* [upbeat electronic music]
- Audience: Woot! Woot! Woot!
- Hello, everyone,
and welcome to this very special 48th anniversary
of this very special program.
Number 48
to celebrate the joy of science
and to celebrate the use of science in society.
Are you ready to learn? [cheering]
Are you ready to have some fun? [more cheering]
Well, let's get started then.
[buzzing, then a loud boom]
[surprised exclaims] - Whoa! - Child: What was that for?
- Bassam: This was--
Still going. You hear it?
This was an uncontrolled combustion reaction
very different than this controlled combustion reaction
of the candle.
What I had in here is a little bit of alcohol
and it vaporized.
And there are two screws on the side.
And there was a cork that was ejected
when the spark coming from what we call a Tesla coil
ignited the vapor.
I want to show you in this bottle right here,
which doesn't have any alcohol in it, no cork in it--
I'm just going to show you
how the spark jumps across the gap
that separates the two screws.
So let's do this in the dark.
See it in the dark, maybe? Better.
Now you see it, now you don't.
All right, lights back up again, please.
So it is the ignition of the vapor
that caused the chemical energy in the alcohol
to change into mechanical energy
and the cork was ejected.
In my lab, we always obey the safety rules
and that's why you see I have my goggles on
and we have a fire extinguisher ready to be used
just in case something goes out of control.
We're not planning on anything going out of control.
We just have it as a safety precaution.
I'm going to put it on the side here
where you and I know where it is
in case it has to be used.
And that's another thing that we do in my lab
is that we repeat the experiment.
So I'm going to repeat this experiment right here.
Are you ready for this?
[cheering]
Give me a countdown: three...
- Audience: Two, one. [buzzing]
[chemical explodes]
[oohs and ahs] [applause]
[expressing anticipation]
- Let's have a louder countdown: three...
[buzzing] - Audience: Three, two, one.
[chemical explodes]
[oohs and ahs] [applause]
What I'd like to do now is an experiment
where I take a small amount of a solid
called sodium acetate.
I put it in this dish
in two locations.
And then what I want to do is
take a clear and colorless liquid.
It's actually a solution,
a supersaturated solution of sodium acetate.
And what I'm going to do
is pour the liquid on top of the crystals,
and now we'll see what happens.
You can see that the liquid is turning into a solid.
That's because the crystals of sodium acetate were seeding
and causing the...
sodium acetate to come out a liquid.
Let's see if I can steady my hand
and make this go taller and taller.
How tall do you think I can make this go?
[laughter]
- Audience: More!
- Bassam: More? - Audience: Yeah.
- Ok, keep going.
Keep going.
[excited chatter in audience]
Pretty good, wouldn't you say?
- Audience: Yeah. [boisterous cheers and applause]
- Let me push my luck a little bit
and do what we always do in science,
repeat the experiment. [laughter]
So let's see if my left hand
can produce the same effect.
I can report to you that I feel some heat
coming from the solid, which tells me that
when the supersaturated solution of sodium acetate
changes into a solid, it releases heat.
In fact, you know that the hot packs
that are used for first aid
have the very same sodium acetate in them
and all you have to do is initiate the crystallization.
I can report to you now that this also feels warm.
So this experiment
shows that the reaction releases energy
in the form of heat and we call that an exothermic reaction.
Did you like this experiment?
- Audience: Yeah. [applause]
- At this time, I ask you to join me in welcoming
my longtime colleague and friend, Dr. Rodney Schreiner.
Rodney?
[cheering]
Hello, Rodney. - Hello, Bassam.
- Happy to see you.
- I'm happy to here, especially on this 48th anniversary
of your special program.
- I'm very proud of that, 48 years.
- 48 years, that's amazing, isn't it?
[cheering]
- Yes, yes.
And we chemists like to commemorate anniversaries
featuring the element whose atomic number corresponds
to the anniversary.
- Bassam: Yes. - Do you know which element is--
- Bassam: Of course, I do. It's cadmium right there.
- Cadmium, right there, yes.
Number 48, symbol Cd for Cadmium.
Well, Bassam, I've brought you,
in honor of your 48th anniversary,
a sample of cadmium element.
- Bassam: Oh, it's heavy. - Rodney: It's very heavy, yes.
It is a heavy metal.
And like most heavy metals, it's toxic.
- Bassam: Oh, that's why it's inside the jar?
- That's why it's in a jar
so that we don't get it on our hands.
It is toxic.
And as you can see, it is a--
Like most elements, it's a silvery-gray metal,
but it has some unique properties all its own.
And I'd like to show you some of those.
- Bassam: All right.
- And I've got some equipment here to show you.
- It is heavy.
- Yes, it is.
Now, a cadmium like many metals
dissolves in hydrochloric acid.
And when it dissolves,
it produces a clear and colorless solution
of cadmium chloride.
The compound cadmium chloride.
So here is some of that solution.
And I have more of this cadmium chloride solution
in a beaker
and I'm going to add to that solution in the beaker
another clear and colorless liquid.
This is sodium sulfide solution. - Bassam: All right.
- Ok, so I'm going to pour some of the sodium sulfide
into the cadmium chloride.
- Bassam and Audience: Whoooo-oooo-ooo!
That's a beautiful color change, Rodney.
- Yes, yes.
So I started with clear and colorless liquids.
It's no longer clear, is it?
- Audience: No. - No?
Now it's cloudy because a solid formed in there.
And it's no longer colorless, is it?
- Audience: No. - What color is it?
- Audience: Yellow. - It's yellow, yes.
That solid is cadmium sulfide
from the cadmium chloride and sodium sulfide.
And that bright yellow color is used as a pigment.
If you go into an artist supply store,
you will find a bright yellow paint called cadmium yellow.
It contains cadmium sulfide, and there you can compare.
- Bassam: Is it safe to handle? Is it poisonous?
- No, this pigment and that paint is poisonous.
So artists need to be careful when they handle this paint.
And near the cadmium yellow paint,
you may find a paint called cadmium red.
Here's a tube of cadmium red.
Cadmium red doesn't contain cadmium sulfide.
It contains cadmium selenide.
- Selenide? - Selenide.
- Yes? - Yes.
It's a compound of selenium and cadmium.
- And it's red in color?
- It's red, yes, but it comes in different varieties.
This cadmium red paint,
you can get it in cadmium red deep, or cadmium red medium,
or cadmium red light.
And the light is sort of an orange-red,
and this is the deep red,
and the other one is, the medium is,
as you might expect, in between.
Now they are different colors because cadmium sulfide,
selenide color
depends on
the size of the particles.
So I've got here samples
of cadmium selenide
of different sizes.
Tiny, tiny particles suspended in a liquid.
And you can see they are different colors
and the size of the particles here
are about a billionth of a meter.
- A what?
- A billionth of a meter.
That's really, really tiny.
So tiny that you cannot see the individual particles,
but as we go across this range of colors,
the size of the particles just about doubles.
So you can see as the particles get bigger,
the colors get darker.
Now, not only does the color
depend on the size of the particles,
there's another property I want to show you.
And to show you that one,
I'm going to use this lamp
which you may recognize.
It is-- if I can get it to go on--
There, do you recognize that?
- Audience: Black light. - A black light, exactly.
And what I'm going to do is I'm going to set the black light
in front of these tubes.
And then I'm going to remove the white background.
And then we're going to turn off the lights.
- Audience: Whoo-hoo! Yeah!
- Rodney: Ohhhh, yes, something altogether different.
[applause]
Thank you.
Yes, they glow very nicely, and the color they glow,
also depends on the size of the particles.
The particles that are really tiny
give off short wavelength light
which is sort of greenish here,
and the bigger particles give off long wavelength light,
which is the red end.
So we see.
- Bassam: Do these particles have any practical use?
- Rodney: Yes, these are also sometimes called quantum dots
in the nanotech field.
And they're being studied for solar energy conversion
and for display panels like television sets
and you can see why.
They're very colorful.
- And the cadmium selenide is a semiconductor.
- Cadmium selenide is a semiconductor also.
- And that reacts to the changes in the UV light
depending on the size of the particle.
- Right, right, yes.
Now, while I've been working with cadmium metal
I've also been working with another metal,
one which is not toxic.
And I have a sample of it here.
This is iron in the form of a pipe.
[clink, clink, clink] Iron, metal.
- Bassam: It's safe to handle. - It's safe to handle.
This iron is not toxic at all.
But when I was experimenting with this
I discovered that I could pour sound.
- What?
- I can pour sound.
- You can pour sound? - Yeah, you want me to show you?
- Yes, would you like to see how he does that?
[applause]
- Ok.
I'll need your help, but I need--
There's a torch. - Yes.
- What we need to do is we need to get hot air
flowing through the tube in order to make the sound.
- All right.
- So if you start the torch, [torch flame hisses]
and then I'm going to hold the flame vertical, yes,
and I'm going to hold the pipe over it.
[windy echoing sound]
Now the hot air is flowing through
and it's making a sound that you can hear
but you're also listening to the torch.
So what we should do is turn off the torch.
[whistling]
There, now you can hear the sound.
And I can pour it into the cup. [whistling stops]
And I can pour it back. [whistling resumes]
[laughter]
And I can pour it into the cup. [whistling stops]
[cheers and applause]
And I can pour it back. [whistling]
- You're very good at this.
You're not spilling any of it.
[laughter] - I don't know.
Eventually. I must have spilled some.
- You spilled some? - It's gone.
- Oh, let's do it again. - Ok.
- Want to see it again?
- Want to see that again, ok.
- Audience: Yeah, yeah!
- Rodney: You get hot air going through the pipe.
You can kinda hear it whistling now,
but the torch is making so much noise.
We turn off the torch.
[whistling]
There. [whistling continues]
Pour it into the cup. [whistling stops]
Pour it back. [whistling]
Pour it into the cup. [whistling stops]
Pour it back. [whistling]
Let's see, could I do it again?
[whistling stops]
And...
Ahhhh...
Oh, well.
[cheers and applause]
How many of you believe that I'm actually pouring sound?
[laughter]
I don't see many hands.
Actually I'm not pouring sound,
I'm doing something completely different.
You want me to explain what I'm doing?
- Audience: Yeah. - Ok.
First, this tube is not completely empty,
there's something in the end of it.
And I'm going to see if I can show it to you.
At the end of the tube, let's see, aim it, there we go.
I think you can see there's a screen inside the tube
near the end.
So when I hold this, let's see,
when I hold it over the flame the screen gets hot,
then when I turn this vertically
that hot screen heats air, the hot air becomes less dense
and it rises through the tube
and it draws more through.
So it keeps going while the tube is vertical.
When I turn it horizontal
it can no longer rise through the tube
and so no longer makes noise.
When I return it to vertical it goes through,
rises and makes noise again.
So that's all that is involved.
This has nothing to do with it.
[laughter]
- Thank you so much, Rodney. Thank you, thank you.
[cheers and applause]
My next experiment uses this book.
I actually wrote this book.
It says Chemical Demonstrations .
There's my name down here.
You see at the bottom down there?
So with your permission, I'm going to open the book
and just remind myself of the instructions
for the next experiment, all right?
Is that ok if I did that?
- Child in Audience: No.
[audience oohs]
- This is not an ordinary book.
This is a hot book.
[laughter]
It's actually not a book at all.
It's the book cover.
And on the inside I have two batteries
that have stored in them chemical energy.
And then I have the filament from a light bulb up here,
and then there's a wick that I soaked with lighter fluid
when you were not looking.
[laughter]
And down here, you can see there's a small button.
Now when I push the button,
which I haven't done yet,
because the book is where?
[laughter]
Before I push the button,
I should move the book away from my face, right?
[laughter]
When the button is pushed, the chemical energy
that's stored in here changes into electrical energy
and the filament lights up.
This filament is like all filaments in light bulbs,
except LEDs.
It gives off light energy and also heat.
And remember from the fire triangle,
we need three things to have a fire.
You need something that burns,
oxygen, usually from the air,
and then you need... what?
A source of ignition.
So what should I do?
[multiple responses from audience]
Move the book away from my face.
[laughter]
And then push the button.
I don't have enough fluid there,
but I want to show you how this really works.
So I will get my lighter fluid.
And I want you to see how it's done, like so.
I close the book, put this on the side,
open the book.
What should I do next? - Audience: Push it away!
- Move it away from my face, yes.
I push the button.
And what's happening?
There it is.
- Audience: Whoa!
- So we teach about the fire triangle
not to help start fires
but to help put out fires.
Did you like this experiment?
- Audience: Yeah! [applause]
At this time, I would like you to welcome
a high school junior who is working in my lab.
Please welcome Isabelle Krier.
[cheers and applause] Hello, Isabelle.
[applause]
Very happy to see you. - Nice to see you.
- We're going to do some experiments.
You've been working on these experiments,
among other things.
And the experiment I'm going to do
is to take this colored liquid--
I you look near the top you can see
that it has a purple tinge.
It's so concentrated that it's dark.
I'm going to add to it a clear and colorless liquid
and we'll see what happens.
You ready? - Yeah.
- All right.
[oohs and ahs]
So what I did
is to bleach the color.
Color is something that we all really enjoy
and that's what you've been working on here.
So what do you have here, Isabelle?
- I have two beakers of nickel sulfate solution.
- Nickel sulfate. And what's the green color?
- The nickel in the solution is what makes it green.
- All right.
- So I can add some clear liquids here.
[audience oohs and ahs]
- Bassam: That's pretty.
- Isabelle: And now I'll add ethylenediamine.
[audience oohs and ahs]
- Bassam: All the blue is gone
and now I see violet, purple.
You have one more? - I have one more.
- Clear and colorless? - Yup.
- Let's see what's going to happen.
Oh, and if you don't mix it
you can see the two layers, right?
Now mix it to see what happens.
So beautiful color changes
always arouse our curiosity
and make us think about
the beautiful, complex world that we live in.
Now in my lab, we have many, many talented people.
Isabelle is one of them.
And I know that you are a musician.
- Mm-hmm. - What do you play?
- The violin.
- She plays the violin.
Would you like to hear Isabelle play the violin?
[applause]
- All right, so I play the violin.
And my violin's made out of wood.
And then I can make sound in my violin
with the four strings that all make different sounds.
I can also create sound with my bow,
which is also made out of wood,
but on this side it's horse hair
so that I can make sound by bowing against the strings.
[dramatic violin music]
*
[cheers and applause]
- Bravo, Isabelle.
She not only excels in doing colorful scientific experiments,
but she excels in making us all enjoy
the beautiful music that she's played.
Thank you very much, Isabelle.
Thank you so much, thank you.
[applause]
My next experiment is one where
I will take a source of gas--
propane gas
from this propane bottle.
And I'm going to use a burner
to light the-- [flame whooshes]
I use a sparker to light the burner.
Can you hear the roar of the flame? - Audience: Yeah.
- Bassam: What color is the flame? - Audience: Blue
- Bassam: Well, let's see.
I have some spray bottles right here.
And I'm going to use
this spray bottle in my left hand
and spray into the flame.
And I have another one in my right hand.
I'm going to spray this into the flame.
- Audience: Ooh!
- You know what we should do? - Audience: No.
- Do this in the dark.
Let's do this in the dark.
So with the lights down, here's the first one.
- Audience: Ooh!
- Here's the second one. - Audience: Ooh!
- Here's both together. - Audience: Ooh!
Alright, with the lights back up, please.
I have a third bottle here.
And this one has liquid in it, just like the other three.
But this one, this liquid, is a solution of sodium chloride,
table salt.
So, I'm going to spray this.
- Audience: Whoa!
This one had in it lithium chloride.
This one is sodium chloride.
This one is lithium chloride.
This one is boric acid.
We mix them together and we get
a beautiful mixture of red and green.
Happy holidays, everyone! [laughing]
[cheers and applause]
Well, you've been a wonderful audience
coming to join in the celebration
of the 48th anniversary of this program.
And that's why I want to salute you
by doing my grand finale.
- Audience: Ooh!
[applause]
Thank you all very much. Thank you.
Come on out.
[cheers and applause]
* [upbeat electronic music]