* [upbeat electronic music]
- [cheers and applause]
[balloon pops] - audience: Oooh!
- Hello, everyone and welcome to my lab!
Are you ready to learn? - Yeah!
- Are you ready to have some fun?
- Yeah!
- Well, let's get started.
We always start by making sure
that we obey the safety rules.
You will notice I have my goggles on.
If you have not noticed, I'm pointing them out to you now.
And you also notice that I have a fire extinguisher right here,
ready to be used
just in case something goes out of control.
We're not planning on anything going out of control,
but we have it as a safety precaution.
It is part of the safety rules.
And if need be... [blasts fire extinguisher] we can use it.
I am going to set it here where you and I know where it is.
If it is needed, we will use it.
What I have in this bucket here is some carbon dioxide,
except it's not in the gaseous form.
It is in the solid form.
It's called dry ice.
So I put my gloves on
and I try now to get a chunk of dry ice.
And set it right here.
This is solid carbon dioxide.
It is at a temperature of -78° Celsius.
It's very, very cold.
And that's why I wear the gloves.
This solid is changing into a gas directly,
without melting
When a solid changes from being a solid to a gas
without melting, we call that sublimation.
Can you say "sublimation?"
- Sublimation.
- Sublimation is happening right now, but we can't see it.
How come we can't see it?
Because carbon dioxide gas is mixing with air,
which itself is a mixture of gases.
I want to ask you to focus your attention
on what you see between my two hands right here.
What shape are these objects?
- audience: Cylinders.
- Cylinders, and how many cylinders are there?
- audience: Six.
- And they have in them what looked like colored liquids.
We know they're liquids because from experience
we know what liquids do when we shake them up.
And they seem to be arranged in some kind of order.
This pair has what color liquid? - audience: Blue.
- This one? - audience: Pink.
- This one? - audience: Purple.
All right, so what I'm going to do now in this experiment,
I'm going to take chunks of dry ice,
and I'm going to drop them into these cylinders,
and we'll see what happens
as I drop the dry ice in every other cylinder--
not in every cylinder.
[audience chatters excitedly]
Does this help you see it better?
- audience: Ooooh...
- All right. Do you see bubbles?
- audience: Ooooh...
- Those are carbon dioxide bubbles
coming from the sublimation of dry ice.
We see them there because a gas is mixing with liquid.
Over here, we don't see them
because gas is mixing with air.
We also see beautiful color changes, right?
And we see something coming off the top here.
It looks like smoke, but it's not really smoke.
It is a mist.
It is the condensation of water vapor
on the cold carbon dioxide gas
that's coming from the sublimation process.
But some of the carbon dioxide gas dissolved in the liquid
and caused the color changes.
So, each of these pairs have in them dyes.
And these dyes change color,
depending on how acidic or basic a substance is.
To begin with,
all the cylinders had in them a basic substance
and different dyes, three different dyes.
And then, when carbon dioxide dissolves in water,
as we have in carbonated beverages, we get carbonic acid.
We drink carbonic acid. It is safe to do.
But, you see, the color changes
are because of the acid-base reaction that we have used.
In these dyes, when they change color,
they indicate to us that a reaction has taken place.
That's why they're called acid-base indicators.
They indicate a chemical change.
You like this experiment?
- audience: Yeah! [applause]
- Thank you.
My next experiment will be done using this burner
which is connected to the natural gas source.
Can you see the flame? - audience: Yeah!
- Huh? Not really, right?
I mean, I can see it, but it's not a good flame to watch.
Let me see if I can make it appear a little better.
So what I'm going to do is
take a liquid from this spray bottle
and I'm going to spray it into the flame.
- audience: Whoa!
- Now you can see it better.
How about if I take another liquid
from a different spray bottle and do this?
- audience: Whoa!
- This? And this?
How about together?
- audience: Whoa!
[applause]
- Well, what I have in this spray bottle
is a water solution of table salt-- sodium chloride.
When I spray that, this is the color that we see.
That's really cool also.
All right, and if I take a solution of copper chloride
and I spray that, I get this green.
Now, you tell me: is this green the same as this green?
Do they look the same? Huh?
Kind of, right? [indistinct chatter in audience]
What I really want to do now is spray this one
that has the lithium chloride in it
with this one that has boron in it, in the dark.
So if we take the lights down-- There we go.
One, two. There we go.
[cheers and applause]
- All right, with the lights back up please?
Thank you, thank you.
Did you like that experiment?
- audience: Yeah! [cheers and applause]
- All right, all right.
At this time, I would you like to welcome
my long-time collaborator and very special friend,
Dr. Rodney Schreiner. Rod?
- [applause]
- Hello, Bassam. - Hello, Rodney.
- I'm really happy to be here on this,
the 47th anniversary of your presentations.
- I'm very happy that you're here, Rodney.
Rodney has been coming to my presentations
and participating in them for 46 years.
- One short. - One short.
- [applause]
- Rodney: Well, you know, we're both chemists.
And chemists like to mark anniversaries with the element
whose atomic number corresponds to the anniversary.
This is the 47th anniversary of this show.
Do you know what the 47th element is?
- audience: Silver. - Silver, right, it is silver.
So I have brought you something--
- That doesn't look like silver, Rodney.
- [laughter]
- You're right.
It doesn't look like silver, does it?
What does it look like? - audience: Copper.
- It looks like copper
because it is copper.
Yes, but we are chemists so I think we can do something--
- All right. - Using the copper and silver.
So, we have a solution here.
- We do. We have lots of solutions.
Which one would you like?
- This one with the balloon on it.
- This one here? - Yes. - All right.
- This is a solution of silver nitrate.
There is silver dissolved in the solution.
And I'm going to put the copper
into that solution.
So dip it in.
And it immediately changes color.
It changes color because copper is a more active metal
than silver so it replaces the silver.
The silver goes onto the copper
And the copper goes into the solution.
It's very slow for that to happen
so we'll have to wait a while.
And while we're waiting, I want to show you
some more about silver.
I have another solution of silver.
This is exactly the same solution as that.
But I'm going to add to it some household chemicals,
and we'll see what happens.
The first one I'm going to add is this one.
What is it?
- audience: Baking soda. - Baking soda.
Do you know what the chemical name of that is?
Sodium bicarbonate.
Okay, so I have a tiny amount of sodium bicarbonate
dissolved in water.
In chemistry, we have to be careful about the amounts
because they make a big difference.
I going to add just a little bit
of sodium bicarbonate solution.
And watch carefully.
See if something happens.
[spin bar clinks quietly]
Did you see something happen?
- audience: No. - No?
You didn't watch carefully enough. - [audience laughs]
- Something actually did happen.
It became slightly, ever so slightly cloudy
because it now has silver carbonate floating around,
a little bit.
Let's see if we can make more appear.
This time, I'm going to add
a solution that comes from this.
Do you know what this is?
- audience: Drano .
- Brand name is Drano.
The active ingredient is lye, sodium hydroxide.
So now I'm going to add sodium hydroxide.
You won't have to watch quite so carefully,
I think.
- audience: Oooh!
- So we see some things now.
So it got cloudy, and it changed color.
What color is this?
- audience: Brown. - Rodney: Brown, yes.
Is brown your favorite color?
- No.
- I don't think anybody said yes .
- [laughter]
I'm going to see if we can change the color
by adding yet another household chemical--
That's this one.
- Salt. - Salt, okay.
So I have some salt dissolved here,
and I'm going to pour that
into the mixture
and we'll see what happens.
- audience: Oooh!
- It changed color.
It was brown and now it's...
- audience: White.
- White. Is white your favorite color?
- [multiple responses from audience]
I heard a few yesses , but still mostly no .
Let's see what we can do.
Now I'm going to add one more household chemical.
That's this one. What's this?
- audience: Ammonia. - Ammonia, okay.
So I'll add the ammonia, and we'll see what happens.
Well, you said you didn't like white,
so the white is gone.
- [laughter]
- And so is everything else.
Is this just like the solution I started with?
- audience: No.
- No, it looks like it, but we all know it's not
because I added a bunch of other things to it.
Now I want to add one more thing to that solution.
This is something you probably don't have at home
unless you're not very careful with your eggs.
What I'm going to add
is this solution.
Smells like rotten eggs,
because rotten eggs produce what's in this solution.
This is sodium sulfide.
and I'm going to add some sodium sulfide.
I think I'm going to stir it a little faster,
and then add some sodium sulfide.
Just a little bit at first.
You see the change?
It's turning sort of yellowish brown.
Does that remind you of anything?
Remind you of anything like
what happens to silver?
It tarnishes.
Yes, especially if you eat
your scrambled eggs with a silver fork,
your silver fork will get dark
because of the sulfide in the eggs.
Now I'm going to add
the rest of my sodium sulfide,
and...
it gets really dark.
Turns black.
Now I want to show you something else.
I have this tarnished spoon here,
and you can get rid of the tarnish
with ordinary chemicals that
you have at home,
and I'm going to show you how to do that.
Get my supplies.
First, you need a metal that is more active than silver.
Copper is more active than silver,
but you probably don't have a lot of copper around the home,
at least not any cheap copper you want to use this for,
but you do have cheap aluminum.
Aluminum foil is very cheap.
Aluminum is much more active metal than silver,
I've taken a glass dish
and lined it with aluminum foil.
And I'm going to put the silver spoon into that dish.
Now, nothing happens because
there are no solutions for the reaction to take place in.
So I need to make a solution.
The solution I'm going to make
uses baking soda.
And I'm going to put baking soda
in this beaker.
That was 60 cubic centimeters
of baking soda,
or a quarter of a cup, if you speak American.
[laughter]
And I'm going to add to it some hot water.
And because it is hot, I'm going to protect my hands
with some cotton gloves,
and get my hot water from down here.
See, it is genuinely hot.
It is boiling.
And I'm going to
dissolve the baking soda in the hot water.
Now the hot water is so hot that it causes
some of the baking soda to decompose.
You know what happens when baking soda decomposes.
It gives off a gas.
That gas is carbon dioxide.
So now I have a very hot solution
of sodium bicarbonate,
and I'm going to pour that hot solution
over the spoon and into the dish
with aluminum foil.
- audience: Oooh!
- And, the tarnish goes away.
- [applause]
- So I just want to show you that this spoon...
So you don't have to look at it only on the monitor,
there it is, all nicely clean and shiny again.
No more tarnish.
- Very nice, Rodney, very nice.
Is this an experiment that can be done at home?
- Yes, you certainly can do this at home.
In fact, the instructions are on the Science is Fun website
at scifun.org, S-C-I-F-U-N dot ORG,
scifun.org.
So you can get instructions on how to do this
with all the right amounts.
- Good luck to everyone in trying to
remove tarnish from your silver. - [applause]
- Thank you so much, Rodney. Thank you, thank you.
- [applause]
- I know that
you,
some of you, maybe all of you, like spaghetti.
Is there anybody who likes spaghetti?
- [cheers]
- All right, lots of people.
And maybe you are like me,
I stick the fork in there and
I try to turn it here.
I can see that some of the spaghetti
is coming up here, but that's not moving fast enough.
Let me see if I can make that move a little faster here.
So let me try this and see if this works here.
-[laughter]
- Okay, here we go.
[drill whirs]
- [laughter]
- Isn't this a better way of doing it?
- audience: Yeah.
- What I really want you to watch now
is this clear and colorless liquid
that I have right in front of me here.
It's a viscous liquid.
It doesn't flow very well.
And I have a crank up here.
What I'm going to do is
turn the crank
and see what happens to the liquid.
- audience: Oooh!
- The very same thing that the spaghetti did.
That's because this liquid has in it
long chains of material
that behave in a similar way
to what the spaghetti did.
Stop cranking. You like that?
- [applause]
- I'm may try to turn it the other way now
to see if the same thing happens.
You might have thought it'll go down, right?
But it doesn't.
So this is a polymeric substance
that behaves in the same fashion
as the spaghetti
when you try to do it with the fork.
You like this experiment?
- Yeah. [applause]
- For my next experiment, I'm going to use
a large glass beaker,
and mix in it different liquids.
Turn the light on.
Turn the motor on so you can see the bar spinning,
and I need two more liquids
that are right here.
So, what I do is
turn this like so,
and add the first liquid, a clear and colorless liquid.
I pour it in,
and it gets a little cloudy.
Then, I take the second liquid
and I pour that in.
And anything exciting happen so far?
- audience: No.
- Well the volume increased. That's not so exciting.
That's a common experience.
Ah, well, that looks like we have a tornado here, right,
at the top of the liquid.
I hope this is the only tornado you'll ever come close to.
I take the third liquid and I add that,
and there you see a change.
- audience: Oooh!
- So this is a beautiful experiment
where we mix three different liquids
and we see, there has been a change.
- audience: Oooh!
- What's going on?
- [audience murmuring]
- Are you seeing something that I'm not seeing?
- [laughter]
- The last time I looked at the liquid in the beaker,
the color was blue, deep blue, almost black.
Tell me when to look. Should I look right now?
I don't want to trip over anything.
Tell me when to look. Should I look right now: yes or no?
- audience: No. - Okay, I won't look right now.
- audience: Now! - Right now? You sure?
I don't want to trip.
Every time I look, it's deep blue, almost black.
Maybe you can help me better on this side. Okay?
Tell me when to look. - audience: Now!
- Right now, are you sure?
Don't want to trip over it.
Every time I look it's blue.
All right.
Help me out. Tell me when to look.
- audience: Now!
- Right now, are you sure, right-- absolutely right...
What's going on here?
What's going on?
Oh!
Whoa.
What is it that you were doing that I was not doing?
You were looking all the time?
I was looking all the time too.
But I wasn't looking here all the time.
Remember what I said before? Pay attention.
Pay attention to what's going on
so you don't miss out on the excitement
of beautiful chemical transformations that happen
when you mix chemicals together
and you do experiments safely.
This experiment is one of 50 known such reactions
called oscillating chemical reactions.
It was discovered by two high school teachers,
and it's named after them.
It's the Briggs-Rauscher reaction.
Briggs and Rauscher taught high school
chemistry and physics in northern California,
and about 40 years ago or so, they published a paper
in the Journal of Chemical Education,
describing this beautiful captivating behavior.
You like this experiment?
- audience: Yeah! [applause]
- I'd like you to take another look now at the
beaker that's turned blue in color,
the liquid has turned blue in color
where we have crystals of silver
on the copper that was cut
in the shape of a tree.
The blue color is because the copper is going into solution
as a result of the chemical reaction,
and the silver is depositing on the copper.
A very beautiful electrochemical reaction.
At this time, I would like you to welcome
our Lecture Demonstrator in the Chemistry Department
here at the University of Wisconsin-Madison,
Mr. James Maynard. Jim!
- [applause]
- Hello, Jim.
- Hi, how are you doing?
- Do you have something for us?
- Yes, yes I do.
So part of my experiment is probably here.
Let me see if I can find it. Oh, yeah, so we have this.
Maybe you've seen one of these before.
[torch flame hisses]
- All right. - Okay.
And then I have a small,
Erlenmeyer flask with a clear, colorless liquid in it.
- I see that.
- And I have this syringe.
- All right, that's small too.
- Yeah, I'm missing one more thing.
Let me get it.
- You are? All right.
- I hope it's not so small.
- Oh, not quite as small as the other parts, no.
- What is that, a long glass tube, right? - Yup.
- And what do you have at the bottom of the tube?
- There's a stopper on the top,
and there's a stopper on the bottom.
And inside here, there's a clear and colorless gas.
As you can see, it doesn't seem
to be doing very much right now.
- Right.
- So my experiment consists of taking this liquid,
introducing it to this gas,
mixing it, and igniting it.
And so I'm going to get started.
- All right. - Okay.
For this particular experiment--
I know you shouldn't do this at home,
so don't follow a bad example.
I've got to get up on the table. - [laughter]
- Okay.
So what I want to do is take
the syringe, and I'm going to
draw a small amount of this fluid out into the syringe.
Don't worry, it doesn't hurt a bit.
- [laughter]
- So I have a certain quantity of this,
and now I'm going to introduce this liquid
to the gas inside here.
And this is introducing.
- I can see the liquid flowing down, yeah, good, yeah.
- Yup, and I'm actually going to do a little more.
I don't like that. I need more.
More is better, right? - audience: Yeah.
- Yeah, I agree.
- Sometimes. - [laughter]
- Okay, so we continue the process.
Put just a little more in there.
Now I'm going to mix it.
And I'm going to start my torch, okay.
So, now I'm going to mix it in a rather special way.
One,
two,
and a half...
All right, now I think we're sufficiently mixed
to do this experiment.
I would like this in the dark please.
As dark as we can make it.
- What are you going to do?
- I'm going to ignite the gas and the mixture in this tube.
- Bassam: All right.
- I'm going to do so on the count of three.
One, two, three.
[tsch, vvvwhooommm]
- [cheers and applause]
- Bassam: I see lots of changes here.
- Jim: Oh, yes.
So this is sulfur that you see on the inside of this.
So the gas inside here
is called "laughing gas," nitrous oxide.
You may have heard of it.
This liquid in this small Erlenmeyer flask
is called carbon disulfide.
It has a structure a lot like carbon dioxide,
but as you can see it does completely different chemistry,
and so this sulfur is a product from the reaction that forms
nitrogen and water and carbon dioxide.
- Let's take a quick look, look at the monitor,
and see this very same experiment in slow motion.
You won't hear any sound.
There is the flame.
You see Jim trying to get out of the way there.
- All right. Thank you very much.
- Thank you, Jim.
[cheers and applause]
- You have been a wonderful audience.
I'm so grateful for the eruption of appreciation--
- [audience: Oooh!] - That you have given us.
I'm so happy that you enjoyed--
- [audience: Oooh!] - Doing experiments.
Thank you so much for--
- [audience: Oooh!] - Sharing the joy of science.
Thank you for coming.
Thank you, everybody. Thank you.
- [cheers and applause]
* [upbeat electronic music]
[cheers and applause]