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 24th, 1955, on KQED Channel 9, the educational station for the San Francisco Bay Area.

00:00:24 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.

00:00:39 These were designed to illustrate basic, simple chemical principles.

00:00:44 The purpose was to stimulate an interest in chemistry by teenage students and by adults.

00:00:52 The talks and experiments had to be entertaining, educational, and simple.

00:00:58 Spontaneity and liveliness were key to the approach.

00:01:02 All the experiments used in the shows were designed and constructed by members of the California section of the American Chemical Society.

00:01:11 The participants were employed by the Shell Development Company, Emeryville, and by Chevron Research, Richmond.

00:01:19 A grant of $52,000 from the Ford Foundation and National Educational Television permitted the filming of the first 24 shows of the series.

00:01:30 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.

00:01:44 We four constitute the core of the present committee.

00:01:49 The series was extremely popular then with KQED viewers of all ages.

00:01:57 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.

00:02:17 We believe in chemistry as a second language.

00:02:22 While basic principles have not changed, practices have.

00:02:27 Forty-five years ago, such simple chemical demonstrations were not treated with the degree of safety considerations that they are today.

00:02:36 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.

00:02:51 The principle of safety first would be explicitly present as part and parcel of a modern Tempest in a test tube.

00:03:21 Tempest in a test tube.

00:03:50 A series of experiments designed to explain the mysteries of chemistry and the laws that govern it.

00:03:58 Produced by KQED San Francisco.

00:04:06 In cooperation with the California section of the American Chemical Society.

00:04:16 For the Educational Television and Radio Center.

00:04:22 And now let's go to our laboratory and meet Dr. Harry Sello.

00:04:28 Hello.

00:04:30 In this talk, I'd like to invade the household and examine some of the chemistry of the kitchen.

00:04:36 Household chemistry.

00:04:42 The common household item, water.

00:04:57 Some of you may not recognize the equipment as being standard kitchen-type equipment, but we've sort of modified our laboratory kitchen, so as to speak.

00:05:06 Here's some sulfur, which, though not a household item, will illustrate the principle here.

00:05:12 I think we need just a little more water.

00:05:18 There.

00:05:24 The question this experiment would like to answer is, is water wet?

00:05:42 Sulfur is a solid.

00:05:45 It's certainly more dense than water.

00:05:49 So that in water, sulfur should sink, yet it floats.

00:05:55 Let's see if we can make it sink.

00:06:00 I will add a little bit of a mysterious chemical.

00:06:11 When the sulfur sinks, it is now being wet by the water, and being more dense than water, sank to the bottom.

00:06:20 What is this mysterious chemical?

00:06:23 This chemical is what we call a detergent.

00:06:29 The dictionary meaning of the word detergent is a cleansing agent.

00:06:35 This meaning, however, is not the one which is commonly used in the scientific laboratories or in commercial practice.

00:06:43 Before drawing a distinction between the various terms to be used, the commercial terms versus the dictionary meaning, let's go on and look at the next experiment.

00:06:54 I have a glass plate which has been previously artificially dirtied, which means waxed.

00:07:02 Most dirt is rather oily or greasy.

00:07:06 So that by waxing the glass plate, we've achieved the same effect.

00:07:09 I'll put some colored water on the plate.

00:07:12 A few droplets.

00:07:14 Here.

00:07:16 And over here.

00:07:21 Notice how the water droplets stay as droplets.

00:07:25 They do not flow into one another.

00:07:27 They're separated in most cases.

00:07:32 But if I wet my finger and rub it on the bar of soap here, watch what happens.

00:07:51 If I do the same with the finger that has not touched soap, notice that it's entirely different.

00:08:00 The droplets still tend to stay separated, will not flow together.

00:08:04 But the area which is treated with the soap, in that area the water has spread out as a film.

00:08:11 This has been the action of the soap.

00:08:14 Exactly what happened now in these two experiments?

00:08:17 Two chemicals have been illustrated, a detergent and a soap.

00:08:22 Now as I say, the dictionary meaning for detergent is a cleansing agent.

00:08:26 But you see, that would apply to both materials, what I call the detergent and what I call the soap.

00:08:33 However, let's forget the dictionary meaning.

00:08:35 This does not apply in the case here.

00:08:37 The real meaning, which is the usage, is that a soap is different than a detergent.

00:08:45 Let's take a look and see what I mean by the difference between a detergent and a soap.

00:08:51 A soap is defined as a long chain, fatty acid, sodium salt.

00:08:59 Well, this is rather complicated, but it looks something like this if you work the diagram.

00:09:04 A long wiggly part of a molecule, plus an end, which I'll designate by a little oval.

00:09:12 And put N-A here for sodium, sometimes K for potassium.

00:09:19 This part is composed of carbon and hydrogen.

00:09:26 This part contains carbon, hydrogen, and oxygen, in which the hydrogen has been replaced by potassium or sodium.

00:09:36 You see, this part we call a fatty acid.

00:09:38 When you add sodium or potassium, you make the sodium or potassium salt of that fatty acid.

00:09:43 This is a soap.

00:09:45 A detergent is almost the same.

00:09:48 It has a long chain portion composed of carbon and hydrogen.

00:09:53 At this end, it has also an end which will contain some sodium, usually.

00:10:02 Here, however, the carbon and oxygen are in different proportions than they are here.

00:10:08 This is an acid.

00:10:09 This is an alcohol.

00:10:11 This, you see, is a natural product.

00:10:13 The fatty acid is a natural product, whereas the long chain alcohol is a synthetic product.

00:10:21 This end of the molecule is soluble in water.

00:10:26 I'll put a circle around it for water droplet.

00:10:32 Same for the soap.

00:10:34 If they're almost alike, then what is the difference?

00:10:38 The difference is that a detergent is a much more efficient molecule in doing its cleaning action than is a soap.

00:10:46 That means now we've also defined one of the things that a detergent is used for, for cleaning.

00:10:52 Let's look further and see what's meant by that.

00:10:56 By the way, I would like to point out that what made the sulfur sink was the fact that the sulfur particles were coated by the detergent which I used.

00:11:06 Coating the sulfur particles broke down the surface tension of the water.

00:11:11 It has broke this invisible skin that's present on the surface of water and caused the sulfur to fall right through and get wet.

00:11:19 Without the detergent, this could not happen.

00:11:23 Let's look then at the cleaning action of a detergent or a soap.

00:11:27 Now remember, the two words are different.

00:11:30 That is, the two materials are different, but they can both be used for cleaning, the detergent being the more efficient one.

00:11:42 Put a little water into both of these cylinders.

00:11:54 And to pretend we have dirt, let's use a little bit of carbon.

00:12:01 Most dirts are carbonaceous in their form.

00:12:08 Let's get our stopper straightened out first. There we go.

00:12:12 Most dirts are carbonaceous, consist largely of carbon, so this will be a pretty good substitute.

00:12:19 Put a little bit in both cylinders.

00:12:26 And a little in here.

00:12:32 Well, it looks like this isn't going to be dark enough. Let's just add a little bit more to make sure we get this water good and dirty.

00:12:40 Now, of course, I shake these.

00:12:46 The water and the dirt don't mix very well, but I can certainly suspend the carbon a little bit.

00:12:53 Yet, it will still fall to the bottom.

00:12:57 Already beginning to separate out.

00:12:59 To even up this look, let's add a little bit more water.

00:13:02 I say I have more water in one than the other.

00:13:05 I'm certainly having a time trying to fit stoppers in here, too many of them.

00:13:09 Now then, let's leave one alone and to the other add some detergent.

00:13:16 This is a water solution of a detergent of the type I have described up there on the blackboard.

00:13:26 Shake this.

00:13:28 Note the amount of detergent.

00:13:32 Shake this.

00:13:34 Note the formation of the suds.

00:13:36 This is typical of many detergents.

00:13:38 The suds form because the surface tension of water is so much lowered that little bubbles can form.

00:13:45 Now, let's examine this with the aid of a light behind it.

00:13:52 This is pretty murky, at least at the start.

00:13:56 Pretty even throughout.

00:13:58 Awfully hard to see the light through it at any rate.

00:14:01 This one is still kind of murky, but I see that the particles are still beginning to settle out.

00:14:08 Let's leave this, stand for a while, and see what happens, whether the particles settle out in both.

00:14:17 We are now talking about the cleaning action of the detergent.

00:14:20 By this experiment, we'll see shortly, it's already started,

00:14:24 that one of the ways in which a detergent cleans is to coat dirt particles,

00:14:29 to keep them suspended so that they don't collect in a pocket

00:14:32 and fall down in the bottom of a washing basin or a sink

00:14:35 or in the bottom of a container that you're trying to clean.

00:14:38 By keeping these particles suspended, they may be washed away, rinsed away,

00:14:41 which would not be the case if the detergent were absent.

00:14:45 But besides the cleaning agent, the detergent, or the soap that's needed,

00:14:49 the water part of the cleaning is important.

00:14:53 Let's see how that works.

00:14:57 Here is some ordinary, well, distilled water, which means soft water.

00:15:03 I'll pour some of that in here.

00:15:09 In these others, I will add what we call hard water.

00:15:15 It looks about as soft as soft water, but actually we call it hard water.

00:15:19 The reason for that will be explained in a moment.

00:15:26 Don't need exactly the same amount, but just about will do.

00:15:33 Now, the first one, soft water.

00:15:36 The next three, hard water.

00:15:39 Here is an ordinary, a solution of an ordinary hand soap,

00:15:43 a mild soap which is used to wash hands, face, sometimes clothing.

00:15:48 Here's what happens with the hand soap and the soft water.

00:15:59 Plenty of suds.

00:16:01 The suds indicate that the soap is exerting its action.

00:16:05 Doesn't necessarily mean that a good cleaning job can be done.

00:16:08 You don't need suds for a good cleaning job with some detergents,

00:16:12 but it's an indicator of the fact that the soap

00:16:16 acts to break down the surface tension of the water.

00:16:19 Let's look at the effect of soap on the hard water.

00:16:25 We got most of the soap in there.

00:16:41 Look at the difference in the amount of suds.

00:16:44 I use my soap only in one case, soft water, the other case, hard water.

00:16:48 In fact, the suds practically break up right after I shake it.

00:16:53 But there is scattered throughout the water a white particles,

00:16:59 a collection of white particles, that is,

00:17:01 indicating that the soap has gone into an insoluble form.

00:17:06 This is why hard water is called hard.

00:17:09 It forms insoluble material.

00:17:12 What it does is that the thing that makes water hard

00:17:14 is the presence of the minerals calcium or magnesium.

00:17:18 Calcium or magnesium react with soap to form an insoluble precipitate.

00:17:24 Precipitate means something which can settle to the bottom.

00:17:27 Precipitate.

00:17:28 This, you see, cannot do any good cleaning action

00:17:31 because the soap has been used up in forming the precipitate.

00:17:34 So it's important when you have a soap or a detergent,

00:17:37 well, I'll take out the detergent.

00:17:38 It's important when you're using a soap

00:17:40 to make sure that the water isn't excessively hard.

00:17:43 In places like central Missouri,

00:17:45 that I've had some personal experience with,

00:17:47 the water is unusually hard,

00:17:49 and there has to be treated before it can be used.

00:17:51 But let's look further at what treatment can do.

00:17:55 Well, supposing we're concerned with the problem of hard water

00:17:57 and have only that to deal with.

00:17:59 How do we get it soft?

00:18:02 One way is to add a water softening agent.

00:18:06 Such an agent is washing soda,

00:18:10 which is a common household material.

00:18:12 Here's a little washing soda.

00:18:13 The chemist will recognize this as sodium carbonate.

00:18:17 Let's dump some washing soda in the hard water.

00:18:26 Use a good bit because the water is excessively hard at this point.

00:18:32 Shake it up.

00:18:35 No suds, of course, since no soap or detergent has been added.

00:18:38 But you see a milky precipitate has formed.

00:18:41 This shows the action of the sodium carbonate.

00:18:43 By forming the precipitate first,

00:18:45 the calcium or the magnesium are taken out of the field of action.

00:18:49 Now let's add some soap

00:18:51 and see whether we have softened the water at all.

00:19:02 Well, we've softened it some.

00:19:05 There are some suds, not much different than this.

00:19:11 It would take a little bit more of sodium carbonate

00:19:14 and would improve just a little bit, but not much.

00:19:16 Well, this is a partial help.

00:19:18 But what's the real best way to handle washing in hard water?

00:19:21 The answer is to use a detergent.

00:19:23 Here is my detergent solution.

00:19:26 Let's pour that into the hard water.

00:19:29 Let's pour that into the hard water and see what happens there.

00:19:41 Suds form.

00:19:43 The detergent doesn't care whether the water is soft or hard.

00:19:46 Calcium or magnesium do not affect the detergent molecule.

00:19:49 So, soft water will work well with a soap.

00:19:53 But with hard water, you either,

00:19:55 because of the solids that are formed due to the calcium or magnesium,

00:19:58 you have to either use sodium carbonate, washing soda that is,

00:20:01 or use a detergent in order to get the cleaning action.

00:20:04 In parts of the country where hard water is a real problem,

00:20:08 it isn't practical to use large quantities of washing soda,

00:20:12 that is, sodium carbonate.

00:20:14 What is used are commercial softeners.

00:20:18 Here is a laboratory model of a commercial water softener.

00:20:21 Let's see if we can demonstrate how it works.

00:20:25 We'll test the hard water first, as we did before.

00:20:28 Here's a sample of the hard water.

00:20:30 Now, this water is called hard water, as I explained,

00:20:33 because it contains magnesium ions,

00:20:36 that is, charged magnesium atoms.

00:20:41 To this, we'll add a little soap to this hard water.

00:20:46 Shake, and very few suds form.

00:20:50 In fact, the suds are beginning to disappear.

00:20:53 Remember, we use the suds as an indication of whether the soap

00:20:56 would really cause the surface tension of the water to decrease.

00:21:00 There is now a precipitate forming in this test tube.

00:21:04 Let's set this one aside.

00:21:08 And, see how it works.

00:21:11 Okay.

00:21:14 And, see if we can improve the water.

00:21:20 Just adjust this here a bit.

00:21:24 I'll pour some of the same hard water I just tested

00:21:27 into this solid material in the cylinder.

00:21:37 And, it percolates through almost immediately.

00:21:40 The liquid goes down around through the particles of the bed,

00:21:45 of the solid bed.

00:21:49 Let's now collect a sample of this water

00:21:52 and see if we've improved the water any by our soap test.

00:22:08 It comes through rather slowly because these are very fine particles,

00:22:11 and the water can only percolate through rather slowly.

00:22:16 I think that's enough for a test.

00:22:20 Add our soap solution.

00:22:27 A little bit of it is necessary.

00:22:30 And, there is a layer of suds.

00:22:37 Very little solid material.

00:22:39 In fact, it's very hard to see.

00:22:41 Compare this to this solid material in the hard water

00:22:46 where the solid material is separated completely from the water itself.

00:22:51 Here, it's pretty uniform throughout, and a head of suds above it.

00:22:57 Well, this material in the water softener is called an ion exchanger.

00:23:04 Let's write that on the board.

00:23:15 X, change, er.

00:23:20 The exchange is performed in the following way.

00:23:24 To begin with, there are sodium ions on the bed of this material,

00:23:29 which is an organic compound, a solid compound.

00:23:32 When you pour the hard water through, the water that contains the magnesium ions,

00:23:37 the sodium and magnesium exchange places.

00:23:41 The sodium stays behind.

00:23:43 The magnesium ions go through.

00:23:45 I've got that turned around already.

00:23:47 My ion exchanger works a little bit differently.

00:23:49 I should have reversed myself.

00:23:50 The magnesium ions stay on the bed.

00:23:52 They're the ones we don't want.

00:23:54 The sodium, which was there first, goes through.

00:23:57 Sodium ions in the water allow the soap to form suds.

00:24:01 That is the soft water.

00:24:03 When the bed is all spent, used up, that is, it's all full of magnesium ions,

00:24:08 we pour some salt solution through, and that exchanges in reverse.

00:24:12 The sodium goes back on.

00:24:14 The magnesium gets washed through.

00:24:17 Well, let's go on and look at the next experiment involved in this talk on household chemistry.

00:24:25 Another problem with the use of detergents and soaps,

00:24:28 as well as with many materials in the household kitchen,

00:24:32 is the alkalinity of the material.

00:24:36 How alkaline or how basic are most things that are used in the kitchen?

00:24:41 Well, here is a sample of six materials commonly used in the kitchen.

00:24:44 Let's take a look and see if we can decide how alkaline they are

00:24:48 and maybe whether this is bad or good.

00:24:52 The six materials are three kinds of soap.

00:24:56 Well, I have to correct myself in terms of the definition given before.

00:25:00 There is one soap called mild soap.

00:25:03 There are two detergents.

00:25:05 One is what has been called commercially a cold water soap.

00:25:09 The other is a regular detergent.

00:25:13 Let's add some solvent, some water, to all of these.

00:25:18 And in the first one I have an empty beaker.

00:25:20 We'll just use that as sort of a blank test.

00:25:23 Here, this takes care of the soaps and the detergents.

00:25:26 Now we come to other household materials, baking soda, washing soda,

00:25:30 and this one on the end, which is already in the form of a solution.

00:25:34 Well, I can add a little water to it.

00:25:36 It's lye, sodium hydroxide, the chemist calls it.

00:25:39 Now we can quickly decide whether these are alkaline or not.

00:25:45 Here's an indicator which will turn dark in the presence of alkali.

00:25:50 I'll put some into the water itself.

00:25:52 Well, that didn't do anything because the water is neutral.

00:25:55 It's neither alkaline nor acid.

00:25:58 Here is what we call a cold water soap.

00:26:01 This soap has been advertised commercially as being good for woolen products.

00:26:05 Let's see what it does on this test.

00:26:08 No color change.

00:26:11 Let's go on to the next one, the mild soap.

00:26:15 There is a slight change in color.

00:26:19 I should stir this one. I didn't do it yet.

00:26:22 No color on the cold water soap.

00:26:24 The mild soap has a slight change.

00:26:27 It's just a little bit dark.

00:26:29 Here is the soapless detergent, similar to the type we illustrated early in the talk.

00:26:34 There is a profound color change, very dark, indicating it's quite alkaline.

00:26:40 Most commercial detergents are quite alkaline.

00:26:43 This cold water soap happens to be one of the few that's not.

00:26:47 Here's baking soda.

00:26:50 Stir that up a little bit.

00:26:56 Add a little bit more indicator. We ran out here.

00:27:01 This does not change.

00:27:04 It's very slight, can hardly be seen in the presence of this indicator.

00:27:08 Although baking soda is slightly, slightly alkaline, this will not pick it up.

00:27:13 Here is some washing soda.

00:27:18 Really dark color, just about the same color as this detergent.

00:27:22 The reason is that this detergent happens to contain a lot of washing soda in it that's sold that way.

00:27:29 It's supposed to improve the washing action.

00:27:32 Here is lye, or sodium hydroxide.

00:27:36 Of course, that's quite alkaline.

00:27:39 Well, is alkalinity bad in materials?

00:27:43 I wouldn't say it's exactly bad, but one should certainly be careful.

00:27:46 For example, you wouldn't want a strongly alkaline material to wash your hands and your face.

00:27:50 It would irritate your skin, get in your eyes.

00:27:52 But there's another reason why an alkaline material is undesirable.

00:27:56 Here is a solution of the same sodium hydroxide mixture that I had here that we tested the alkalinity of.

00:28:04 The one which showed it to be very strongly alkaline.

00:28:06 It's been boiling here for some time, simmering over the burner.

00:28:13 A little superheated is the reason it boils up when I stir it.

00:28:17 Into the solution I will put two swatches of cloth.

00:28:22 One is ordinary white cotton.

00:28:25 The other is a piece of wool, pure wool, cashmere.

00:28:30 Let's drop them both in there and see what happens.

00:28:35 Now, while this is stewing along here, let's look back and see just what we learned about household chemistry.

00:28:43 First, we defined a soap and a detergent.

00:28:48 Two different things.

00:28:50 Both exert a cleaning action and reduce the surface tension of water so that they can exert this cleaning action.

00:28:59 A detergent is a synthetic material made in laboratories.

00:29:04 It's a sodium salt, usually, not necessarily.

00:29:08 There are other kinds of detergents.

00:29:10 It's a sodium salt of a long chain fatty alcohol, the way the organic chemist would describe it.

00:29:15 A soap is a sodium or potassium salt of a long chain fatty acid.

00:29:21 The real distinction is in the one case fatty alcohol, in the other case fatty acid.

00:29:27 Now, there are many kinds of detergents.

00:29:29 I just described one of them.

00:29:32 We saw how they, the soap and the detergent, exert their cleaning action, particularly the detergent.

00:29:39 Here was the suspension of charcoal and water.

00:29:42 Here's the charcoal and water plus the detergent.

00:29:45 Let's take a look and see how they look now after they've been standing here for some time.

00:29:52 The one with the charcoal, water, and detergent is still quite murky.

00:29:59 The light barely gets through, if at all, indicating that the dirt, the charcoal, is still suspended.

00:30:06 The other one, the light can shine through quite readily,

00:30:11 indicating that in the absence of the detergent, charcoal and water will just fall to the bottom.

00:30:18 So this was one of the ways in which a soap or detergent cleans.

00:30:22 The particles of dirt are coated, kept in suspension, then they can be rinsed away.

00:30:28 We then saw how it is important to have soft water, if you can, to do washing and cleaning

00:30:36 because soap in hard water forms an insoluble precipitate.

00:30:40 Water is hard because it contains ions such as calcium or magnesium dissolved in it.

00:30:47 Water can be softened by using an ion exchanger, which was demonstrated.

00:30:52 Finally, we looked at the alkalinity of various materials which are used in the kitchen, in the household.

00:31:00 There was a whole string of them, a soap, two detergents, various other materials.

00:31:06 To demonstrate that alkalinity may be bad if it's excessive,

00:31:11 I threw a piece of cotton and wool into this solution of sodium hydroxide, which is quite alkaline,

00:31:18 and, well, it's easy to see, there's no wool left.

00:31:22 All that is left is the piece of white cotton.

00:31:26 So to answer the question, is sodium hydroxide or strongly alkaline material good for wool cloth,

00:31:33 the answer is definitely and positively no.

00:31:36 To wash wool, you must use cool water and a mild soap, something like that cold water soap that we demonstrated.

00:31:44 Thank you.

00:31:45 The End

00:32:15 This is national educational television.