[festive instrumental music]
[UW-Madison Marching Band playing "On, Wisconsin!"]
[pressurized spray]
[cheers and applause]
- Hello, everyone,
and welcome to my lab.
I'm especially pleased that you are here
to celebrate this very wonderful anniversary.
And I want to thank the UW Band for being here.
Weren't they great?
[cheers and applause]
They'll be back, they'll be back.
So, thank you very much.
I appreciate you being here, and we'll see you shortly.
[cheers and applause]
So I ask you to pay attention
because if you pay attention you're going to learn.
And I want to make sure that you are really paying attention.
What does my T-shirt say?
- Audience: Science is fun.
- Oh, come on, you can do better than that.
What does my T-shirt say? - Audience: Science is fun!
- That's it, we need to have some enthusiasm
as we do experiments!
I'm going to use these four beakers
that have in them the same green-colored liquid
and I'm going to add
different clear and colorless liquids to them
and we'll see what happens.
So I'll use this on my right,
on your left, as a reference.
I open this container and I add some...
household ammonia.
You like that, huh? [audience laughing]
I'm glad you like that.
I like that, too.
Color changes tell us that something is happening
and in science, we try to understand
what it is that's happening
so I take a different clear and colorless liquid now,
I add that and...
you get another transformation.
Here's a third clear and colorless liquid.
What would you predict is going to happen now?
- Audience: A color change. - Any color change?
- No.
- How do we find out?
- Audience: Experiment.
- Just stop talking and do the experiment, right?
[audience laughing]
Here we go.
[audience oohs and ahs]
And we can mix those...
and we can mix this one, too.
You notice this one has a solid at the bottom.
Let's try to mix it to see if the solid disappears,
and we get these beautiful color transformations
by adding different liquids
that combine with the heavy metal that's in there.
The green color is because
we have something called nickel sulfate.
These are compounds of nickel that combine differently
with the different reagents that we have.
So, here's another one that I want to do.
I have a beaker.
It's empty except for air.
It's the same size as the other beakers.
You're paying attention, right?
'Cause if you pay attention, this is how you learn,
and this is how we process information
and this is how we start sharing information
as we learn from what we have observed
and made connections
with the experiences that we've had.
So, this beaker is empty except for air.
I'm going to take a clear and colorless liquid
and put it in it like so.
And then, I'm going to put the cap on.
Why do I put the cap on?
Just in case I knock it down, right?
We practice safety all the time.
And then I take a clear and colorless liquid
and add just a little bit of it and there we go.
- Audience: Whoo!
- Oh, you like this one? - Yeah.
[cheers and applause]
Now I want to walk over and do an experiment right here.
Where you see I have
a large flask.
It's empty.
Actually, it's not empty.
It has in it a clear and colorless gas,
and it is connected
to this large beaker
that was water in it.
And there is
a stopcock here which I'm going to turn.
And then, I'm going to also
squeeze this small rubber bulb
that has in it just a tiny bit of water.
So first, I open this
and then I squeeze.
And a small amount of water is dissolving
the gas that's up there.
The gas is called ammonia.
Ammonia is very soluble in water.
And then, the pressure in the upper flask
gets to be lower than it is,
and you see the atmospheric pressure
is pushing, is siphoning the liquid up here.
[liquid pouring]
[cheers and applause]
The next experiment I'm going to do
has to do with water.
And I have
several beakers.
Five of them are the same size
and this one is bigger.
And then, I have two of the beakers
that have water in them.
And what I'm going to do is use some household chemicals
to study some of the properties of water.
The device I'm going to use is this light bulb
that is not lit right now
because the circuit is not completed.
It's plugged in,
but let me show you what happens
when there is conductivity.
You get a bright light.
So, if I take this apparatus
and I put it in water,
I don't see any light coming on at all.
That's because water is a poor conductor of electricity.
If I go to a different liquid,
which I'm going to add right now.
This is household chemical ammonia--
I'm sorry, this is vinegar.
And then...
this one is the ammonia.
Let's see if we can learn something
about the conductivity of vinegar.
You can't see the light.
Can we turn the lights down please just a little bit?
So, vinegar is not as poor a conductor of electricity
as water is, but it is very poor.
So I take this out,
and the lights back up again, please.
And I rinse in here in between experiments
because I do not want to contaminate
the vinegar with the household ammonia.
We try the ammonia.
Let's see.
Can we have the lights down, please?
It is also a weak conductor of the electric current.
That means that ammonia, household ammonia and vinegar
do not have many ions in them.
So, I rinse one more time.
And then, I'm going to go back to the ammonia,
but I want to add-- The lights up, please.
Now I want to add the vinegar solution,
with the lights up, please.
Thank you.
And as I add this, you see me do it.
[audience gasping]
'Whoa' is right.
When you mix the ammonia with acetic acid
you get ammonium acetate
which is a very strongly ionic substance.
And so, we learned from this experiment
that the electric conductivity
is a way
by which we can tell how many ions we have in solution
using this very simple device.
And by the way, this is an experiment
that you can do at home.
If you have a device like this.
[audience laughing]
And if you go to my website scifun dot org,
you will find the instructions for making a device
similar to this so you can do this experiment
and many other experiments that have to do with conductivity.
[applause]
Please welcome to my lab
the Pro Arte Quartet.
[audience cheers and applauds]
[Haydn's String Quartet in B-flat "Opus 76, No. 5, mvt 1"]
*
[audience cheers and applauds]
Thank you,colleagues from the School of Music.
Thank you!
Ladies and gentlemen, one more round of applause
for the Pro Arte Quartet!
[audience cheers and applauds]
- At this time, I would like you to welcome
someone who's been working in my lab.
Please welcome Julia.
[audience applauds]
Hi, Julia! - Hi, Bassam.
- Happy to see you! - Good to see you, too.
How are you? - I'm fine.
What have you been working on?
- Well, I've been doing some experiments with air movement.
Air is a fluid and it moves,
but everybody knows that, right?
- Yes, yes.
- So, I have here a balloon,
and I'm going to blow air, that is, move air into it,
and it will inflate.
[blowing sound]
So, you saw that I had to blow harder
when I inflated the balloon initially,
and then, once I stretched the rubber out
it was easier, but you've inflated balloons before, right?
- Shakhashiri: Yes.
- You guys remember that, right?
Oh, no!
This one has a hole in it.
- It has a hole in it? Oh.
- We better get another one. I need this.
- Well, we have more balloons. - Okay, we have more balloons.
- Yeah. [blowing sound]
A little too big, I think.
- That's good.
So, air movement: you blew air into the balloon,
you inflated the balloon. - Yes.
- You worked harder at the beginning.
Everyone knows that.
- All right. - You tie the balloon.
This one doesn't have a hole in it.
Good. - Good.
- Now, I also have here a hair dryer.
- Yes.
- And when I turn the hair dryer on,
a fast stream of moving air
is going to come out of the nozzle.
[hair dryer whirring]
Now, if I take the balloon and do this.
- Whoa, that's cool. - Yeah, it's suspended
in the moving air coming out of the hair dryer.
- So the stream of air that's moving from the nozzle
is holding the balloon up there?
- Right, so if I block the air...
- It falls down. - The balloon comes down.
It's pretty cool, huh? - Yeah, it is cool.
[applause] - Now, watch this.
- Whoa.
Bravo, Julia.
- Thank you. [applause]
- That was really cool.
- Thank you.
Now, air movement is what I want to tell you more about.
So, I have another experiment that I want to do
and I want you to help me with it.
- You want me to help you?
- I do, so. - I'm ready.
- Here, let's take this
and let's move around to the front of the table.
- All right. - So everyone can see.
So, I have a long piece of plastic here
and I'm going to give you one end.
- Yes, I can see that.
- I'm going to hold the other end.
There's an opening at my end.
Is there an opening at yours? - No, mine is sealed.
- Okay, here, you take this end
and I want you
to inflate this long tube by blowing into it.
- This whole long tube? - Yes.
- Just blow air into it?
- Yes, and we're going to count how many breaths it takes
for him to inflate it, okay?
- Okay. - All right.
One, two,
three, four.
Okay, okay, you can stop.
I don't want you to hyperventilate.
- Yes, thank you. [Julia laughing]
- Let's see how well you did.
All right, not too bad, not too bad.
- I tried. - Yes.
Okay, now I want to show you and everyone else
how I can inflate this with a single breath.
- Shakhashiri: No way.
- Watch, here you take this end.
- This is the sealed end. - That's the sealed end.
I'm going to take the open end.
Now watch this.
- Whoa.
[audience cheering and applauding]
- I like that. - So, what happened is
when I blew a stream of air down the middle of the tube
it created a partial vacuum around that stream of air
and that sucked in more air from around it.
- Huh. - Would you like to try it?
- Sure, I'd like to try it.
- All right, let's--
- Where are you from, Julia?
- I am from North Carolina.
I was actually home-schooled in North Carolina.
- Oh really? - Yeah.
I went to college when I was 11 years old.
[Julia laughs]
And I graduated from
the University of North Carolina- Wilmington
when I was 16,
with bachelor's degrees in chemistry and biology.
And then I came here to the University of Wisconsin- Madison
to enroll in a biophysics graduate program
and I got my Ph.D. in 2017 when I was 23 years old.
- Whoa! [applause]
- But I want you to try the experiment.
- Well, yes, Dr. Nepper,
I will do whatever you want me to do here.
So, let's see. I hold this up like this, right?
- That's right.
- And then what do I do?
- Just blow a stream of air down the middle.
Okay, now close it off quick.
Wow!
[applause]
Great job, Bassam. - Thank you so much.
- I love working in your lab.
- Thanks. - It's so much fun.
- I love having you in my lab, too.
Thank you so much.
Please give a big round of applause to Dr. Julia Nepper.
[applause]
My next experiment is going to be done
using a very cold liquid.
This liquid is called liquid nitrogen.
Liquid nitrogen
is kept in a container like this
so it remains cold.
And I have two other small containers
that I'm going to retrieve and use
to show you
some of the properties of liquid nitrogen.
So, I take the liquid.
Ah, it's heavy.
I put it in this thermos bottle that's clear.
And you can see the liquid boiling.
That's because the glass is at a higher temperature
than the boiling point of liquid nitrogen.
Liquid nitrogen boils at minus 196 degrees Celsius.
Really, really cold.
And it continues to boil until the temperature of the glass
gets to be the same as the temperature of the liquid.
So, we're losing a lot of heat here to liquid nitrogen.
We fill it up
and one of the interesting properties of this liquid
is that you can pour it on,
you know, use it for dusting you know, just like that. [laughter]
It's a very expensive way to dust things.
So there are lots of interesting things that we can do.
Here is a balloon tethered as you see it.
I'm going to pull it down
and I'm going to pour some liquid nitrogen.
Oh, some of you are covering your ears again.
So I add this.
[tsssscccchhhh]
And what's happening?
The balloon is collapsing because the helium atoms
that are inside are slowing down
because of the cold temperature on the outside.
I pour the liquid out. It's all gone.
And now, as the liquid evaporates,
what happens to the balloon?
[crinkling and crackling]
[cheers and applause]
It goes up again.
[applause]
I need a little more liquid nitrogen here.
You can see when the cold nitrogen gas comes out
we get that condensation again of the water vapor.
And what I'm going to do next
is take one of these chrysanthemums,
it's a nice piece of flower here, right?
And put it in the cold liquid nitrogen.
[tsssscccchhhh]
And I'm going to pull it out.
It's not as pretty as it was before
and it's much more fragile [crinkling and crackling] than it was before.
- Audience: Oooh!
[applause]
You have been a great audience and I want to thank you
for coming here to share in the joy of science,
the joy of the arts,
and to be enjoying whatever else you do
when you do experiments.
Thank you very much for coming to this special celebration.
I want to invite all my coworkers to come out.
C'mon!
[UW-Madison Marching Band plays "On, Wisconsin!"]
[clapping along with the song]
[cheers and applause]