Genie in a Bottle
Preparation and Properties of Oxygen
Written by Steve Wojtas
1st Scientist pulls out the cork on the covered glass version
of “genie in a bottle” and condensed water vapor rushes out
the top.
1ST SCIENTIST
Pretty neat huh?
2ND SCIENTIST
This experiment always reminds me
of a genie coming out of a bottle.
1ST SCIENTIST
Or something that you see in a
magic show.
2ND SCIENTIST
Yeah. But one of the things I find
fun about science is that not only
do I get to see cool things like
this, I get figure out why they
happened and how they work.
1ST SCIENTIST
We're going to show you how we made
this "genie in a bottle effect"
happen.
1st picks up a 2-liter bottle.
2ND SCIENTIST
Now what do you see at the bottom
of this bottle?
Audience responds
1ST SCIENTIST
In science we want to be as specific
as possible. At the bottom we have
a clear, colorless liquid. What it
actually is, is a hydrogen peroxide
solution.
2ND SCIENTIST
That's the stuff that your Mom
might put on your cuts to clean
them. In fact, that interaction
with your skin is one of it's
properties that we're using to make this
experiment today.
1ST SCIENTIST
Right. Except the hydrogen peroxide
solution you use at home is only 3%
hydrogen peroxide and 97% water
while this solution is 30% hydrogen
peroxide and 70% water.
2ND SCIENTIST
Which is why we're wearing gloves
and goggles. Because if you think
the stuff at home stings, this
solution will really burn if it
touches you because the hydrogen
peroxide is ten times more
concentrated than the home
solution.
1ST SCIENTIST
Now as we're speaking, this hydrogen
peroxide is breaking down into
water and oxygen. But why can't we
see it?
2ND SCIENTIST
Because it's happening too slowly.
So we're going to use something
called a catalyst. A catalyst is
anything used to increase the rate
of a reaction that isn't used up in
the reaction.
1ST SCIENTIST
Our catalyst in this case is
manganese dioxide. I have it here
wrapped in tissue and tied to this
string to help me put in the
bottle. Now I'm going to add this
to the solution and I want you to
pay careful attention to what
happens.
1st drops the tissue containing the catalyst into the bottle
and the bottle expels condensed water vapor.
2ND SCIENTIST
What's coming out of the top?
Some might say steam
2ND SCIENTIST (CONT'D)
Well it's not steam, because you
can't see water in its gaseous
form. It's actually condensed water
vapor. It's water that was steam,
until it hit the cool air and
condensed into tiny water droplets
suspended in the air. That's the
part that you can see, the
condensed water vapor.
1ST SCIENTIST
What else happened? Look at the
bottle. Notice any difference?
Here, let me hold it up next to
another 2 liter soda bottle.
It shrank!
2ND SCIENTIST
That's right. It shrank. That's
because the heat from the reaction
softened the plastic bottle.
1ST SCIENTIST
And what's at the bottom here?
Audience responds.
1ST SCIENTIST (CONT'D)
And if you look at the bottom the
black powder is still in there,
mixed with the water created from
the breaking down of hydrogen
peroxide. If we measured the amount
of black powder it would be the
same as we started with before the
experiment because none of it was
used up in the reaction.
2ND SCIENTIST
What we've just been doing is
making observations. Careful
observations are very important in
science because they help tell us
what happened in an experiment and
whether we're on the right track.
1ST SCIENTIST
Let's repeat the experiment,
because in science we always like
to repeat our results, and this
time we'll look out for the things
we just observed.
The things we're going to look for
are condensed water vapor, a
shrinking bottle, and the catalyst
still remaining at the end of the
experiment.
1st puts the manganese dioxide in the last bottle.
2ND SCIENTIST
And what's coming out the top?
1ST SCIENTIST
That's right, condensed water
vapor. What happened to the bottle?
2ND SCIENTIST
That's right, it softened and
shrank. And where' the catalyst?
1ST SCIENTIST
Sitting right here at the bottom of
the bottle. You've all just help
make scientific observations. Well
done!