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.

00:00:21 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.

00:00:36 These were designed to illustrate basic, simple chemical principles.

00:00:42 The purpose was to stimulate an interest in chemistry by teenage students and by adults.

00:00:49 The talks and experiments had to be entertaining, educational, and simple.

00:00:55 Spontaneity and liveliness were key to the approach.

00:00:59 All the experiments used in the shows were designed and constructed by members of the California section of the American Chemical Society.

00:01:08 The participants were employed by the Shell Development Company, Emeryville, and by Chevron Research, Richmond.

00:01:16 A grant of $52,000 from the Ford Foundation and National Educational Television permitted the filming of the first 24 shows of the series.

00:01:27 The management for the ACS consisted of Alan Nixon, section chair, Fred Strauss, TV committee chair, myself as first emcee, and Aubrey McClellan, second emcee.

00:01:41 We four constitute the core of the present committee.

00:01:46 The series was extremely popular then with KQED viewers of all ages.

00:01:54 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, ACS local sections, historical archives, TV stations, and similar organizations.

00:02:14 We believe in chemistry as a second language.

00:02:19 While basic principles have not changed, practices have.

00:02:24 45 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.

00:03:18 .

00:03:43 .

00:03:50 Tempest in a test tube, a series of experiments designed to explain the mysteries of chemistry and the laws that govern it.

00:04:00 Produced by KQED San Francisco.

00:04:09 In cooperation with the California section of the American Chemical Society.

00:04:18 For the Educational Television and Radio Center.

00:04:24 Now let's go to our laboratory and meet Dr. Harry Sello.

00:04:31 .

00:04:42 Hello. This experiment illustrates the relationship between chemistry and electricity, in one way that is.

00:04:53 This is the topic of the talk this time, chemical conductors of electricity.

00:04:59 Here I have a set of batteries which put out six volts of electricity.

00:05:06 These are connected to an induction coil which steps up the six volts to many thousands of volts.

00:05:12 The amount necessary to make the light bulb glow.

00:05:17 Like that.

00:05:20 The relationship between chemistry and electricity comes around in the following way.

00:05:25 When I made the connection, electrons were caused to flow through the bulb.

00:05:30 These electrons bounced along the sides of this fluorescent bulb.

00:05:35 And in so doing hit the chemical which is coating the walls of the bulb.

00:05:40 This chemical has the property that it will glow when electrons hit it.

00:05:45 It is very similar to the chemicals which are, one of the chemicals which is used on a television screen.

00:05:51 Electrons bouncing against this chemical make it glow.

00:05:54 So from electricity through a chemical reaction that is glowing due to electron bombardment,

00:06:02 we can show the connection between the two, that is chemistry and electricity.

00:06:08 In this next experiment we can show the same thing only in reverse.

00:06:15 On this dial, this dial will indicate, I should say, when there is an electrical current flowing.

00:06:24 There.

00:06:26 By picking up and turning around this little cell facing the light, I can make the needle swing.

00:06:33 I'll cover it.

00:06:36 The needle comes down to zero.

00:06:38 I uncover the little cell.

00:06:40 The needle goes up over 20, over the scale range, showing that electrical current flows.

00:06:48 Once more.

00:06:49 Zero.

00:06:50 Covered.

00:06:52 Over 20.

00:06:54 I'll put it face down so no light can fall on the cell.

00:06:57 What has happened here is that the light falling on the little photo cell, photoelectric cell is another word,

00:07:05 causes electrons to flow which register on the meter.

00:07:09 So here we have the reverse.

00:07:11 Light causes electrons to flow due to the reaction of light with the chemical of the photo cell.

00:07:18 The chemical of the photo cell is something usually like selenium, one of the elements in a periodic table.

00:07:26 There's a slight reading now because the photo cell is not quite lying face down.

00:07:30 It's a little tilted.

00:07:31 If I flatten it out, it'll go down to zero.

00:07:34 So here are the two directions.

00:07:38 Electricity causes electrons to flow, makes the bulb glow.

00:07:42 In reverse, light falls on the photo cell, makes electricity flow.

00:07:48 By these two experiments, we can then see that there is an intimate connection between chemistry and electricity.

00:07:55 In a sense, the material of the bulb and the material of the photo cell can be called chemical conductors of electricity.

00:08:03 Let's go on and look a little bit more at this business of chemical conductors of electricity.

00:08:11 To do this, let's examine a little bit about the nature of electrical current or the flow of electrical current.

00:08:20 I'll take this piece of filter paper, which is a porous kind of paper, and soak it with a chemical.

00:08:32 Get it good and wet.

00:08:42 And blot it here to take off all the extra liquid.

00:08:50 These pieces of paper toweling.

00:08:54 There, that gets off the extra liquid.

00:09:02 Put my now damp piece of paper on top of this inverted pie pan.

00:09:10 Making sure it plasters on the pie pan in all directions.

00:09:14 Here is a source of electricity.

00:09:17 This is a transformer which is connected to the 110 volt house voltage.

00:09:22 One lead, electrical lead, I'll place on the pan.

00:09:29 Now, as soon as I touch this lead to the paper to complete the circuit, this is what it is.

00:09:37 The 110 house voltage goes into the transformer.

00:09:40 The transformer steps it down, that is, decreases it to about 24 volts so that it can be handled.

00:09:47 So at the end of these leads, or across the ends of these leads here, we have 24 volts of electricity.

00:09:56 I'll hold the paper down.

00:09:58 Now watch what happens.

00:10:01 Nothing, yet.

00:10:04 Ah, small matter.

00:10:07 There is a little switch here that has to be pushed.

00:10:12 This energizes the transformer.

00:10:14 A necessary operation.

00:10:17 Nothing damaged.

00:10:19 Now, repeat the operation.

00:10:21 Hold this down and...

00:10:32 These lines, you'll notice, are dotted lines, or more correctly, dashed lines.

00:10:38 That is, there's a dark spot, light spot, dark spot, light spot, and so forth.

00:10:43 Remember, this is the alternating current.

00:10:46 Let's leave that.

00:10:50 Disconnect now.

00:10:52 And look at this next setup using a battery instead of the alternating current and the transformer combination.

00:11:00 This doesn't make any difference having this lead on.

00:11:02 I will just connect one terminal of the battery here.

00:11:05 Don't have to worry about this because it doesn't need a switch.

00:11:11 Just now I can hold it because there's no damage, no danger.

00:11:14 Now the same operation.

00:11:20 Notice now the line is solid.

00:11:24 No dashed lines.

00:11:25 Well, here's a slight little dash where my pen sort of skipped the paper, but they're solid lines.

00:11:31 We now see the difference between, or see an evidence for the difference between alternating current and direct current.

00:11:38 AC and DC.

00:11:41 This paper has been soaked with a mixture of potassium iodide, a chemical, and starch.

00:11:48 When electrical current is made to flow through potassium iodide, the iodide ion changes into iodine, the element iodine.

00:11:59 This reacts with starch, forms a dark color.

00:12:03 Because the alternating current changes its direction 60 times a second in direction,

00:12:11 we have small periods, tiny periods when the alternating current actually is off.

00:12:16 That is, it goes from left to right, let's say, flips over from right to left.

00:12:19 In that instant when it flips over, there's a tiny fraction of time when the current is actually off.

00:12:24 At this moment, there can be no reaction with the chemical on the paper, only when the current is flowing.

00:12:30 The result is that every time the alternating current changes its direction, you have a negative result, no chemical action.

00:12:39 Every time it flows, you have a positive chemical action.

00:12:41 The iodine starch color forms, so you have a dashed line.

00:12:45 The alternating current sort of wrote its own signature in the form of a dashed line.

00:12:50 However, in a direct current, the current is flowing all the time from a battery, let's say.

00:12:55 It never goes off until I break the connection, so that there's no reversal of direction.

00:13:00 Hence, there is chemical reaction all the time, so there is the color of iodine and starch all the time.

00:13:06 The black lines compared to the dashed lines.

00:13:09 Well, you see, here is another way of showing not only the difference between alternating current and direct current,

00:13:15 but the fact that electrical currents can cause a chemical reaction to happen.

00:13:20 The iodide ion, as I mentioned, is discharged, is changed to iodine, which then discharges the color of starch-iodine complex,

00:13:29 a new compound which is brown.

00:13:33 So we set up a series of chemical reactions right there by using a little bit of current.

00:13:38 So even alternating current or direct current can be used to show that there is a relationship to chemistry.

00:13:47 The battery itself, by the way, you see, has a chemical reaction going on in this.

00:13:51 We talked about this in a previous talk.

00:13:54 The chemical reaction generates the electricity that we use here.

00:13:58 So we now showed this matter of the conducting of electricity through the use of a chemical reaction.

00:14:06 Let's go on and look at this business of conducting a little more deeply in this next series of tests.

00:14:16 In this setup right here, we have a similar one to the transformer alternating current setup here.

00:14:24 Only we have a meter which will read the amount of volts of electricity every time current is made to flow.

00:14:32 At the same time, there is a little electric light bulb attached to this meter, which will light up if current flows.

00:14:39 Just to show that this will happen, I'll take the two leads,

00:14:43 being very careful not to handle the metal leads because I'll certainly get a charged talk here.

00:14:50 Notice that the needle reads just about 120 volts while the light bulb goes on.

00:14:55 This is the house voltage at this time, 120 volts.

00:14:58 Some places it's 110, other places it's 115.

00:15:01 It just varies around that number.

00:15:04 If I connect these two, two of these electrical leads in the tube,

00:15:09 then all I need to do is connect these two leads in the tube.

00:15:17 All I need to do to make electricity flow is to put something which will conduct electricity across these two pointers sticking out here.

00:15:36 Let's run a few tests.

00:15:39 Here is a list of chemicals or materials which have been placed out here ready to go.

00:15:44 The first is a piece of rubber.

00:15:50 I'll touch that to both leads.

00:15:53 No effect.

00:15:55 I already showed that the circuit is live because it can light the bulb.

00:15:58 Rubber, no effect.

00:16:00 Well, on the board, I already prepared the names of these.

00:16:02 Let's just write this down.

00:16:05 Rubber cannot conduct the electricity, so we will call it a non-conductor.

00:16:12 I'll abbreviate conductor.

00:16:17 Next, glass.

00:16:22 Also no effect.

00:16:25 Non-conductor, zero marks.

00:16:30 Copper, maybe you can guess some of these.

00:16:32 Here's a piece of copper tubing.

00:16:36 There's a wavering because I'm not making a very good contact just touching it.

00:16:40 There it is.

00:16:41 It hits about 120 volts, showing that it's a good conductor.

00:16:43 Light bulb lights.

00:16:45 Copper is a conductor.

00:16:51 Ordinary salt, sodium chloride, dry salt.

00:16:58 Non-conductor.

00:17:00 Non-conductor.

00:17:02 Let's just wipe this clear to make sure that there's no salt sticking on.

00:17:07 Follow up the next experiment.

00:17:09 Salt, dry salt, non-conductor.

00:17:16 Here is some distilled water.

00:17:19 Bottled distilled water.

00:17:25 Now this may surprise you.

00:17:26 Non-conductor.

00:17:28 Distilled water does not conduct, pure distilled water does not conduct electricity.

00:17:39 Could have used little marks here, but I want to make a special point of the distilled water.

00:17:42 Here is water, which is normal tap water out of the faucet and the sink.

00:17:49 Well, the needle did wiggle a little bit.

00:17:52 There it is on zero.

00:17:54 When I break the contact, it's on about 20.

00:17:57 When I make the contact.

00:17:58 So tap water sort of can't make up its mind.

00:18:02 We're forced to say here, if anything, a very poor conductor.

00:18:06 But it did conduct some electricity.

00:18:11 Alcohol, a common beverage.

00:18:13 Some places, laboratory chemical.

00:18:16 Ethyl alcohol.

00:18:19 You just make sure that these are dry as far as the previous material is concerned.

00:18:25 Well, among the many properties that alcohol has, conductivity is not one of them.

00:18:30 Non-conductor.

00:18:38 And the last one.

00:18:43 Now we had here some salt, which is a non-conductor.

00:18:47 Some distilled water, which is a non-conductor.

00:18:51 Let's put a little bit of the salt into the distilled water just to mix the two.

00:18:54 See what happens.

00:18:56 Non-conductor together with a non-conductor should also make, well, at first guess, I suppose, a non-conductor.

00:19:04 Let me just use this rod and stir it here to make sure I have enough of the salt dissolved.

00:19:11 Salt plus distilled water, both of them non-conductors to begin with.

00:19:15 Whoops.

00:19:17 Good conductor.

00:19:20 Let's write that one down.

00:19:25 Salt water, then, conductor.

00:19:29 Actually, all the conductors we measured were good ones.

00:19:32 Well, here's a list then.

00:19:33 Each of these materials has had its conductivity measured, how it can conduct electricity.

00:19:40 So here we have the copper as a conductor, the salt water as a conductor, the tap water was a poor one,

00:19:47 and the rest were non-conductors.

00:19:52 We have now seen that some materials conduct electricity while others don't.

00:20:00 Now that we made this into a solution of salt water instead of distilled water,

00:20:04 maybe it's best to put it over here where it properly belongs.

00:20:09 Let's look further at this one interesting point.

00:20:12 That is, where two non-conductors were mixed together to make a conductor.

00:20:17 That is, the salt plus the distilled water.

00:20:20 To do this, I'll need this conductivity apparatus.

00:20:25 Take off the leads here.

00:20:32 And then move this whole business over to the next experiment.

00:20:43 There we go.

00:20:46 Put the light bulb out here where we can see it.

00:20:53 And let's see, we'll need distilled water, and that's right here.

00:20:57 Here is another material, acetic acid, an organic chemical which is present in vinegar.

00:21:04 Vinegar is actually a dilute solution of acetic acid in water.

00:21:09 I'll pour the acetic acid into this little beaker.

00:21:16 Notice that it touches the electrodes, the two copper electrodes.

00:21:20 Let's test to see if acetic acid is a conductor.

00:21:30 This says non-conductor.

00:21:32 Let's make sure and see that the apparatus is still alive since I moved it over.

00:21:36 I'll just short the leads, that is, touch one to the other.

00:21:39 Yeah, the apparatus works all right.

00:21:42 Acetic acid is a non-conductor.

00:21:46 We'll then go on our list as non-conductor.

00:21:50 Watch what happens as I add a little bit of water with stirring to this acetic acid.

00:21:59 Pour a little bit in.

00:22:01 Notice that a little bit of water causes a slight amount of conductivity.

00:22:05 It reads about 40 volts where it read zero before.

00:22:09 The light bulb is very dim.

00:22:13 A little more.

00:22:16 There it is, up to about 90 volts.

00:22:19 Light bulb a little brighter.

00:22:20 Light bulb a little brighter.

00:22:28 Still more water and let's add a lot.

00:22:34 There it is, up to about full voltage.

00:22:38 Acetic acid is a non-conductor when it's pure, nothing in it,

00:22:43 but as soon as you add water to it, it becomes a conductor.

00:22:47 This particular principle or this fact which was observed

00:22:53 was used by a very famous chemist by the name of Arrhenius, a Swedish chemist,

00:22:59 to explain, that is, Arrhenius observed this thing and then he explained it in the following way.

00:23:05 He said, well, when you take acetic acid or salt, sodium chloride, and add it to water,

00:23:10 what happens is that the molecules become ions.

00:23:15 Where you have molecules before, you now have ions.

00:23:20 The ions conduct electricity.

00:23:22 Now an ion is an atom or a group of atoms that carry an electrical charge

00:23:28 by virtue of either having lost an electron or so or more or gained an electron or more.

00:23:34 The salt, which is really a special case, I'll have a little more to say about that in just a moment,

00:23:38 the salt dissolved in water and generated a lot of sodium ions and chloride ions.

00:23:42 These conducted electricity.

00:23:45 The same for the acetic acid. Hydrogen ions and acetate ions in the case of the acetic acid.

00:23:50 The principle is called ionization.

00:23:52 Let's look further at ionization.

00:24:00 This next experiment will be a same type as the one we just saw, only with different chemicals.

00:24:07 I'll now transfer the leads from this beaker to this one.

00:24:16 Start with water this time.

00:24:19 We know that distilled water is a non-conductor according to our list,

00:24:23 and sure enough, it shows that it's a non-conductor.

00:24:29 Needle doesn't budge.

00:24:31 To this distilled water, I'll add a measured amount of a chemical, barium hydroxide.

00:24:38 See if you can guess what happens when barium hydroxide is added.

00:24:42 See if you can guess what happens when barium hydroxide is mixed with water.

00:24:58 Barium hydroxide then, in water solution, conducts electricity.

00:25:03 That means it ionizes.

00:25:05 It forms barium ions and a group of ions this time called hydroxyl ions,

00:25:12 ions which are a combination of oxygen and hydrogen.

00:25:16 By the way, the word ion means wanderer.

00:25:20 In a sense, this applies because the ions wander through the solution,

00:25:24 can move around, and in so doing, conduct electricity.

00:25:28 But the chemical definition is what I've said, charged particles.

00:25:32 Now, let's go on a step further.

00:25:34 This is now a conducting solution.

00:25:36 I will throw into this little flask some carbon dioxide solid.

00:25:45 If I handle these pieces quickly, they won't bother my fingers.

00:25:49 If I hold them too long, it'll sting a little bit.

00:25:52 This is extremely cold.

00:25:58 A little bit more.

00:26:01 There.

00:26:03 And I'll have a carbon dioxide generator.

00:26:08 Let's bubble some carbon dioxide into this solution of barium hydroxide in water.

00:26:13 The reading is now something like 118 volts.

00:26:18 Just under 120.

00:26:21 Notice the first thing that happens is that the solution of barium hydroxide turns milky.

00:26:36 There, it's bubbling a little faster, and the reading is dropping.

00:26:41 Way down.

00:26:43 It's now down to about 50 volts.

00:26:45 So the solution is now a poor conductor, where before it was a good conductor.

00:26:48 And, notice as we keep bubbling, it's coming up again.

00:26:54 Now, let's let it bubble while I explain what happened.

00:26:57 To begin with, the distilled water is a non-conductor.

00:27:00 Throwing in barium hydroxide formed ions.

00:27:03 This became a conductor.

00:27:04 As soon as I bubbled the carbon dioxide in, a new chemical was formed, barium carbonate.

00:27:10 As soon as I bubbled the carbon dioxide in, a new chemical was formed, barium carbonate,

00:27:15 which is insoluble in water, hence the solution is milky.

00:27:18 It also is a non-conductor.

00:27:21 So let the needle drop way down.

00:27:23 Keeping the carbon dioxide coming through caused the formation of yet the next chemical.

00:27:28 From barium carbonate, we got barium bicarbonate.

00:27:31 This is now soluble and a conductor.

00:27:34 So here is an interesting way to show the course of chemical reactions

00:27:37 by following the conductivity of the solution.

00:27:40 If we keep going, there it is.

00:27:41 It's almost up to 115, I guess now, 90, 110 volts.

00:27:45 It'll get up to 118 shortly.

00:27:47 Well, let's go on then and see what else we can learn about chemical changes

00:27:54 using this conductivity as a tool.

00:28:01 Let's just disconnect this here.

00:28:04 I must be careful to take these leads off one at a time.

00:28:08 Otherwise, I'm a good enough conductor to feel the effect.

00:28:14 The solution is actually becoming a little lighter,

00:28:16 indicating the formation of barium bicarbonate from the barium carbonate.

00:28:22 Now, I said that sodium chloride was a sort of a peculiar case.

00:28:26 It's true that the dry salt did not conduct electricity

00:28:30 and that when it went into water, it formed ions which did conduct the electricity.

00:28:34 I wasn't, I didn't exactly tell the whole story.

00:28:38 The salt, to begin with, is in the form of ions, even in the dry condition,

00:28:43 even as a dry salt.

00:28:44 The trouble is, the ions are not free to move around.

00:28:48 They cannot move and thus cannot carry the current.

00:28:51 So dry salt shows up as a non-conductor, even though it's in the form of ions.

00:28:55 When you throw it in the water, then the ions are free to move around

00:28:58 and can carry electrical current.

00:29:00 Let's look at an example of that kind of thing.

00:29:04 The leads that I have now are connected to a test tube

00:29:08 in which is placed some solid material, similar to sodium chloride.

00:29:12 Well, actually, this is a salt, potassium nitrate.

00:29:15 Notice what happens as I make the connection.

00:29:18 Non-conductor, dry potassium nitrate is a non-conductor.

00:29:23 Let's light the burner.

00:29:29 And get a good hot flame.

00:29:35 For this, I should wear my safety glasses in case the test tube decides to crack.

00:29:39 In case the test tube decides to crack.

00:29:57 The potassium nitrate is now beginning to melt around the edges of the test tube

00:30:01 where the flame is being applied.

00:30:10 Now melting over a great portion of the test tube.

00:30:13 The whole bottom is filled with what looks like water.

00:30:16 Actually, it's liquid potassium nitrate.

00:30:24 Anything on the meter yet? Nope, not yet.

00:30:40 There it is.

00:30:42 As soon as enough of the potassium nitrate has melted

00:30:45 to touch so that liquid potassium nitrate touches both leads,

00:30:49 we see that liquid potassium nitrate is a conductor.

00:30:52 So this is the answer about salt.

00:30:54 Sodium chloride or potassium nitrate.

00:30:56 This kind of salt.

00:30:57 They will conduct electricity when they're melted

00:30:59 because the ions can move around.

00:31:01 Well, let's see what we've learned.

00:31:03 We've shown the relationship

00:31:05 Well, let's see what we've learned.

00:31:07 We've shown the relationship

00:31:09 between chemistry and electricity

00:31:11 by using a photocell

00:31:13 and a fluorescent tube.

00:31:16 The photocell uses the same principle

00:31:19 as is present in photographic exposure meters.

00:31:23 We then had alternating current and direct current

00:31:26 write their signatures by using a chemical reaction.

00:31:29 The alternating current drew a dotted line

00:31:31 while the direct current drew a solid line.

00:31:33 We showed the conductivity of various materials.

00:31:36 We then pointed out that this conductivity

00:31:38 of salt in water

00:31:40 and of the molten potassium nitrate

00:31:45 was due to the use of ions.

00:31:47 Of ions being formed which conducted the electricity.

00:31:50 Thank you.

00:32:33 This is national educational television.