00:00:00 This film was made possible in part by the generous support of viewers like you.

00:00:10 This film was made possible in part by the generous support of viewers like you.

00:00:20 TEMPUS DINATESTU, a series of experiments designed to explain the mysteries of chemistry and the laws that govern it.

00:00:38 Produced by KQED San Francisco.

00:00:48 In cooperation with the California section of the American Chemical Society.

00:00:57 For the Educational Television and Radio Center.

00:01:03 And now let's go to our laboratory and meet Dr. Harry Sello.

00:01:08 Hello. In this talk, I'd like to show you some examples of how industry uses chemistry.

00:01:17 Here's the first one.

00:01:21 A flask into which I've placed two electrodes.

00:01:27 To start this experiment, I'll pour some of this test solution in, which we'll talk about after the experiment starts.

00:01:45 Replace the electrodes, and now hook them up to the batteries in a circuit.

00:01:54 To the two electrodes, I hook an induction coil.

00:02:02 The induction coil is merely a device to increase the voltage of the batteries, which is six volts, to a very high value in the thousands of volts at the electrodes.

00:02:23 Four batteries in series, one and a half volts each, to give the total of six volts.

00:02:41 The blue spark now is what can be seen at the tip of the electrodes in the flask.

00:02:48 The flask contains just a test solution and air.

00:02:55 Parts of the circuit again, the batteries, six volts, stepped up to many thousands of volts through the induction coil.

00:03:02 That results in a spark being thrown at the gap down in the flask.

00:03:07 Let's leave that, allow the spark to go on for some time, and come back to it in a few moments.

00:03:15 The next example of the way in which industry uses chemistry concerns the metallurgical industry.

00:03:24 That is, the industry in which metals are recovered from their ores.

00:03:31 As an example of a metal ore, I will use lead oxide.

00:03:40 It is common in nature to find the oxide of the metal in the presence of a lot of sand and clay and unwanted material.

00:03:49 The problem is how to separate the lead oxide, in this case, from the unwanted material in a way which will be not too expensive so it can be commercially applied.

00:04:02 I'll make up a mixture of the two, the lead oxide and the sand, which we will pretend is the way in which it's found in nature.

00:04:14 A little bit of lead oxide and some sand.

00:04:29 I've poured a little bit of sand now in with the lead oxide.

00:04:34 That induction coil is making too much noise. Let's see if we can silence it a bit.

00:04:39 I'll use this rubber pad as a cushion.

00:04:42 Better disconnect it first, otherwise the effect will be shocking.

00:04:51 Let's see if that makes it a little more quiet.

00:04:58 That's better.

00:05:07 I can't have anything standing in the way of the lecturer.

00:05:11 Well, here's the mixture, then, of the lead oxide and the sand. We'll just add a little bit more sand.

00:05:17 As it would occur in nature, lots of sand, a little bit of the lead oxide.

00:05:24 Mix these up thoroughly.

00:05:31 The problem, then, is to separate the two, the sand and the lead oxide.

00:05:38 This is the way in which it is actually done, with big commercial-scale equipment, but the principle is the same.

00:05:45 First, a little bit of oil.

00:05:56 And some water.

00:06:00 Water has been tinted to make it more visible.

00:06:07 Water, being heavier than the oil, goes to the bottom of the cylinder.

00:06:19 The oil and the water, of course, don't mix.

00:06:23 If I shake them, they will apparently mix.

00:06:26 Actually, they don't even after they're shaken.

00:06:28 What is formed now is called an emulsion.

00:06:31 That is, the little droplets of oil are surrounded by other droplets of water.

00:06:37 And if I let it stand while the two will separate, already the oil is beginning to float to the top.

00:06:46 To illustrate the separation process, then, I will throw the mixture of lead oxide and sand into this mixture of oil and water.

00:07:10 Shake again.

00:07:14 It's certainly a gooey-looking mess.

00:07:22 Thoroughly mix now all four materials together, oil, water, lead oxide, and sand.

00:07:31 Let's allow these to stand and see whether we can determine exactly what happened by the kind of separation that occurs.

00:07:38 In the meantime, I think we can take a look at the experiment that was started and see just how far it has progressed.

00:07:48 The arc now has been running for about, oh, four or five minutes.

00:07:54 The liquid in the flask has actually gotten a little darker.

00:07:59 It was water-clear to begin with.

00:08:02 It's slightly darkened.

00:08:05 I think it's best if we leave it stand just a little bit more and allow the reaction to go on even further.

00:08:12 Again, looking at the second process, already some separation is visible.

00:08:19 The upper layer from here to here is the oil layer.

00:08:24 The bottom layer is the water layer.

00:08:26 However, the upper layer now contains, in addition to the oil, the lead oxide.

00:08:34 While down at the bottom, starting right about here and below, there is a swedge of sand.

00:08:42 There is a little bit of both, a little bit of lead oxide, but mostly a suspension of sand in this water layer below the oil layer.

00:08:51 The majority, the great majority, of the lead oxide is up here.

00:08:55 So, by the addition of the mixture, lead oxide and sand, to the oil water, a separation has been effected.

00:09:05 The lead oxide floated to the top with the oil, and the sand sunk to the bottom.

00:09:11 This is the principle of the process known as flotation,

00:09:15 in which the lead ore, or the lead oxide, is floated away, caused to float away from the sand which settles to the bottom.

00:09:25 By the way, the sand which settles to the bottom is given a name in the metallurgical industry.

00:09:29 It's called gangue, G-A-N-G-U-E.

00:09:33 It can be drawn off the bottom out of tremendous tanks and thrown away,

00:09:38 while the lead oxide is skimmed off the top, separated from the oil by filtering, and the oil can be used and reused.

00:09:46 You see, this is important because normally little bits of lead oxide always get away in any kind of a process.

00:09:53 That's a waste. It would be good to recover every last trace that you can in order to have that process make more money.

00:10:00 This was devised as a way of getting at the last little bits of the oxide of the lead in this case, or it can be the oxide of any metal.

00:10:10 It is told, the story is told, that is, that this process was discovered by an old washerwoman

00:10:15 who was cleaning a pair of miner's overalls one day years ago,

00:10:19 and in the course of using a lot of suds on the greasy old overalls,

00:10:24 why, she noticed that the ore that was present in the overalls tended to float to the top with the suds,

00:10:30 while the water would collect the sand and fall to the bottom of the tub.

00:10:34 I don't know how true that story is, but that's at least the way I heard it.

00:10:37 Now let's take another look again at the arc process, which is the first example of how industry uses chemistry.

00:10:44 Again, the water has even, the test liquid, I should say, has even gotten more dark.

00:10:50 Let's disconnect this and see if we can tell what's happened.

00:11:01 Let's draw the electrodes.

00:11:09 Now,

00:11:11 slosh this around a little bit, so make sure that the liquid contacts the gas,

00:11:16 the air that's been exposed to the arc,

00:11:19 so as to ensure trapping all of any reacted products, any chemically reacted products that we may be making.

00:11:28 Now, for comparison, I'll pour a little bit of this liquid out in here, the test tube.

00:11:41 Stand that down there.

00:11:43 And compare it to the liquid that we started with.

00:11:55 One is quite a bit darker than the other.

00:12:01 The one under my thumb is amber, actually.

00:12:05 The other one is still water-cleared.

00:12:08 But, let's see if this indicator over here will even make the difference a little more pronounced.

00:12:19 Pour some into the water-clear sample, that is before we ran the arc.

00:12:26 There's a good amount here.

00:12:28 And some into the amber sample.

00:12:38 That's about an equal amount in both.

00:12:41 Stir them up together.

00:12:50 I'll shake this one. I don't want to color it with the glass stirring rod of the other.

00:12:58 There.

00:13:00 It's pretty obvious now that the one which was amber, by means of the indicator,

00:13:05 has been made quite a bit darker, while the first one has not changed at all.

00:13:11 Well, what is the process that was illustrated?

00:13:13 First, it's called the arc process.

00:13:16 It happens that, in the presence of an electric arc, in air, two things can happen, at least.

00:13:23 Nitrogen can combine with oxygen to form oxides of nitrogen.

00:13:27 This is one product.

00:13:29 This is not the one that we found.

00:13:31 This is a second reaction, in which oxygen combines with itself to form ozone.

00:13:36 Let's write this reaction on the board.

00:13:41 Oxygen, O2, in the presence of an electric arc, can go to ozone, which is O3.

00:13:50 In order to chemically balance this equation, we'll put a 3 here and a 2 here.

00:13:56 It's a sort of a way in which oxygen rearranges itself to form ozone.

00:14:01 The ozone is a useful product.

00:14:03 It is used as a bleach in the manufacture of fats and waxes.

00:14:07 It is used as a chemical reagent, a very strong oxidizing agent.

00:14:11 In the presence of an electric arc, this reaction takes place.

00:14:15 So from just the oxygen of the air, we can get a chemical product.

00:14:19 I've mentioned that the arc process is used to make nitrogen combine with oxygen.

00:14:23 This is really what we mean by the arc process.

00:14:26 The other way you should really say an arc process.

00:14:29 Nitrogen can combine with oxygen.

00:14:31 We know that this is a very important reaction, too.

00:14:35 We lead to fertilizer from this material and lots of compounds of nitrogen and oxygen.

00:14:40 Well, let's go on to our third example of industry uses chemistry

00:14:44 and see if we can illustrate yet another process.

00:14:48 For this, I need my induction coil again, so I'll have to go back and get it here.

00:14:53 I'll just put this back up so it doesn't fall.

00:15:10 Better take the pad in case it wants to make noise down here.

00:15:14 Now it would be very important to get the wires all unscrambled

00:15:18 because the results would be, as I say, quite striking, mostly on the lecture.

00:15:29 Now, in this process, I'm making use of a very simple apparatus,

00:15:35 an ordinary cardboard tube such as you might get from the

00:15:39 An ordinary cardboard tube such as you might get from the

00:15:43 roll of kitchen paper for drying your hands.

00:15:48 Nothing in the tube. It's all empty.

00:15:51 I can show that it's empty by running this glass rod right down the inside,

00:15:55 I hope, without breaking up anything, that wire.

00:15:58 Hollow.

00:16:01 Nothing up my sleeve.

00:16:04 This has a notch cut in the bottom, two toothpicks stuck through it,

00:16:08 and a piece of tin foil wrapped around several times.

00:16:12 Connecting the two toothpicks is a very thin copper wire.

00:16:25 Now I will connect up the induction coil,

00:16:29 one lead to the copper, thin copper wire,

00:16:33 which runs down the center of the cardboard tube,

00:16:36 and the second lead to the tin foil.

00:16:43 Light the burner. We'll need a little source of heat here.

00:16:48 Speaking about heat, it's getting quite warm already.

00:16:53 Now then.

00:16:56 Ah, I see one more step. I'll hook up one of the leads of the battery.

00:17:01 Again, this is a very thin copper wire.

00:17:05 I'll hook up one of the leads of the battery.

00:17:09 I'll hook up one of the leads of the battery.

00:17:13 I'll hook up one of the leads of the battery.

00:17:16 Again, this is the same setup, six volts from four batteries in series.

00:17:21 The second lead I'll connect just when we're ready.

00:17:25 Now then. Here's a little bit of phosphorus,

00:17:29 which I set on fire in the burner.

00:17:33 Whoops, set everything else on fire too. We'll just let that burn out.

00:17:38 If I put the phosphorus in the tube, I set up quite a smoke screen.

00:17:42 Watch what happens when I connect the coil.

00:17:45 Well, it diminishes a little bit, not much.

00:17:49 One thing that can be tried here is to reverse the electrodes

00:17:53 to see whether this has a stronger effect.

00:17:56 It should be a little bit more obvious than this.

00:17:59 I'll just reverse the electrodes from the induction coil.

00:18:03 Give it one more try. Test it out here. Right.

00:18:08 Ah, I think it's because the wire down the center isn't right down the center.

00:18:13 Let's try it now.

00:18:15 One more shot of phosphorus.

00:18:17 I hope the lecturer doesn't get overcome by this.

00:18:24 Now, put some in this. There it is.

00:18:28 Disconnected. Smoke. Connected. No smoke.

00:18:31 Ah, that's a good one. Disconnected. Smoke. Connected. No smoke.

00:18:35 All it needed was a reversing.

00:18:38 Let's explain what happened on the blackboard.

00:18:41 Let this phosphorus burn its way out.

00:18:46 The control precipitator looks like this.

00:18:51 I've already used the term which defines the process.

00:18:54 I'll get back to that in just a moment.

00:18:56 Here's the cardboard tube.

00:18:59 It has two supports across the top, which are the toothpicks, actually, in this case.

00:19:04 Around the outside, there is wrapped the foil.

00:19:12 A wire is suspended from here to here and actually sticks out of the top.

00:19:18 Here is the notched portion.

00:19:22 Now, I put the burning phosphorus in here.

00:19:25 That gave off the smoke composed of phosphorus oxide.

00:19:28 This is really a collection of particles.

00:19:32 As these particles come up, they get charged in this electrical field,

00:19:36 which is imposed by one lead coming to the tin foil and the other lead coming to the wire.

00:19:42 As the particles come up, they get charged.

00:19:45 That is electrical in nature.

00:19:48 They become electrically charged simply.

00:19:50 Then, as they go further up the field, they either go over to the foil or on the wire.

00:19:55 That is, they collect on both surfaces,

00:19:59 depending on which one is negative when the particles are positive and so forth.

00:20:04 This results in collection of the particles.

00:20:06 They then, if this is kept up a long time, would fall to the bottom,

00:20:09 and we could actually recover phosphorus oxide.

00:20:12 This was invented by an engineer by the name of Cottrell.

00:20:15 It's a precipitation method, so we can call the process a Cottrell precipitation.

00:20:19 The apparatus is a Cottrell precipitator.

00:20:22 It was first used in California, actually, in about 1910 or thereabouts.

00:20:29 It is a commercial process used for the recovery of many dusts and smokes.

00:20:33 Let's go on and look at the other ways in which industry uses chemistry.

00:20:40 It seems that we are concerned mostly here with processes involving the use of electrical energy.

00:20:46 Here is another one.

00:20:49 In this beaker, I'll pour some copper sulfate solution.

00:21:07 There is a strip of copper as one of the electrodes immersed in the copper sulfate solution.

00:21:15 The other electrode is a small piece of lead bent in the form of a bell.

00:21:21 I'll immerse that so that about half of it is covered by the copper sulfate solution.

00:21:29 Then, there are two batteries in series this time, that's a total of three volts,

00:21:33 an ammeter to show how much current passes through the circuit.

00:21:37 Let's now make the connection.

00:21:40 Let's see, we actually want...

00:21:49 ...the connection so that the lead is the negative terminal.

00:21:53 That's thought to be here, this one, so...

00:21:59 ...and positive terminal over to the copper.

00:22:06 Let's see if we can get this so we don't interfere with the ammeter.

00:22:11 Now, watch what happens on the ammeter as soon as I complete the circuit.

00:22:15 There.

00:22:16 The passage of electricity is indicated by the fact that it reads about just under a half an amp,

00:22:22 about 0.44 amperes, is now going through the little cell, or this little circuit.

00:22:30 Now, notice that I can adjust the current, or affect the current,

00:22:34 by moving the little lead metal closer or further from the copper.

00:22:38 If I move it closer, the current goes up.

00:22:41 So, it's now up to six-tenths of an ampere.

00:22:45 If I move it further away, the current goes down.

00:22:48 There it is, as far away as we can move it over to the side of the beaker,

00:22:51 and it's down to just about three-tenths of an amp.

00:22:54 Let's move it over to the high value so that the process will go a little faster.

00:23:01 Now, while this is moving along, let's go on and look at the next experiments,

00:23:06 and then we can come back, the next experiment, rather,

00:23:08 and come back and look at this.

00:23:13 Here is also a commercial process in use at the present time.

00:23:19 A simple example of it.

00:23:22 Here's a sample of seawater.

00:23:24 I'll pour into this beaker.

00:23:26 Now, it is known that seawater contains many valuable minerals.

00:23:31 One of them, or many valuable elements, I should say, one of them is iodine.

00:23:39 I'll pour into this a bleach, actually a hypochlorite solid.

00:23:46 In this case, it's calcium hypochlorite.

00:23:49 I'll pour that into the beaker.

00:23:55 And it becomes quite dark.

00:23:58 Now, I'll get the stirring rod here.

00:24:02 Stir this up.

00:24:06 The bleach acts so as to liberate the iodine from the seawater.

00:24:12 In the seawater, iodine is present as iodide, potassium iodide, usually.

00:24:17 Some sodium iodide as well.

00:24:20 When sodium or potassium iodide reacts with calcium hypochlorite,

00:24:25 why, iodine is liberated.

00:24:27 That is the reason for the dark brown color,

00:24:30 which can be seen by using it holding up a light against the light background.

00:24:34 How do you recover the iodine, then, once it's been liberated?

00:24:38 This is where the process comes in.

00:24:41 I'll pour the iodine solution into this separatory funnel,

00:24:47 pear-shaped glass equipment.

00:24:55 That's about enough to show the...

00:25:01 Chemists always say that's about enough, and then add a little bit more.

00:25:05 Here is the material which we will make use of.

00:25:08 This is carbon tetrachloride.

00:25:10 This is carbon tetrachloride.

00:25:11 Notice that it is water-clear, no color.

00:25:13 It's just the color of water, let's say.

00:25:18 I'll pour this also in here.

00:25:20 The carbon tetrachloride, being heavier than water, more dense than water,

00:25:24 will go to the bottom in the separatory funnel.

00:25:30 Now, the carbon tetrachloride, though it is water-clear here,

00:25:34 is now coming out darkened in the bottom.

00:25:38 This is actually a purple color, the typical color of iodine.

00:25:42 Already, some of the process has taken effect.

00:25:45 That is, the carbon tetrachloride has removed some iodine from the upper layer.

00:25:49 Let's just help this along by shaking it.

00:25:55 Now, in shaking this way, I'm causing the carbon tetrachloride

00:25:59 to come in close contact with the water containing the iodine.

00:26:04 When it does this, the carbon tetrachloride extracts the iodine from the water.

00:26:09 That's the reason the carbon tet becomes darkened and falls to the bottom,

00:26:15 so that the carbon tet extracts the iodine.

00:26:18 This process, then, is extraction.

00:26:20 All we have to do now is to separate the carbon tet,

00:26:25 carbon tetrachloride, from the water layer,

00:26:29 then take it into a special separate step

00:26:32 where we evaporate the carbon tetrachloride and leave behind the iodine.

00:26:36 We will not perform that step here.

00:26:38 We will show only that we can remove it into the carbon tet.

00:26:42 Let's take a look now at our plating experiment.

00:26:48 Now, if I just pull this out, you can see the current drops off.

00:26:53 But I will disconnect it, actually.

00:26:55 Let's take a look at the little bell.

00:26:58 There.

00:27:00 The bottom half of the bell that was stuck in the copper sulfate solution

00:27:04 is now covered with a coppery, is now a coppery color, covered with copper.

00:27:09 The top half, which was not immersed, still has the gray color characteristic of lead.

00:27:13 So we have illustrated the process here of plating by the means of using electricity, electroplating.

00:27:19 In this case, we covered lead with copper.

00:27:21 This is a very common process in industry.

00:27:25 Let's review the processes which were illustrated here in this talk on industry uses chemistry.

00:27:32 The first was the arc process.

00:27:34 Here, we cause oxygen to react with itself to form ozone.

00:27:38 The presence of ozone was detected by the liquid present in the flask, which was potassium iodide.

00:27:44 This changed to iodine.

00:27:46 In turn, this was then indicated by the starch.

00:27:51 The second process was flotation, in which lead oxide was separated from sand.

00:27:56 The third was catrell precipitation, where a smoke was separated from the air.

00:28:03 The fourth was electroplating.

00:28:05 Here, we plated a piece of metal with copper, illustrating a common industrial process.

00:28:12 And finally, the last process was extraction.

00:28:15 There, we recovered iodine from seawater.

00:28:19 Thank you.

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