Randy Sullivan presents Halloween and "Mole Day" demonstrations


Uploaded by UOregon on 27.11.2012

Transcript:
Good day, natives of the New World! My name is Aristotle. I came back across the River Styx to set you straight
on what has been passing for natural philosophy at this institution.
I'm Randy Sullivan, I'm a senior
instructor here in the chemistry department at the University of Oregon.
Every year we have a
combination
"Mole Day,"
Halloween pumpkin drop.
And we
generally tag a few demonstrations along with it.
It's sponsored by the Student Affiliates of the American Chemical Society,
a student chemistry group here. It's to celebrate "Mole Day"
which is officially on
10/23, because
a "mole" is 6.023 times 10 to the 23rd, as we all know.
It occurred to me that the demonstrations that I had scheduled

to warm up the crowd for this pumpkin drop
were all very easily
explained in terms of the classic Greek four element theory:
Fire, earth, air and water. It occurred to me
that I would
present myself as being possessed by and channeling Aristotle
who presented these in some of his writings. Inside this balloon, we have a substance named "hydrogen," which is its true name in this country.
They would have you think this is an element -- ha ha!
Everyone knows that this substance "hydrogen" is simply a mixture of fire and air. I can prove it -- we'll
get the fire back out of it
with a little bit of a bump! We'll release the fire from the substance. (balloon explodes) There! There goes the air! Back to its proper sphere.
It is a reaction of iron oxide
powdered very finely with aluminum powdered very finely.
Get it to a high enough temperature, which I do by burning magnesium,
releases a tremendous amount of heat,
enough to both melt the iron and the aluminum oxide.
I run it in a flower pot,
and it drops out the bottom of it, you see molten iron and molten aluminum oxide.
I take a 55-gallon drum
and heat it up.
First I open the top of it,
pour in
a gallon or two of water,
and put it on top of a burner and heat it until the water boils for some time,
making sure that
while I'm heating it,
the cap is off of it so that pressure does not build up in it.
When I have a good head of steam in there, when it's gone for awhile,
basically all the air's been displaced by steam, by water vapor.
And then I shut off the burner, first,
then I cap it,
and then I toss it into the fountain.

It condenses the water vapor because steam does not like to remain as steam
at room temperature, the very cool temperature of that fountain, condenses
and creates a partial vacuum, and so atmospheric pressure crushes the drum.
We freeze pumpkins
in liquid nitrogen
which is
negative 195 degrees celsius or thereabouts, so it's very cold,
and
being good scientists, the first thing we do is drop a non-frozen pumpkin, a room
temperature pumpkin, off the roof of Onyx Bridge,
about four stories. (drops pumpkin) CHEERS
And then we follow it up with,
this year, several
frozen pumpkins. Man on roof: Here go the frozen ones! (drops pumpkin) CHEERS
You guys want to see more? Here goes a big boy! (drops pumpkin) CHEERS
Videographer: Is there a scientific principle at work there?
It's what we used to call in college a "gravity check" --
to make sure that gravity is still functioning.