00:00:00 Hello, I am Harry Sello. It is my pleasure to introduce Tempest in a Test Tube, a

00:00:07 television show which made its debut August 24th, 1955 on KQED Channel 9, the

00:00:15 educational station for the San Francisco Bay Area. Tempest was a series

00:00:21 of 53 half-hour shows pioneering a new approach in which I as lecture

00:00:27 demonstrator gave live, unrehearsed presentations of a series of chemical

00:00:32 experiments. These were designed to illustrate basic simple chemical

00:00:38 principles. The purpose was to stimulate an interest in chemistry by teenage

00:00:44 students and by adults. The talks and experiments had to be entertaining,

00:00:50 educational, and simple. Spontaneity and liveliness were key to the approach.

00:00:57 All the experiments used in the shows were designed and constructed by

00:01:01 members of the California section of the American Chemical Society. The

00:01:06 participants were employed by the Shell Development Company, Emeryville, and by

00:01:11 Chevron Research, Richmond. A grant of $52,000 from the Ford Foundation and

00:01:18 National Educational Television permitted the filming of the first 24

00:01:23 shows of the series. The management for the ACS consisted of Alan Nixon, section

00:01:29 chair, Fred Strauss, TV committee chair, myself as first MC, and Aubrey McClellan,

00:01:36 second MC. We four constitute the core of the present committee. The series was

00:01:46 extremely popular then with KQED viewers of all ages. The senior chemist

00:01:53 committee of the California section today is determined to revive Tempest

00:01:59 for the benefit of elementary schools, high schools, adult education classes, ACS

00:02:06 local sections, historical archives, TV stations, and similar organizations. We

00:02:12 believe in chemistry as a second language. While basic principles have

00:02:19 not changed, practices have. Forty-five years ago, such simple chemical

00:02:25 demonstrations were not treated with the degree of safety considerations that

00:02:30 they are today. Today, even such simple demonstrations would be carried out with

00:02:36 the proper regard for safety glasses, shields, protective gloves, laboratory

00:02:43 coats, and visible fire extinguishers. The principle of safety first would be

00:02:49 explicitly present as part and parcel of a modern Tempest in a test tube.

00:03:37 Tempest in a test tube, a series of experiments designed to explain the

00:03:50 mysteries of chemistry and the laws that govern it. Produced by KQED San

00:03:57 Francisco, in cooperation with the California section of the American

00:04:07 Chemical Society, for the Educational Television and Radio Center. And now let's

00:04:19 go to our laboratory and meet Dr. Harry Sello. Hello. The topic of this talk is

00:04:28 freezing, melting, and boiling. To talk about these three physical processes, we

00:04:35 will use a very common compound, water, to the chemist H2O. Before starting the

00:04:43 experiments, for demonstration purposes, I would like to make a couple of

00:04:48 preparations here, which will take a little time to develop, so that we can

00:04:52 set them aside. The first is here. I have here a piece of iron pipe filled with

00:05:01 water and capped at both ends. Fairly thick iron pipe. It's been in this beaker

00:05:08 of dry ice for some time chilling. Well, I'd like to put it back in and set it

00:05:12 aside. Cover it up with dry ice. Cover the bomb and the table, of course, and put it

00:05:26 out of the way here on the side, where we can come back to it later. I said that we

00:05:36 were going to use water as the example to illustrate freezing, melting, and

00:05:40 boiling, and what they mean. One source of water is as a product of combustion.

00:05:55 This can be illustrated simply by the experiment in which this beaker is

00:05:59 placed over the candle, so, and the beaker fogs, develops a fog over its

00:06:10 surface, a fog of water vapor. The water vapor comes from the combustion of the

00:06:17 fuel in the candle. Well, this is one form of water, water vapor, or water as a gas.

00:06:26 Let us proceed on a little further and consider some other properties of water.

00:06:43 Light my burner here, and I'll have to hold it against this dark background of

00:06:50 the stand to see where the flame is set properly. There. I could make this flame

00:07:01 yellow and visible, but that wouldn't be a very efficient flame. Perhaps if I put

00:07:11 this black background behind it, it might even be seen more easily.

00:07:29 This apparatus, which is shown here, is an apparatus which will perform, as soon as

00:07:37 the water gets hot, in which we will perform a distillation. It consists of

00:07:42 essentially three parts, a flask filled with dark liquid, which is water dyed to

00:07:48 make it visible, a condenser, or some engineers call it a heat exchanger, and a

00:07:56 receiver. In the flask is placed a thermometer through the stopper. Now, as

00:08:04 soon as this gets hot enough to show the action, we'll be able to illustrate

00:08:09 the various parts of this experiment.

00:08:21 Already some water vapor is developing on top of the flask. Well, this may take a

00:08:26 few minutes to come to a boil. I think we should proceed on to this next small

00:08:31 little demonstration here and illustrate the third form of water, that is the

00:08:38 third of three forms, the first being water vapor, the second being water

00:08:42 liquid, which is in the flask, and here water solid or ice. Now, this wasn't a

00:08:53 very complicated experiment, admittedly. It consisted in dropping a cube of ice

00:08:58 into a beaker of water. The simple principle being illustrated here is that

00:09:04 the ice floats on the water. This is a very important property. It means, first

00:09:10 of all, that ice is less dense than water, otherwise the ice would sink, and

00:09:16 indeed, you and I should be very glad for the fact that ice is less dense than

00:09:21 water, because if it weren't, we probably would not be able to live in the, in most

00:09:26 of the United States for most of the year as we do now. What I mean is this. We

00:09:33 live in the temperate climates, that is, the climates in which the large part of

00:09:36 the country gets some cold temperature during the winter. Water freezes. We hit

00:09:42 freezing temperature very readily during winter. Well, it is fortunate that when

00:09:46 water freezes, the ice floats so that a river or a pond or a stream of some sort

00:09:52 will freeze from the top down. That is, a layer of ice will develop, and pretty

00:09:56 soon that ice will go a little deeper, and perhaps a river, a deep river, may

00:10:00 never really freeze completely. Just think of the reverse situation. Supposing ice

00:10:04 were not less dense than water, so that the ice would freeze from the bottom up.

00:10:10 That would mean that during a cold winter, all the fish would be destroyed

00:10:15 in any given river or any lake, since they would not have any place to escape

00:10:19 to. All the water would get frozen from the bottom up. Rivers would stop flowing.

00:10:24 We would lose hydroelectric power. Well, all sorts of trouble like that, so that

00:10:30 we could not live very comfortably in the real cold parts of the country, even

00:10:33 though they may be nice during the rest of the year. And probably a river that

00:10:37 was frozen through because it froze from the bottom up never would get thawed out

00:10:40 during a long summer, even, because it would just be too much ice to freeze, too

00:10:45 thawed out, rather. It would be too much there to begin with. So we are indeed

00:10:49 happy and lucky that Mother Nature has provided it for us that water freezes to

00:10:54 ice, which is less dense than the original water, and floats on top. Now, in

00:10:58 this distillation here, I already hear some perking occurring, and lots of

00:11:05 droplets are developing around the neck of the flask. The thermometer still hasn't

00:11:14 risen. Well, no, I should take that back. Here it is. It's just past the 82, 84

00:11:19 mark and rising sharply, 88, 89. Now somebody may buy if they're in the stock

00:11:26 market, I suppose, but the temperature hasn't gotten up to the right point yet.

00:11:30 Now the water is clearly boiling very easily, perking along rather merrily.

00:11:37 Vapors are rising here. They're pretty well collected around the stopper. And the

00:11:41 first bits of vapor have appeared in our condenser. And the distillation is

00:11:47 now working. There's water, warm water droplets coming over here. This process

00:11:53 is distillation. To distill means to make use, to separate liquids while making use

00:12:05 of their boiling. I've sort of simplified the definition, but it's good enough for

00:12:10 our purposes here. This is a very common apparatus. It has many practical uses.

00:12:15 Already, here is one. Water is dyed in this flask. Supposing you wanted to get

00:12:20 pure water from something that you couldn't drink. Well, by boiling it, making

00:12:24 steam, letting the steam condense in the condenser, collecting the water which

00:12:30 results, we now have clear water, non-dyed water. We have separated the pure

00:12:34 water from the dye, and the dye will remain back here. This process will

00:12:39 continue until the water has mostly all boiled over. As I say, this is a very

00:12:45 common practice in industrial uses. One of the most common is to separate

00:12:51 alcohol from its fermentation product, to purify drinking alcohol from water. It

00:12:58 can be done by distillation. Another is still the separation of many petroleum

00:13:04 products. Petroleum products can be separated into their liquid fractions by

00:13:12 water, also by distilling such as we do in water. I was caught up here because I

00:13:18 wanted to point out that a distillation operation is usually concerned with a

00:13:21 lot of heat, hence water comes about from all sorts of sources. So the process

00:13:30 of distillation then illustrates the fact that water can be separated

00:13:34 from impurities. Muddy water could be so separated, you see, you could leave the

00:13:39 mud behind and distill the water over. Three states of water, liquid, gas, and

00:13:44 over here in this other one, solid. These are the three forms in which water will

00:13:51 exist. Let's look further into this matter of water expanding when it

00:13:58 freezes. First I better turn this off.

00:14:06 Stop our distillation. Proceed over here to the next experiment. Here we have a

00:14:16 flask containing water again, only dyed blue to me. It looks dark to the camera

00:14:26 I'm sure so it can be seen. Flask is completely full right up to the top and

00:14:31 in this flask has been jammed a cork stopper containing this long hollow tube

00:14:39 so that the squeezing of the cork stopper into the liquid forced the

00:14:43 liquid right up into the tube. It looks very much like an oversized kind of

00:14:47 thermometer, water thermometer, with a very great big bulb and with a cork in

00:14:52 the middle of it. Ah, there goes our bomb. Let's go over and take a look at it.

00:15:03 Bring it over here where we can see it.

00:15:22 Kind of cold to hold. Let's get a glove here. There, there is a crack the length

00:15:36 of the bomb extending from cap to cap through which can be seen the ice.

00:15:42 There's a little piece of scotch tape with a label pasted on so as to mark the

00:15:48 bomb that it was full before I started. That scotch tape isn't holding anything

00:15:52 anyway. The crack extends from all the way the length of the bomb. Now this is a

00:15:56 very strong piece of pipe. It takes several thousands of pounds to break a

00:16:03 piece of pipe like this so the force of the expanding ice or expanding water and

00:16:08 coming to ice or freezing to ice is just tremendous. I have over here some samples

00:16:14 other bombs that I broke at another time just to test out this experiment. These

00:16:28 now have been thawed out you see and they were emptied so we can look into

00:16:32 them a little more closely. Here's one which developed quite a crack, even a

00:16:37 bigger one than this first one we did here. In fact this crack was so big that

00:16:42 it just split the cap right off. Just broke the cap. Here's another. Did the

00:16:49 same thing, split the length of the bomb and this was the cap that was on it

00:16:52 before. It was a slightly different kind of cap. It had a plug in it and there was a

00:16:55 hole in the top. This shows that it's very difficult to keep water from

00:17:01 freezing when the temperature is right. When it's at freezing at zero degrees C

00:17:06 or centigrade rather, water just wants to freeze and it's very hard to prevent it

00:17:10 from doing so. As a matter of fact in order to prevent the freezing of water

00:17:15 you can apply a lot of pressure. You see if the water expands while it freezes

00:17:21 then keeping it from expanding would keep it from freezing. This can be done

00:17:27 if enough pressure is applied, if this pipe were strong enough for example, but

00:17:33 this would have to be a tremendous pressure. To change the freezing point of

00:17:36 water by one degree would take something like, oh, 1,500 pounds per square inch of

00:17:44 pressure. A hundred atmospheres, 1,500 pounds per square inch or more correctly

00:17:49 let's say about 1,470 pounds per square inch of pressure to keep water from

00:17:55 freezing. That is to keep it from freezing at zero degrees to make it

00:17:59 freeze one degree lower. So the power of expanding water is indeed tremendous and

00:18:04 those of you who have lived in the parts of the country where winter gets

00:18:08 kind of cold, you may recall that you lost water supply during the winter

00:18:12 because of the splitting of water pipes. Very difficult to stop this. Let's go

00:18:17 back and look at our little experiment here that was interrupted.

00:18:27 Now I would like to mark, ah, I see something. Before I was wondering where

00:18:31 this heat came from, this reminded me. Before we start, I'd like to take this

00:18:35 can and put it on the hot plate here. That hot plate has been sitting here

00:18:40 kind of hot, so any sizzling noise you may hear during the course of the

00:18:45 discussion is due to the can. They're starting to sizzle now, there's water in it.

00:18:51 Now I'd like to mark this point at which the level of the liquid is in the tube

00:18:57 right now. There's a little grease pencil mark. And in the beaker, I'll put a little

00:19:09 bit of, not dry ice this time, but regular ice or sometimes called wet ice.

00:19:19 By the way, those of you who are fond of picking up a chunk of ice and tossing it

00:19:31 in your mouth and like the pleasure of melting ice, I would suggest that it's

00:19:36 not a very good idea to do this in the laboratory at all. I mention that because

00:19:40 I just had the urge to do so myself, also being kind of warm. This is not a very

00:19:45 good practice and should be strongly discouraged because you never know what

00:19:49 got into the ice. To this ice, I will add a little bit of salt.

00:20:02 The purpose of the salt in ice is to give a mixture which will give a lower

00:20:08 temperature than just the ice alone. If you've ever been in a large city during

00:20:13 the winter, the streets sometimes glaze over with a layer of ice. So not even

00:20:18 sometimes. I recall in Chicago this happened quite often. Well, this makes for

00:20:24 very tricky driving. So what happens is that the Department of Streets will send

00:20:30 out a truck with a lot of salt on it and they'll just go around shoveling the salt

00:20:33 on the glaze and soon you'll find that the ice has melted. You see, ice or water

00:20:39 with salt in it will freeze at a lower temperature than pure water. So adding

00:20:43 salt to ice makes it go down to a lower temperature. Now that's enough for a

00:20:50 starter. Lower this right down into the freezing mixture, firm, and pack in a

00:21:02 little bit more around the other side.

00:21:10 By the way, if you've ever made ice cream at home, your your home ice cream freezer

00:21:15 uses an ice salt mixture. Pack a little more salt in it.

00:21:28 It has a tendency to cake a little bit here.

00:21:39 And we'll just put a little more in for good measure. Right around the top.

00:21:52 Now, see what happened out here. Ah! Something is already visible. The level

00:22:00 of liquid has already dropped about a half an inch below the previous mark.

00:22:06 This is the important point. We started up here. It has dropped. Upon putting it

00:22:13 into ice salt mixture, upon chilling, this means that the water in the flask

00:22:18 has contracted, gone to a smaller volume. Well, while this is going on, this

00:22:26 contraction, let's go on to this next little experiment here and then come

00:22:31 back and take a look at the first one. The next experiment is one in which

00:22:40 we're concerned with the physical process in which gaseous water, or steam,

00:22:47 changes back into liquid water. This process is called condensation, to

00:22:54 condense. Condensation is a description for just that, steam changing back

00:23:02 into liquid water. Or, not necessarily steam, any gaseous vapor, like gasoline

00:23:08 vapor, changing back into liquid gasoline. It's the reverse of boiling or

00:23:13 vaporization. Condensation, the changing of the vapor back to the liquid. Now, in

00:23:20 here, in this steel can, is a, about an inch of water in the bottom, which has

00:23:28 been sizzling here for some time. Now, I don't know, it's probably been boiling

00:23:36 long enough now. I can see down into it. Yes, it is boiling. Let's try and try the

00:23:43 experiment and see what happens.

00:23:50 The can is kind of hot. Take it off the heat, put it on the pan here. Now, the important

00:23:57 part of this experiment, if you should ever repeat it, is take it off the heat

00:24:01 before putting on the lid. Do not put the lid on the can when the can is on the

00:24:06 hot plate, which reminds me that I'll just turn this thing off, it's generating an

00:24:10 awful lot of heat. I now cap the can and take my sponge, which has been soaked

00:24:28 with a little bit of water, squeeze it out on the can. The can is beginning to

00:24:37 make noises like it doesn't like this process. It's certainly beginning to

00:24:48 collapse, and it's caving in on this front end there. Add a little bit more of

00:24:59 water, make sure it gets good and chilled. Back. Oh, it's pretty well caved in on the

00:25:12 front of it. Let's just see if we can do any more to it. Oh, it's about as cool as

00:25:20 it wants to get. It looks like somebody has grabbed it right in its middle and

00:25:26 given it a great big squeeze and crushed it. The following has happened.

00:25:31 The water inside has boiled, the steam risen out, washed out all the air ahead

00:25:38 of it, so that nothing was left in the can but just steam and liquid water. When

00:25:43 I capped it and poured cold water onto the outside, I condensed the steam, the

00:25:49 process of condensation. I condensed the steam, it now then left a vacuum in the

00:25:55 can so that the air pressure on the outside of the can proceeded to collapse

00:25:59 it. If I had boiled this just a little bit longer, maybe perhaps five or ten

00:26:03 minutes, and really gotten up a good head of steam, then, and made sure I washed

00:26:08 out all the air from the inside, then crushing it would have even crumpled it

00:26:11 up more. The more vacuum there is on the inside, the more this will crush. This

00:26:16 illustrates a point which will be discussed at another talk a

00:26:20 little more deeply, namely that the atmosphere exerts a pressure on the can.

00:26:25 Something like almost 15 pounds for every square inch. So there, if you

00:26:32 figured out the dimensions of the can, there's a hundred square inches on

00:26:35 this side, and another hundred here is 200, and perhaps another hundred all

00:26:38 told, 300 square inches times 15 pounds would be 4,500 pounds on this can. Well,

00:26:46 that's well better than two tons, and no wonder the can wants to crush.

00:26:53 Concerning this matter of atmospheric pressure, I would like to leave you with

00:26:58 a small problem. See if you can't, from your surface area of your body, the amount

00:27:06 of area exposed to the atmosphere, figure out how much pressure, or better still,

00:27:11 how much force must be exerted on the area of a human body. When you come up

00:27:17 with an answer, it had better be large. Let's go on, well, then further ask

00:27:23 yourself, why is it I am not mashed to a pulp by this tremendous force? Let's go

00:27:28 on and see what's happened in our previous experiment. The water in the

00:27:33 column has now dropped almost a full inch below the previous mark. Recall that

00:27:41 at the previous mark, the water was at room temperature. It has been chilled, not

00:27:46 quite to freezing, and it has contracted until it has dropped almost an inch

00:27:51 below the previous mark. Let's just put a mark here to show how far down it has

00:27:56 gone. This shows that water reaches its maximum density at just before it freezes.

00:28:04 Just about four degrees above zero, water reaches its maximum density. It

00:28:10 shrinks to its smallest volume, and then the next thing that happens after it

00:28:14 cools down to freezing is that the water freezes and then expands. We have shown

00:28:19 this first contraction. Let's now see if we can go a little further with this

00:28:25 experiment and hasten this freezing process a little bit. Instead of using

00:28:31 just the ice salt that I used before, which is still left in here, I'll throw a

00:28:35 little carbon dioxide or dry ice right on top of it, just to make it a little

00:28:39 faster. Keep your eye on the column of liquid. You don't want any of these big

00:28:49 chunks.

00:28:59 A little bit more.

00:29:09 And finally just a little bit more than that even. Now it's pretty well covered

00:29:15 with dry ice. Remember this is the mark at which it reached. It's pretty close to

00:29:25 us, contracted pretty much as much as it wanted to. I see some of this dry ice is

00:29:30 falling out of here now. Big chunks in there now on top. Now this device which

00:29:38 measures the contraction and expansion, or another word for expansion would be

00:29:45 the dilation of water, is called a dilatometer or dilatometer, if you will,

00:29:52 something which measures dilation. It's a very common device in certain phases of

00:29:59 chemistry which makes use of this property of expansion to measure what

00:30:05 goes on. Now as this freezes, I already see that there is a tiny amount of

00:30:12 increase in height. It has now begun to go back up again, but let's leave that

00:30:18 and summarize, picking this up at the very end of our summary. We have shown

00:30:23 three processes, freezing, melting, and boiling. Freezing and melting being just

00:30:30 the opposite. The boiling we demonstrated, we used to demonstrate a distillation

00:30:35 apparatus which separated pure water from dyed water. In fact I was dying to show

00:30:42 you that experiment. This is a common industrial process. We went on further to

00:30:49 show that water changed still into another form, ice, solid form, caused

00:30:54 expansion when it did happen, and this expansion was strong enough to split

00:30:59 iron pipes, one of which we showed here. Then the condensation of water was

00:31:06 demonstrated by cooling the steam in a can, which resulted in the can being

00:31:11 crushed by atmospheric pressure. And finally we saw that upon cooling, the

00:31:18 water, which started at the top mark, contracted, went down as far as the

00:31:22 bottom mark, where then it began to freeze, and began to rise due to the

00:31:26 expansion, and went up to as high as the original mark, and now even higher, and it

00:31:31 will continue to rise as it continues to freezes. To freeze rather. Thank you.

00:31:48 ♪♪♪

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00:32:20 This is National Educational Television.