* [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]
[loud boom]
[surprised exclaims] - Whoa! - What was that?
- 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.
[chemical explodes]
[oohs and ahs] [applause]
[expressing anticipation]
- Let's have a louder countdown: three...
- Audience: Three, two, one.
[chemical explodes]
[oohs and ahs] [applause]
My next experiment is with methane gas.
And I'm going to light a burner
and...
there is a controlled combustion reaction.
I also have a tank of methane right here
which I'm going to open.
It's connected to this little pipe,
clay pipe that I have here.
I'm going to try to bubble this through a soap solution.
So here we go.
[bubbling]
There is methane going in there.
You can see the bubbles.
[cheering]
Let's try, just try--
Oops.
[cheering]
You know the methane is in there-- There it is.
[laughter]
Let's try to get a bubble up there.
There it is.
[laughter]
These are all controlled combustion reactions
which we do very, very safely.
And I'm going to turn off the gas valve here
and also turn this one off as well.
And at this time, I would like you to join me
in welcoming
University of Minnesota Professor Renee Frontiera.
[applause]
Renee is a chemist.
And earlier this year,
she was recognized
by the American Chemical Society
as one of the Top 12 Talented
individuals in the world
because of her determination
and her commitment to science
and to improving the role of science in the society.
So welcome.
- Thank you.
[applause]
Thank you.
I'm so excited to be back in your lab.
- Bassam: You've been in my lab before?
- I have, in fact.
When I was a kid, I grew up in Madison.
And my parents and I would come to your show
every single year.
We'd sit right about there.
- In fact, your parents are sitting right there.
- Renee: They are, in fact.
- Bassam: Please stand up.
Please stand up, Dr. and Mrs. Frontiera.
[cheering]
And welcome again. - Thank you.
So your show is a big reason why I ended up becoming a scientist
and I would love to do an experiment today.
- Please, please. - Ok.
So, here I have
a piece of solid carbon dioxide actually.
Here's a piece of solid carbon dioxide.
And you'll notice that I'm wearing these gloves.
- Yes. - These are to protect my hands
from the solid carbon dioxide just because it's very cold.
- Bassam: How cold is it?
- Renee: It is minus 78 degrees Celsius.
So that's a very, very cold piece of solid carbon dioxide.
- So I shouldn't touch it with my bare--
- You should not touch it with your hands, yeah.
Gloves are helpful.
- I have my own gloves right here. - Excellent.
So carbon dioxide is very interesting
because you can see
it goes directly from the solid state into a gas, ok?
It doesn't actually become a liquid ever,
and so it's going through this process right now.
And what we chemists call this
directly going from a solid to a gas is "sublimation," ok?
That's a chemical term.
Can you guys all say "sublimation?"
- Audience: Sublimation. - Excellent, yeah.
So carbon dioxide, also known as dry ice,
undergoes sublimation
and it goes directly to this gas that we can't see
and is mixing with the room.
And so I'm going to do an experiment now
with this solid carbon dioxide.
And you can see that I have these cylinders
full of some liquids.
These are all clear liquids,
but they're different colors, right?
You see the colors there?
What about these liquids here? - Audience: Blue. - Blue.
These ones? - Pink.
- Pink and...? - Purple. - Purple, ok.
So I'm going to take some solid carbon dioxide, some dry ice,
and just dunk it in there, and what do you guys see?
- Audience: Bubbles. - Bubbles, exactly.
So the carbon dioxide is bubbling.
And what's happening now? What do you see?
[multiple responses from audience]
Exactly.
It changed colors, right?
Are they all done? Did they change?
Yeah, ok.
So what we saw here is a chemical reaction actually.
So the carbon dioxide, it goes from the solid to a gas.
We see these bubbles.
It also reacts and it makes an acid in these cylinders.
And it makes a carbonic acid which causes this color change
because
we put some indicator molecules in here
to tell us what's going on.
So these cylinders have a molecule called Bromothymol Blue
and this is the measure of pH.
It tells us if the solution is acidic or basic
and we can see that it changed color, right?
What color do we end up with?
- Yellow. - Yellow.
So it's more acidic with this Bromothymol Blue molecule
that we added.
We also had another set
with a molecule called phenolphthalein.
What happened in this case?
We started with pink and what did we get?
- Audience: Clear.
- So they're both clear.
Clear means we can see through it.
But this one is colorless, right?
This one is pink and clear,
this one is clear and colorless.
And this tells us that this one got more acidic as well
with this phenolphthalein molecule.
Ok, and in this last set of beakers,
we've got something that we call a universal indicator.
So this tells us about the pH again.
We went from purple to... What would you guys call this?
- Audience: Orange.
- Orange, yeah, orangish or reddish.
Universal indicator has a bunch of different molecules in it
so we can read out the pH across the whole pH scale,
ok?
So let's try something else.
Can we add some solid CO2 to this cylinder on the left?
- Sure, I got my gloves on now
so I pick up the dry ice, couple chunks of dry ice
and put them in this cylinder right here.
I asked you to focus your attention on this one.
You know, you're free to focus your attention
on anything you want. [laughter]
We live in a free country.
But if you want to follow the experiment that
Renee and I are doing, focus your attention on this one.
As I drop chunks of dry ice into the cylinder,
count out loud how many different color changes you see.
- Audience: One... three.
And you also see
that in each of the cylinders
that Renee and I put solid dry ice
that there is--
what looks like smoke coming off the top here.
But it's not smoke.
It's actually a condensation
of the water vapor on the carbon dioxide gas
that's coming from the sublimation.
And right here, sublimation is happening.
But we can't see it because carbon dioxide gas
is mixing with air which is a mixture of gases.
But over here, it's mixing with liquid so we can see it.
- Yeah, so let's see what else we can do
with this condensed water vapor.
So I'm going to head over here and I've got this nice basin.
What's in this basin?
- Audience: Nothing.
- Nothing except for air.
You guys are smart, ok.
So what I'm going to do is I'm going to take
this big flask of hot water, this is just boiling water,
and I'm going to pour it in to my basin.
And what do you all see?
- Audience: Steam.
Actually, you can't see steam. It's invisible.
But we see this condensed water vapor, ok?
We see these little water droplets
that scatter the light, ok?
So now I've got my dry ice, my CO2,
and let's see what happens.
I'm going to dump it in.
[splashing] [cheering]
Hey, I'm still here.
I'm still here, ok.
Whoa!
[cheers and applause]
Yeah, look at that.
So this mist or condensed water vapor
is the fog that we made
when we reacted this dry ice with our boiling water.
And you can see, it's actually going down, right?
It's going, it's spreading all over the floor.
So if you guys have seen fog in movies,
this is sometimes what they do.
And it's going on the floor
because this mist is more dense than air.
And so it sinks down
and now it's spreading all over the place.
- And you can tell that Renee is still enjoying science
in my laboratory here.
Can't you tell that? - Audience: Yeah.
- Thank you so much, Renee, for coming.
- Thank you, thank you.
- Best wishes to you, thank you.
[applause]
I'd like to ask that you focus your attention now
right over here
where I have a cylinder that's filled with oxygen gas.
I also have a Thermos bottle,
what we call a Dewar flask.
It has in it a very cold liquid.
It's called liquid nitrogen.
I'm going to show you the liquid nitrogen
as I pour it into this other Dewar flask.
So you can see
the liquid nitrogen is boiling
as it fills the Dewar flask.
The temperature of liquid nitrogen
is minus 196 degrees Celsius.
It's really, really cold.
And it hits a warm surface and it boils off.
So we want to fill this up with the liquid nitrogen
and we will know that the glass has reached
the same temperature of minus 196
when the boiling stops.
But we're going to do a couple of other experiments
as that's happening over here.
This oxygen tank is connected to a copper coil
that I'm going to put into the flask,
the Thermos bottle,
that has in it liquid nitrogen.
I'm going to add more liquid nitrogen right there
and the other thing I'm going to do
is open the valve
so that liquid starts coming out
of this Tygon* tubing.
And now you see I can bend it a little bit,
bend it some, bend it some.
And now it's become stiff.
That's because we're able
to condense a liquid,
liquid oxygen and you can see it coming out of the opening.
So I have a test tube,
I'm going to collect the liquid oxygen in here.
Can you see what color the liquid oxygen is?
[audience responds tentatively]
Liquid oxygen is blue in color.
Now here's a question for you
as you think about this experiment:
The boiling point of liquid nitrogen
is minus 196 degrees Celsius.
Do you think the boiling point of liquid oxygen
is higher or lower
than minus 196?
And don't let the minus sign confuse you.
Is it going to be higher or lower?
You can see that the liquid oxygen is condensing
in the liquid nitrogen that boils at minus 196
so the boiling point of liquid oxygen is?
- Audience: Higher. - Bassam: Higher.
It's actually minus 183 degrees Celsius.
And now liquid oxygen is a very interesting liquid.
It has a much higher concentration
than oxygen that's in the air.
So I'm going to take this out, set it out here.
And I'm going to do an experiment
using liquid nitrogen,
but also using this horn gap magnet.
I take my pocket knife out.
I put it between the poles of the magnet.
Then you can see it's stuck in there.
I have to really pull it out.
There, I got it out.
So a very powerful magnet.
What I do is I take the liquid nitrogen.
I want everybody to see this clearly.
The liquid nitrogen,
I'm going to put this
in between the poles of the magnet
and you see that the liquid runs right through
as you would expect all liquids to do.
But if I take the liquid oxygen, let's see what happens
when I put the liquid oxygen in there.
[audience oohs and ahs]
The liquid is held between the poles of the magnet.
That tells us that this liquid is magnetic.
In fact, what we say is oxygen is paramagnetic
and it stays in there until it evaporates.
So let's do it again. Here we go.
There is the liquid oxygen.
Have you ever seen a liquid held between the poles of a magnet before?
- Audience: No.
[applause]
In this experiment, I want to call your attention
to what I have in the large beaker.
And it is very obvious
to anyone who looks at the cans
that one is floating and one is sinking.
And I ask you to think about the difference
between what's in the cans
that causes the diet drink to float
and the regular drink not to float.
I'm going to give you a hint.
You know the difference between a hint and a clue?
A hint is something that someone tells you or gives you.
A clue is something that you find on your own.
You know how you run around sometimes and you say,
"I have no clue"?
[laughter]
That's because you haven't found one yet.
Well, here's my hint.
This is 39 grams,
almost 40 grams
of sucrose, of sugar.
This is what is used
to add as a sweetener
to the diet drink.
So that's my hint and you can think about
this explanation that you come up with.
By the way, when you visit my website,
scifun dot org,
you will find, in the upper left corner,
you'll find an icon.
And you click on that
and it takes you to a place where there are instructions
for experiments you can do at home.
This is one of those experiments.
There are many other experiments
so please visit the website and enjoy the experiments,
as well as everything else that is on my website.
My next experiment
uses...
a baby bottle.
[audience chatters]
And...
a can of carbonated beverage.
This baby bottle has been slightly modified.
I have replaced the nipple that has the hole in it
where the milk flows out.
I've replaced that with
the rubber bulb from a medicine dropper.
And I'd like to show you how strong this piece of rubber is,
as I try to inflate it by blowing air
from my lungs.
Here we go!
[strained blowing, squeaking]
[laughter]
Can't do it, very strong piece of rubber.
So I now open the carbonated beverage.
You know why it's called carbonated?
It has carbon dioxide in it.
So, I'm going to open it.
I'm going to take the baby bottle
and fill
the bottle to the top with the liquid.
You see any bubbles? - Audience: Yes
- Those are carbon dioxide bubbles
coming out of the liquid
because they're no longer under a great deal of pressure.
Now I'm going to put the screw cap on.
I'm going to tighten this.
And what should I do next? - Audience: Shake it.
- You've done this experiment before?
[laughter]
Alright, I'm going to shake it.
- Audience: Whoa! [laughter]
And right there you see how strong
the pressure of carbon dioxide gas is
in the carbonated beverages.
It's able to inflate this strong piece of rubber
that neither I, nor any other human being,
can inflate with all the powers of our lungs.
But, you know...
you already know
what happens
when you put a carbonated beverage in your mouth.
When you drink it,
what do you do after you take a sip or two?
- Audience: Burp. - Yes, when you burp,
would you please do it gently and politely?
[laughter]
We burp because the carbon dioxide gas
is coming out of the liquid.
And do you know why we like carbonated beverages?
Well, some of them have sugar.
Some have artificial sweeteners.
Some even have alcohol in them.
We like them because
when we put the liquid in our mouth
the tiny gas bubbles come out of the liquid
and tingle us
and give us a pleasant sensation.
You also know that when the drink goes flat,
it's lost all its carbonation.
All the carbon dioxide has gone out.
So now I would like to release the pressure.
Let's see if I can do it slowly.
If I do it fast, you know I'm going to make a mess here.
Well, I made a slight mess here,
but that's alright.
And by the way, that's why I use this carbonated beverage
rather than one with sugar in it
because then my hands will get sticky.
I will not be able to do the experiment successfully.
Now speaking of carbon dioxide,
I have candles.
I'm going to put the candles right here,
and, of course, I'm going to light the candles.
It's the season, right,
to light candles?
So there's the first one.
There's the second one.
There's the third one.
Four, five, six.
And what I want to do is take a flask
and put some dry ice in the flask.
So I need to put my gloves on
because solid carbon dioxide, dry ice,
is at a temperature of minus 78 degrees Celsius.
So I'm going to put that, those chunks in there.
Oops, I missed.
That's all right.
And dry ice changes from being a solid
to a gas directly without melting
by a process we call sublimation
and that's what's happening right now.
But carbon dioxide has another interesting property.
Let's see if I can now take the carbon dioxide
and pour it down the steps here.
Here we go.
Ta-da!
[cheers and applause]
- Now I ask that you focus your attention
on what I have in this glass spiral assembly.
There's a funnel on top.
There's a glass spiral coming down
to an empty beaker.
It's empty except for? - Audience: Air. - Bassam: Air.
And I have two liquids:
a clear and colorless liquid
and a clear and? - Audience: Blue.
And what I'm going to do is mix those two liquids together.
And we'll see what happens.
But I want to mix them in the dark.
So, with the lights down, please.
Here we go. Lights out, lights out!
Lights out more, more, more! [laughter]
There we go.
[liquid flowing] - Audience: Ooooh!
- Isn't that pretty?
[audience murmurs]
- And the glow is still going on in the beaker at the bottom.
I can report to you
that the beaker is at room temperature.
So this reaction releases energy in the form of light.
And so please turn the lights on.
But not in the form of heat.
This is what we call "chemiluminescence."
Can you say chemiluminescence? - Audience: chemiluminescence
- You said that so well
I'm going to show you the same reaction in slow motion.
So, watch the monitor.
And, you see the glow coming down?
Collects down in the bottom beaker.
Chemiluminescence is related to something
I think all of you know about: bioluminescence.
You know about the firefly? - Audience: Yeah.
- That's a similar chemical transformation
taking place inside a living organism.
This one releases energy in the form of light,
but not in the form of heat.
Did you like this experiment?
[cheers and applause] - Yeah!
- 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]