00:00:00 Hello, I am Harry Sello. It is my pleasure to introduce Tempest in a Test Tube, a television show which made its debut August 24, 1955, on KQED, Channel 9, the educational station for the San Francisco Bay Area.

00:00:20 Tempest was a series of 53 half-hour shows pioneering a new approach in which I, as lecture demonstrator, gave live, unrehearsed presentations of a series of chemical experiments.

00:00:35 These were designed to illustrate basic, simple chemical principles. The purpose was to stimulate an interest in chemistry by teenage students and by adults.

00:00:48 The talks and experiments had to be entertaining, educational, and simple. Spontaneity and liveliness were key to the approach.

00:00:58 All the experiments used in the shows were designed and constructed by members of the California section of the American Chemical Society.

00:01:07 The participants were employed by the Shell Development Company in Louisville and by Chevron Research in Richmond.

00:01:15 A grant of $52,000 from the Ford Foundation and National Educational Television permitted the filming of the first 24 shows of the series.

00:01:26 The management for the ACS consisted of Alan Nixon, section chair, Fred Stross, TV committee chair, myself as first emcee, and Aubrey McClellan, second emcee.

00:01:39 We four constitute the core of the present committee. The series was extremely popular then with KQED viewers of all ages.

00:01:53 The senior chemist committee of the California section today is determined to revive Tempest for the benefit of elementary schools, high schools, adult education classes,

00:02:06 ACS local sections, historical archives, TV stations, and similar organizations. We believe in chemistry as a second language.

00:02:18 While basic principles have not changed, practices have.

00:02:23 Forty-five years ago, such simple chemical demonstrations were not treated with the degree of safety considerations that they are today.

00:02:33 Today, even such simple demonstrations would be carried out with the proper regard for safety glasses, shields, protective gloves, laboratory coats, and visible fire extinguishers.

00:02:48 The principle of safety first would be explicitly present as part and parcel of a modern Tempest in a Test Tube.

00:03:02 The principle of safety first would be explicitly present as part and parcel of a modern Tempest in a Test Tube.

00:03:12 The principle of safety first would be explicitly present as part and parcel of a modern Tempest in a Test Tube.

00:03:22 The principle of safety first would be explicitly present as part and parcel of a modern Tempest in a Test Tube.

00:03:32 Tempest in a Test Tube, a series of experiments designed to explain the mysteries of chemistry and the laws that govern it.

00:03:57 Produced by KQED San Francisco, in cooperation with the California section of the American Chemical Society, for the Educational Television and Radio Center.

00:04:21 And now let's go to our laboratory and meet Dr. Harry Sello.

00:04:26 Hello. How would you like to see an experiment that used to have a kick in it?

00:04:34 A frog's leg.

00:04:37 It was work with a frog's leg over 200 years ago that led to the discovery of electricity from chemicals, which is the topic of this talk.

00:04:49 An Italian scientist by the name of Galvani was making a study of the structure of frogs, and in the course of his dissection,

00:04:59 he came across the fact that when he cut up a frog's leg with different metals, using different metals,

00:05:07 at certain times the way he touched it, he would get a quick kick in the frog's leg, even though it was dissected away from the frog's body.

00:05:17 This led Galvani to thinking, and he found that it was actually touching the nerve that's buried down deep in the muscles here that I'm pulling apart.

00:05:26 He found that it was touching this nerve and touching the bottom of the foot at the same time that caused the leg to kick.

00:05:40 This was the discovery, as I say, that electricity or something electrical was obtained from chemicals.

00:05:50 But it remained for another man about 10 or 20 years later to make a more thorough study of this result,

00:05:58 and he explained it very carefully, and that explanation is the way we look at the result today.

00:06:05 This man, second man, was Professor Volta.

00:06:10 Well, these names, you can probably guess, are in use in our language today.

00:06:15 Galvani has been used to talk about galvanic action, meaning action of a battery,

00:06:22 and Volta has been kept in our language by giving the name Volt to the unit of electrical pressure.

00:06:31 A battery will put out a certain amount of electrical pressure, and it's measured in volts.

00:06:38 Professor Volta recognized that it was the fact that Galvani used different metals, dissimilar metals, that gave the reaction in the frog's leg.

00:06:51 So he set about to do the following experiment, a very simple one.

00:06:57 He had a container in which he poured some ordinary salt, brine solution, sodium chloride.

00:07:10 He probably was a little neater than this, didn't splash as much as I did around here.

00:07:16 In this beaker, he placed two different metals, a copper strip and a zinc strip.

00:07:24 He then connected these two metals to a device which would tell him whether electricity was flowing.

00:07:32 Now, he did not use, in this case, the same sort of device that I'm using, this ammeter,

00:07:39 but when he made his little battery, he found that electricity would flow.

00:07:51 I have connected one lead to one side of this little ammeter, and the other lead, this clip and wire, to the other side.

00:08:00 And the needle kicks, indicating that there is an electrical voltage across, we say, these two plates, and electricity flowing through the wire.

00:08:15 Now, if this were not fixed up to read in amps or amperes of current, it would just be a galvanometer, another use of the name galvani, galvanometer, you see.

00:08:29 Galvanometer, a meter which measures the flow of electricity, after Professor Galvani.

00:08:36 So then, Professor Volta explained that what happened in the frog's leg was, when it was touched at both ends with two different metals,

00:08:47 one metal at one end, copper, and actually it was iron at the other end, a little tiny battery was set up,

00:08:54 which gave out some electrical current which flowed down through the nerve of the frog's leg.

00:09:01 This electricity caused the nerve to send out an impulse, and this impulse caused the muscles of the leg to suddenly contract, and caused the leg to kick.

00:09:14 Well, Professor Galvani, both of them actually, went on and made many studies on the effect of batteries, how you could make them, and just what they are,

00:09:24 and the knowledge as they compiled it is essentially the way we know it today, with very few changes.

00:09:30 So, we shall go on and look at some examples of electrical cells, or electricity from chemicals.

00:09:40 By the way, the setup which Professor Volta used, which I've just demonstrated, looks like this.

00:09:48 There's a beaker, and the beaker is a liquid, sodium chloride, we'll abbreviate that with its formula, NaCl, in water.

00:09:59 On one side, there was a copper strip, Cu for copper, let's make that a little bigger.

00:10:06 On this side, a zinc strip, reaching into the sodium chloride.

00:10:13 From each strip, there's a wire leading to the meter, so forth, a very rough sketch.

00:10:25 So when the circuit is made, electricity flows, the needle kicks on the meter, and you have the indication of the flow of electricity.

00:10:32 Three essential parts to a cell.

00:10:35 Two poles, two electrodes, I'm using these interchangeably, of different metals, or different materials,

00:10:42 and an electrolytically conducting liquid in between, I'll say that again, a liquid which can conduct electricity.

00:10:50 It's called an electrolyte.

00:10:56 Electrolyte.

00:11:04 What a battery essentially does is to make use of a chemical reaction to give a flow of electrons, which we call electricity.

00:11:16 Here's an example of a chemical reaction.

00:11:25 I'll put a little bit of zinc dust, the metal zinc, into this test tube.

00:11:39 Add to that a little bit of powdered iodine, an element, same as zinc.

00:11:57 Iodine is a purplish black solid, ground into a fine powder here.

00:12:06 Mix this up thoroughly.

00:12:11 The two together, dry, will not react.

00:12:16 Into this I put a thermometer, which reaches right down into the zinc and in the iodine.

00:12:21 This thermometer now says, difficult to see, let's take a reading on it before we put it in, it now says 27 degrees centigrade.

00:12:34 In one side of the cork I have a thermometer, in the other side there's a little tip of an eyedropper through which I'll squirt a little water.

00:12:43 Let's see what happens.

00:12:53 Watch closely, connect up the eyedropper and here goes the water.

00:13:00 A flash of purple vapor immediately as soon as the water hit the solids.

00:13:07 Now, the temperature shot way up and has hit the top, just about to the top of the thermometer, well over 105 degrees.

00:13:21 If you estimate this, it looks more like 120 degrees or so, but the heat was generated immediately as soon as the water hit the mixture.

00:13:30 I'll just take the thermometer out so that the mercury will not go too high, let it cool off.

00:13:36 Zinc and iodine react together rather quickly in the presence of water, generate a lot of heat.

00:13:41 Let's write that reaction down.

00:13:46 Zinc plus iodine gives zinc iodide.

00:13:57 You might say, where does the water come in?

00:13:59 If I wish to write the water, I must properly put the water above the arrow, indicating that it's more of a catalyst for this reaction than anything else.

00:14:09 But here we have a reaction in which a lot of heat was generated and was indeed a spectacular one, but what use can you make of it?

00:14:17 Let's look at the next experiment and see what use we can make of it.

00:14:22 This rather complicated looking beast is a beaker with a piece of zinc, now not a powder, but in the form of a metal plate.

00:14:35 Zinc metal immersed in the liquid.

00:14:39 The liquid is a solution of potassium iodide.

00:14:44 Here is a paper cup, a porous paper cup.

00:14:47 Sticking in that paper cup is a carbon rod, a hollow carbon rod.

00:14:53 Let me add some more potassium iodide to this beaker, bring the level up a bit.

00:15:06 There's the zinc.

00:15:07 Now, the other ingredient of this particular reaction, iodine.

00:15:16 I'll just spill that right into the paper cup.

00:15:33 Pretty near all of it.

00:15:35 Ought to be enough to show the result.

00:15:38 So we now have the zinc and the iodine in this beaker, but not quite touching, you see, as they were in the previous chemical reaction.

00:15:49 Zinc on one side, iodine on the other side, separated by this solution of potassium iodide.

00:15:55 Is there a chemical reaction? Let's see.

00:15:59 Here are two electrodes or two leads leading to this little flashlight bulb.

00:16:05 I'll connect one to the carbon electrode, the other to the zinc electrode.

00:16:12 There is something happening.

00:16:14 The light goes on.

00:16:16 Off.

00:16:18 On.

00:16:20 Off.

00:16:22 On.

00:16:23 Now here's another example of electricity from chemicals.

00:16:28 Let's just leave it on a moment.

00:16:31 Can this do something else besides light a bulb?

00:16:34 Yes, I think so.

00:16:38 I'll disconnect the bulb, put a couple more leads on this.

00:16:46 One from the zinc, one from the carbon, and this time hook up to a familiar object, a doorbell.

00:16:56 Answer the bell, somebody.

00:17:00 Disconnect.

00:17:02 Connect.

00:17:04 So this is a useful little battery.

00:17:06 It can ring a bell, it can light a flashlight bulb.

00:17:10 Making use of the reaction between zinc and iodine.

00:17:13 You see, what has happened is this.

00:17:16 This is the chemical reaction, zinc plus iodine, that's true.

00:17:19 But exactly what does happen, if you just put them together, it takes place quickly.

00:17:24 You can't get much use out of it except measure a temperature rise.

00:17:27 But we know that the zinc in this reaction transfers electrons from it to the iodine.

00:17:35 In the battery, we have arranged things by putting the zinc on one side and the iodine on the other side.

00:17:40 We have arranged things so that for the electrons to get from the zinc to the iodine, they have to travel through a wire.

00:17:47 We have then put this wire, connected this wire rather, to a bulb so that the electrons will light the bulb.

00:17:54 Also, it can ring a doorbell.

00:17:56 Let's look at some other examples of electrical cells and see how else electricity can be obtained from chemicals.

00:18:04 To do the next experiment, I'll have to have this ammeter here and our bell.

00:18:18 I've mentioned the fact that in an electrical cell, there are two dissimilar materials, two materials which are not alike.

00:18:30 They don't necessarily have to be two different metals.

00:18:33 In the case of the zinc and the iodine, there was a metal and a nonmetal.

00:18:37 But there are two dissimilar materials, an electrolyte connecting the two of them.

00:18:44 Here is a beaker with two plates in a frame, which I'll put into the beaker.

00:18:53 These two plates are not different plates. They are both lead.

00:18:58 Let me put the electrolyte in.

00:19:09 Concentrated sulfuric acid.

00:19:12 Immerse the two lead plates.

00:19:20 So right here is the beaker with two plates.

00:19:25 Is this a battery or a cell? We use the words interchangeably.

00:19:31 If we have to obey the rule that the plates must be different, then it is not a battery.

00:19:36 But let's test it.

00:19:42 Hook on to both of these plates and let's see if we can ring our bell.

00:19:51 There's one terminal connected and here is the last connection.

00:19:55 No ringing. No electricity flowing.

00:20:01 Can we make a battery out of this so it will ring a bell? Let's see if we can.

00:20:07 Here are two batteries hooked up in series.

00:20:12 These are one and a half volts each, three together.

00:20:17 I will connect one terminal of this, which we know are batteries.

00:20:22 I'll connect one to one lead plate and the other to the other lead plate.

00:20:27 Let's just leave that there and proceed on to the next experiment.

00:20:32 Carrying my little ammeter with me.

00:20:35 How simple can a battery be?

00:20:38 Here's one to try at home sometime.

00:20:42 A little iron washer. Penny.

00:20:47 I'll just tear off a little piece of this porous paper.

00:20:51 This is filter paper actually, but a little piece of cleaning tissue would work just as well.

00:20:59 I'll soak this piece of paper in acetic acid.

00:21:04 Some people may recognize acetic acid as being vinegar.

00:21:15 Put the penny on one side of the vinegar-soaked paper

00:21:20 and the iron washer on the other side, squeezing them together to make good contact.

00:21:26 Now, I'll hold a copper wire against the penny on one side

00:21:35 and another copper wire against the iron washer on the other side.

00:21:40 So here is the arrangement.

00:21:42 One lead coming from the copper penny, the other lead coming from the iron washer.

00:21:48 Let's see if we have a battery here.

00:21:53 Hook one side to the voltmeter, rather the ammeter.

00:22:00 And the other side now.

00:22:03 What happened here?

00:22:04 Ah, needle goes the wrong way. That means I have the terminals reversed.

00:22:08 I'll just reverse them back here.

00:22:12 Certainly is an electrical current flowing.

00:22:21 The same thing is happening. The needle indicates a deflection.

00:22:25 I'm just touching this lightly so that we won't hurt this sensitive meter.

00:22:31 There, touch it.

00:22:33 Off, on, off, on, off.

00:22:38 So, this penny battery is about as simple as you can get.

00:22:45 Copper penny, vinegar-soaked paper, and an iron washer.

00:22:50 We fulfill the rules.

00:22:52 Two dissimilar materials with an electrolyte in between.

00:22:57 It's not a very good battery because the electricity will not flow,

00:23:01 the electrons rather, will not flow around the circuit for very long.

00:23:06 It's an inefficient kind of battery, but nevertheless, it is a battery.

00:23:10 You see, this is the same thing that Professor Volta discovered

00:23:15 when he made his voltaic cells, Volta cells, years ago.

00:23:22 Let's go back and see what happened to the lead plates.

00:23:29 The batteries have now been charging the lead plates,

00:23:34 which gives away the experiment, sort of,

00:23:36 have been charging the lead plates for a couple of minutes.

00:23:41 Let's see if we got anything out of it now, or can get anything now.

00:23:46 I'll disconnect the charging batteries.

00:23:51 Hook up the bell again and see if we've gone far enough to see anything happen.

00:23:59 One plate, the other plate, one lead of the bell,

00:24:07 and now the key connection, keeping our fingers crossed.

00:24:14 The bell rings, and with a nice loud noise.

00:24:20 Off. Make the connection again.

00:24:23 On.

00:24:30 Just exactly what has happened.

00:24:32 This is the essence of an automobile-type lead storage battery,

00:24:39 which illustrates one of the biggest commercial uses

00:24:42 for batteries that we have today in existence.

00:24:47 The battery I had before, before I charged it,

00:24:52 was the two lead plates unaffected by the charging,

00:24:56 but that battery was what we call a discharged battery, a dead one.

00:25:01 You see, it's true that the plates were both the same, they were both lead.

00:25:06 When I charged the battery, I forced a chemical reaction to occur.

00:25:11 The chemical reaction was that I ran electricity from another source through the cells.

00:25:17 This is the charging source.

00:25:19 I ran it through the plates in the cell.

00:25:22 On one lead plate, there developed the chemical reaction between lead and oxygen.

00:25:28 We know that an electrical current going through water

00:25:30 will electrolyze water, liberating hydrogen and oxygen.

00:25:34 The oxygen reacts with the lead on one of the plates, and it's this plate.

00:25:39 I'll show you here that this is dark.

00:25:43 Where the lead is, it's light.

00:25:44 Turn the other one around, and it's quite light.

00:25:47 Here's the dark one.

00:25:48 Actually, it's brown, the characteristic color of lead oxide.

00:25:52 Now, we changed it by charging it from a cell with the same metals

00:25:58 to a cell with two different materials.

00:26:01 The different materials now are lead and lead dioxide.

00:26:06 Let's write this on the blackboard.

00:26:13 Here's our beaker.

00:26:18 Sulfuric acid as the electrolyte in between the plates.

00:26:25 Lead plates, actually, PB for lead.

00:26:28 But on the surface of one of the lead plates is lead dioxide.

00:26:37 That now makes it different than the other plate.

00:26:40 Now electricity can flow, and it did.

00:26:42 It rang the bell.

00:26:44 Before, electricity wouldn't flow because there was no lead dioxide.

00:26:48 So here is the cycle.

00:26:50 When you charge a battery, you make lead dioxide on one of the plates.

00:26:53 When you discharge a battery, the lead dioxide changes back to lead,

00:26:59 the same as the other plate, so that nothing can happen.

00:27:04 Here is a sample of a standard storage battery.

00:27:10 Cut away.

00:27:12 Lead plate, a separator usually made out of paper or plastic,

00:27:17 and another lead plate behind it.

00:27:23 Same thing as we have here.

00:27:25 Lead plate, a separator, which in this case is this little frame,

00:27:30 and paper is in here.

00:27:34 Space because of this frame and the other plate next to that.

00:27:39 When this is filled with sulfuric acid, it becomes a regular lead storage battery.

00:27:43 There are many kinds of storage batteries in use.

00:27:46 Not all of them are lead storage batteries.

00:27:48 It turns out that the lead storage battery is probably the most useful

00:27:52 because it can be made the most cheap,

00:27:56 cheaper than any other kind, and will probably last as long.

00:28:00 Here is a plate from such a lead storage battery.

00:28:04 You see it's not a solid plate.

00:28:06 It's actually a grid.

00:28:09 And in a regular battery, you have many, many of these plates,

00:28:14 24 plates, 36 plates, depending on how the battery is made.

00:28:19 In contrast with this so-called wet type battery,

00:28:22 we have what we call a dry cell battery.

00:28:24 Here's a cutaway of that.

00:28:26 That's what I used to charge this pair of plates before.

00:28:30 Here, one electrode is a carbon rod.

00:28:33 The zinc case is the other electrode.

00:28:36 In between is the electrolyte, in this case, ammonium chloride.

00:28:43 Well, let's look back and see just what was illustrated

00:28:48 in getting electricity from chemicals.

00:28:55 The principle of an electrical battery was discovered by Professor Galvani

00:29:00 over 200 years ago in an experiment, actually,

00:29:04 that he was doing with a frog's leg.

00:29:07 That is, the frog's leg kicked when he touched it with two different metals.

00:29:11 This was explained, really, by Professor Volta a short time later

00:29:16 when he built his cell composed of a copper strip

00:29:22 and a zinc strip in a solution of sodium chloride.

00:29:24 These were the essentials of an electrical battery,

00:29:27 two different materials with a conducting liquid in between.

00:29:34 We then saw how the use of a cell

00:29:40 could bring a chemical reaction to a sort of a useful point.

00:29:45 That is, in the case of the zinc and the iodine,

00:29:47 mixing the two together just generated a lot of heat,

00:29:50 which was interesting and made a thermometer,

00:29:53 the temperature in a thermometer rise.

00:29:57 But this was not as useful as it was

00:30:00 when it was done in the form of a battery right here.

00:30:03 This could make an electric light bulb light,

00:30:06 a little flashlight bulb, and make a bell ring.

00:30:09 Well, let's check this cell now.

00:30:11 It's been some 15 or 20 minutes since we looked at it before.

00:30:15 Let's see if it's still capable of lighting the little bulb.

00:30:21 Take off this extra lead.

00:30:22 Here is the, again, the one electrode, the carbon,

00:30:24 which reaches into the iodine.

00:30:27 Here is the zinc.

00:30:29 I connect first to the zinc, then to the carbon.

00:30:33 And the bulb still lights just as brightly as it did before.

00:30:38 So you might ask, will this make a good battery?

00:30:41 If so, why isn't it used?

00:30:44 The answer is it makes a good battery and it is used.

00:30:48 Here is one use of it as a demonstration.

00:30:50 Actually, it's not as practical as some of the other batteries

00:30:53 because it is difficult or expensive, let's say,

00:30:59 to build the elements of this cell,

00:31:01 the solid iodine with the zinc and this electrolyte.

00:31:04 It isn't as durable, as strong as it would be,

00:31:07 the automobile battery at present.

00:31:11 We saw that the automobile battery consists of the same materials

00:31:16 that make any battery, two different plates,

00:31:20 one lead, the other lead dioxide, the electrolyte, sulfuric acid.

00:31:26 When the battery is used or discharged,

00:31:30 the lead dioxide reacts and goes to lead.

00:31:34 The two plates come the same and it's no longer a battery

00:31:37 and has to be recharged.

00:31:39 These, then, are the ways of getting electricity from chemicals.

00:31:43 Thank you.