind of them,

00:29:29 are filled with carbon dioxide. They're called carbon dioxide or CO2 fire extinguishers,

00:29:35 and that demonstrates once again that carbon dioxide does not support combustion. So what

00:29:42 we'll do next is go through a series of experiments that involve carbon dioxide

00:29:50 in the solid form, that is dry ice. I'll put my gloves back on. Uh-oh, I hear some

00:29:57 sound coming from some place. Uh-oh, Merry Christmas!

00:30:03 Ho ho ho ho ho! Merry Christmas! Ho ho ho ho ho! Merry Christmas! Ho ho ho ho ho! Merry Christmas! Ho ho ho ho ho!

00:30:24 Merry Christmas! Merry, Merry Christmas to you, Santa! How are you this evening? Very good.

00:30:30 I'm doing fine now that you're here. I sent you a long list of things that I wanted for Christmas.

00:30:36 I hope I was good enough that you brought them for me. Oh, you've been a very good boy this year.

00:30:40 Oh, well, I'm glad to hear that. Santa's brought you lots of presents this year. Oh my goodness, can I look

00:30:45 in there? Sure, go ahead and take a look. Is it safe to look in there? Sure. I got my goggles on. Very good.

00:30:50 All right, all right. Oh my goodness, what do I have here? What do we have here? Oh, it looks like a poster.

00:30:56 Oh my goodness, here's a poster. This is a commemorative poster for this 20th anniversary

00:31:03 lecture. Is this the only one you brought? No, no, everyone gets a poster. Everybody will get a poster.

00:31:08 Oh, that's tremendous, that's tremendous. Okay, and what do we have here? Another bag of goodies.

00:31:19 Oh my goodness, there is, there is a, there is a, what is, oh, it looks like a button. It is a button.

00:31:26 So, did you bring one for everybody? Everyone gets a button.

00:31:33 Well, you, you and your Al must have been very, very busy putting all of these things together.

00:31:38 There's a whole bunch of other goodies in here. Here's a set of instructions for doing experiments

00:31:43 at home. Let's see, there's one, two, three, four, maybe about a dozen different sets of instructions

00:31:51 for doing experiments at home. That's very good, very good. And other things that are in here,

00:31:57 we'll just be sure that everybody gets a copy. I mean, another copy gets a bag as they leave,

00:32:03 and a copy of this poster as they leave. And you and your Al have been very, very kind to me.

00:32:08 Merry Christmas!

00:32:21 Well, two of my best friends are here tonight. I'm really proud of that.

00:32:25 And I want to show you both another experiment that we will do with carbon dioxide.

00:32:33 We take a whole bunch of dry ice, and we put it inside what this looks like, a fish tank.

00:32:42 It's not really a fish tank, but it looks, you can use a fish tank at home if you have one.

00:32:46 You put this dry ice in there, and the idea, let me tell you what the idea is. The idea is that you

00:32:56 generate carbon dioxide gas and fill this container with carbon dioxide gas. Now,

00:33:02 at home, you don't have dry ice, so how can you generate carbon dioxide? What you do is you take

00:33:07 a small dish like this, and you put into it some baking soda and some vinegar, right? And you put

00:33:18 a little bit of the baking soda. How much is a little bit? Let's see. About that much. Cover the

00:33:23 bottom, okay? And then you take this, and you put it inside the fish tank. Make sure there's no water

00:33:33 in the fish tank, right? And then you take the vinegar, and you pour vinegar on top, and you see

00:33:40 it fizzes. That's because carbon dioxide is being released. You wait for about three or four minutes

00:33:47 so that the whole container is saturated with carbon dioxide gas. And then what you do is you

00:33:56 get some soap bubbles, and you know what happens when you blow soap bubbles, don't you?

00:34:05 Lots of pretty colors are on the surface of the bubble, and they float. But if you are very careful

00:34:15 in blowing the soap bubbles into this fish tank that has been saturated with carbon dioxide gas,

00:34:23 we'll see what happens.

00:34:34 You see the soap bubble doesn't sink all the way to the bottom. It just floats in the carbon dioxide

00:34:42 until it pops. You do this very gently, and you can see a lot of interesting things happening.

00:34:52 Not only are the soap bubbles floating in the carbon dioxide, but they are also pretty in color,

00:34:59 and they are changing sides. And I think, if I'm not mistaken, that Santa and his elves

00:35:05 have included the instructions for doing this experiment in the handouts that you brought.

00:35:09 Is that right, Santa? Oh great, very good, very good. So that's one experiment that you can do at home

00:35:16 if you generate the carbon dioxide from the baking soda and from vinegar. All right, so what

00:35:26 we'll try to do next is a set of experiments with some other household chemicals that you

00:35:34 might have access to. We'll take this bucket of hot water out of the way,

00:35:43 and what we'll do is get, what does this look like? What kind of cabbage is it?

00:35:51 Red cabbage, right? So what we'll do is try to chop off some of the red cabbage.

00:35:59 We'll do it this way, and you'll be very careful not to cut your fingers as you chop up

00:36:07 the red cabbage. Next, cut them off the other way.

00:36:17 And now you have some chopped red cabbage. What you need is a blender,

00:36:23 and you take the chopped red cabbage, or some of it anyway, you put it in the blender,

00:36:31 and the next thing that you do is, what's the next thing that you do?

00:36:38 Add water, right? Cover this with water,

00:36:43 and what do you do next? Ah, you put the cover on, right? Remember the safety regulations, right?

00:36:50 And you push the button,

00:36:58 and what has happened is that you've made yourself some red cabbage juice.

00:37:04 Now this juice is not for drinking purposes. What you want to do is to separate the liquid

00:37:10 from the chopped red cabbage, and you use a what to do that? You use strainer, right? Okay.

00:37:20 And so you've got yourself now the red cabbage juice down there. You have a lot of it, but

00:37:28 for to do the experiment you need more, so you add water. The color stays the same,

00:37:34 see? And the next thing that you do is you take a whole bunch of beakers or glasses,

00:37:41 plastic or otherwise, and you set them up like so with something to stir, and you put

00:37:49 some of the red cabbage juice into each one of them, about the same amount.

00:37:54 Do I have about the same amount so far?

00:38:00 Are they about even? How about that? Is that better? Okay, the next thing that you do

00:38:06 is you take the vinegar that we used over here, and you add the vinegar to one of the beakers,

00:38:15 and you see what happens is that now you have a way of telling whether certain household chemicals

00:38:22 are acidic or basic. You can tell the pH of those different substances. Vinegar has in it

00:38:29 acetic acid, so that is basic. The next thing that you try is what? Try some ammonia,

00:38:37 and ammonia is basic, so you know the color in basic solution. Then you can try a whole bunch

00:38:42 of different things. We'll try this one first. Is this going to be acidic or basic?

00:38:49 It's a carbonated beverage, right? So it has a carbon dioxide, so if we add some,

00:38:55 its color is going to be on the acid side, all right? Then you can try other household items.

00:39:03 Here's hide. Is this going to be acidic or basic? Well, don't guess. It's a 50-50 guess, right?

00:39:09 So you see its color is on the basic side, and you can try then milk of magnesia. You can try

00:39:18 vanish. You can try just about anything you want at home, provided two conditions are met. Number

00:39:26 one, the material that you try has got to be soluble in water, has to dissolve in water,

00:39:31 and number two, its own color should not interfere with the color of the juice. So if you take a

00:39:38 colored substance, for example, and try to test its acidity, that will give you a confusing result.

00:39:44 That's why I used this soft drink and not the other kind of soft drink, okay? All right, so,

00:39:53 and I also think, if I'm not mistaken, that Santa and his elves have put instructions for this

00:39:59 experiment, right Santa? Wonderful, wonderful. All right, so far we've been dealing with acid-base

00:40:07 behavior of different substances, and by the way, when you get done with this, all you have to do is

00:40:12 rinse everything down the drain with a lot of water, because everything is water-soluble that

00:40:18 we are dealing with here. Now what I'd like to show you, right next to Bucky, I have two pieces of

00:40:25 white paper. What I'm going to do is spray those pieces of white paper with a colorless and clear

00:40:34 liquid, and we'll see what happens. You ready, Bucky? Okay, we'll start with the bottom one first.

00:40:44 You see that? What does it read? It says 20th Christmas Lecture. That's because we used

00:40:52 something we call an acid-base indicator, and we painted those letters and numbers, and then we

00:41:00 sprayed it with a liquid, which is household ammonia, basically, that causes the color to

00:41:06 change. Now we have another one. We have another one that we're going to spray on top of the first,

00:41:12 and we'll see what happens when we spray it. There you go.

00:41:15 Oh, okay. Once again, if you know chemistry, if you want to study chemistry,

00:41:33 you get to the point where you know enough about it that you can do these different

00:41:37 experiments and have fun with them. As I told you from the beginning,

00:41:41 doing science is a lot of fun. So one other experiment we're going to do now, and ask

00:41:47 Fred to come out and help with this experiment. This experiment will be done at this end of the

00:41:53 table, and Fred will explain to you what he's doing. We've done some experiments with carbon

00:41:59 dioxide tonight, and it puts out fires. You know that, right? We've seen that happen. In this tube,

00:42:06 I've got a chemical which is very similar to carbon dioxide. It's called carbon disulfide,

00:42:12 and what we want to do is see if we can put out the fire of a match if we drop it down into this

00:42:19 tube. So what I'm going to do, I'm going to move the fire extinguisher a little bit so I don't kick

00:42:24 it over here, and I'm going to light a match, and then I'm going to drop it into the tube.

00:42:29 Now this will behave better in the dark, so I've only got one tube, so we'll do it in the dark just

00:42:35 once. Can everybody see the match? You take the stopper off, and here we go, and it goes out. So

00:42:44 that particular mixture of chemicals puts out a match just like the carbon dioxide did. But do you

00:42:52 see something else happening here? Can you see a reddish color coming up here? It's orange? Okay,

00:43:01 it's orange. That's one of the other chemicals that was in here is one of the chemicals that

00:43:07 makes smog when it hits the oxygen in the air, and that's exactly what's happening in here right now.

00:43:12 So I'm going to take this away before we gas anybody in the front row.

00:43:17 Take it to a safe place, Fred, and put it in a hood, I think, and that will

00:43:22 be the safe way of handling it. So let's move on and do another experiment by asking you

00:43:29 to look at these two beakers that have in them what looks like a green liquid, right?

00:43:34 And what we'll do to this is because, again, it is a very special time of the year, we'll add

00:43:43 a clear and colorless liquid, and you see what we get is a pretty combination of Christmas-type

00:43:50 colors. Again, if you know what you're doing in chemistry, you can produce a lot of pretty colors,

00:43:56 and you can handle those chemicals safely, as we must do every time that we handle them.

00:44:03 The next thing we want to try to do is to move over to this part of the lecture table,

00:44:08 and where we have a very large beaker full of water. The volume of this beaker is four liters.

00:44:14 Again, we make volume measurements in the metric system, and we use liters, not quarts or pints.

00:44:21 Those of you who need some help in converting from the metric system to the British system,

00:44:27 and vice versa, can ask your teachers and can ask your parents to help you with that conversion.

00:44:32 So what we'll do is add a slightly yellowish liquid, and see nothing much happens.

00:44:42 Then we take a clear and colorless liquid, we add this, and you see a lot of interesting

00:44:49 things begin to happen. We're mixing this. What does it look like? It looks like a tornado.

00:44:57 That's why we call this the orange tornado experiment. See, it's kind of yellowish at the top,

00:45:03 but then at the bottom it is a orange kind of a color. So that is then an example of how

00:45:13 an insoluble substance that's not dissolving in the water forms down the middle of the vortex where

00:45:21 the chemicals have been mixed. All right, we'll let that go for a while. By the way,

00:45:27 if we add more of this liquid, see it disappears. If you add more of this liquid, it comes back.

00:45:36 We add a lot of this.

00:45:40 So again, if you know what you're doing and you understand the different chemicals,

00:45:44 their properties, their behavior, you can have a lot of fun doing experiments of this type.

00:45:49 So the next experiment we want to try to do is one where I will put some disposable gloves on

00:45:55 because I want to protect my hands from possible damage. And what I'll do is take a liquid out of

00:46:04 this bottle and put it into this one liter beaker. What does this liquid look like?

00:46:13 Looks like syrup, but it's not syrup. Actually, it's a very poisonous liquid and we should never,

00:46:18 never eat it or bring it close to our mouth. We take another liquid from a different bottle

00:46:24 and add this. What does this look like? Looks like syrup too, but it's a slightly different color.

00:46:30 And what we learned tonight, I hope, is that chemical reactions don't happen unless you mix

00:46:37 them very well. Sometimes they happen very, very fast, as we saw in the explosions. Sometimes

00:46:43 they don't happen as fast. You just have to stir them up and watch out for changes that might be

00:46:50 happening. Now, wait a minute. This thing is going out of control. This, this is what we,

00:47:12 this is what we call polyurethane foam.

00:47:16 Polyurethane foam is made by mixing these two chemicals and it is a solid. It is a solid

00:47:23 and it's a rigid foam. It's used for insulation purposes. It's also used for making materials

00:47:30 inside of airplanes, like seats and other things like that. And it has very good practical

00:47:36 applications, but also it suffers because when it burns, if there's a plane crash or anything bad

00:47:43 like that, and this catches on fire, it releases gases that are very poisonous and very unhealthy

00:47:50 for us to work with. I want to show you that this has become very rigid. It's a solid.

00:47:57 Okay, so let's move on. And by the way, this should not be touched by the hand. That's why

00:48:05 I'm wearing these gloves until about four or five hours after the experiment, so that we don't get

00:48:12 our hands hurt by this experiment. So we'll go on now and use another example of a substance that

00:48:21 we call a polymer. This is a polymer called polyurethane foam. And what we have here is

00:48:26 another polymer called what? This is styrofoam. It's actually polystyrene. And what we'll do with

00:48:32 the polystyrene is take a colorless and clear liquid and add that to the cup and see what

00:48:39 happens. Whoops. You see that the bottom fell off. The bottom fell off and it looks like the

00:48:48 styrene, the polystyrene is dissolving in this liquid. This liquid is called acetone. And what

00:48:55 we have here is polystyrene in the acetone. But what I want to show you is that if you take a

00:49:03 whole bunch of styrofoam peanuts and try to add them there as fast as you can, that they also

00:49:13 disappear. So that's what happens if you do chemistry and you know what you're doing.

00:49:18 You can make certain things appear as we did here and make certain other things disappear. That's

00:49:25 the fun part of the fun of doing science and doing experiments the way that we have been

00:49:32 doing them. So now we'll do one more experiment with polymers. We'll take this liquid that looks

00:49:38 green in color and we take another beaker the same size and we put in it a small amount of a white

00:49:46 powder. See the white powder down there? And then very carefully we take the green liquid and we

00:49:52 add it over here like so. And then what we try to do is pour it back in.

00:50:01 And of course it doesn't come out. That's because this polymer that was in this small

00:50:08 vial absorbs many times its volume water. So this was water with food coloring added to it to give

00:50:18 us the special Christmas-like color. And the water gets absorbed in this and it becomes a gel.

00:50:24 Now this happens to have also practical applications. In fact, one of the important

00:50:32 applications that it has is its use as the absorbing material in diapers. And the instructions

00:50:39 that you will find in your packet, I think Santa brought these along too. You did, Santa, right?

00:50:46 That tell you how to do this experiment using the diapers that you have at home. All right, so let's

00:50:54 make sure you use the clean diaper though, all right? All right, now we'll go on and do a very

00:50:58 special experiment where we mix a clear and colorless liquid in this large beaker. We add

00:51:05 another clear and colorless liquid. And so far not very exciting things have happened.

00:51:12 Right, then we turn the stirrer on and we let this mix and we add the third one.

00:51:21 And what is happening there?

00:51:25 Is there anything happening there? I don't see anything happening. How come I don't see anything

00:51:32 happening? Because I'm not looking, you're right. So every time I look at it, it looks blue to me,

00:51:39 right? There it is, blue. Shall I look at it now? Right now? Right this minute? You sure?

00:51:47 Blue. Every time I look at it, it's blue. When do you want me to look at it? Right now?

00:51:53 Right now? You sure? Right this second? Blue. Now this is an example of what we call a chemical

00:52:02 oscillating reaction. And you're right, it changes colors. It's very pretty. It's one of many

00:52:09 oscillating reactions. It's a fascinating system. Again, that's why we study chemistry. That's why

00:52:15 we study science and try to do research to understand the behavior of these different

00:52:21 types of substances. I want you to know that this oscillating reaction was discovered by two high

00:52:28 school teachers in 1973. It's a fascinating system that we want to look at. All right, so let's move

00:52:34 on now and do another experiment. This experiment we're going to do in this spiral arrangement that

00:52:41 we have in front of us. I'm going to take a clear colored liquid and a clear and colorless liquid

00:52:48 and mix them together. You know, a lot of people confuse the words clear and colorless. You can

00:52:53 have a clear and colorless liquid like so, and you can have a clear and colored liquid like this one.

00:52:58 So what we'll do is mix those two liquids in this spiral assembly. We'll do this in the dark.

00:53:04 All right, so here comes both liquids.

00:53:23 This is an example, with the lights on now, this is an example of what we call a chemiluminescence

00:53:34 reaction. This is the release of energy in the form of light, not in the form of heat. If I touch

00:53:40 this, it's at room temperature. This is very similar to a reaction that all of you know about.

00:53:48 That is the firefly reaction. That is called bioluminescence. That's because there's an enzyme

00:53:54 in that fly that causes the glow to take place. Now there are other experiments that you can do

00:54:01 with chemiluminescence. This is not the only example. This is called a light stick,

00:54:06 and what you do is follow the instructions that are on the wrapper, and you bend it like so,

00:54:14 and if you turn the lights off, you can see that we have a very pretty glowing light stick.

00:54:21 And because it is the holiday season, we want to see if we can produce a different color.

00:54:32 All right, with the lights on now, Ben, I will ask Santa, he and his elves have included this

00:54:39 experiment in the bag. You did? Wonderful. That is wonderful that you've done that. What we're

00:54:44 going to do now is show you how versatile chemists and scientists are, and we're going to have a

00:54:51 special salute to the holiday season that we're in by asking Fred to bring some beakers out with

00:54:59 pretty colors and asking him then to present his special salute. These beakers have been set up

00:55:09 with great care because, well, first of all, I've got alternating red and green because it's

00:55:16 Christmas, and then you'll notice that the levels are all somewhat different,

00:55:20 and this is really an experiment where you have to pay attention with your ears as well as with

00:55:24 your eyes to see what's really going on and to make sense out of the reaction. So I have a stirring

00:55:29 rod here because we always need stirring rods in chemistry, and here's what we're going to do with

00:55:33 a stirring rod.

00:55:47 Merry Christmas, folks.

00:55:49 Well, we thank Fred, and I want you to know as we close this very special lecture that those of

00:56:06 you who would like your teachers to be doing some of these experiments can get the instructions for

00:56:13 doing the experiments by looking at these books that have been published by the University of

00:56:17 Wisconsin Press. They're called Chemical Demonstrations, a Handbook for Teachers of

00:56:22 Chemistry, and your teachers can do those experiments for you, especially if they have

00:56:29 the books. Now as a special salute to our very special guests, I want you to see that I have

00:56:35 prepared very special ornaments for them. Here's one, and here's another one, and I want Bucky to

00:56:44 have this one. I want Santa to have this one, and I want to thank you all for being my guests again

00:56:51 in my lab tonight. This has been a very special occasion for me, marking the 20th anniversary.

00:56:57 Thank you all, Merry Christmas, and Happy Holidays.