Science
Fun 2009
We
were invited to do a science show for the High School at the Performing
Arts Center and then
repeat it for the general public in the evening.
It is a lot of fun for
us when we get
to demonstrate how science can be
used to generate some cool effects.
I asked for some
volunteers to help
out and had a good supply of eager
helpers.
We started out by having
the first
two hold up a string with some blank pieces of paper hanging on it.
(She must have been a
friend of the
photographer because we only got her
picture.)
When we sprayed some secret chemicals on
them the
message "SCIENCE FUN" was revealed
OK, it isn't a big
secret so you
might find the chemicals listed elsewhere on this page.
We had some more
students help us
determine how much weight two eggs
will support.
We used a lever with the
fulcrum (a
hinge) holding up one end and the
eggs supporting the other.
Our volunteers would
weigh in and
then step up on the lever near the
fulcrum.
They would then slowly
move toward
the end supported by the eggs.
The lever was marked to
show what
fraction of their weight the eggs
were holding.
A second and then a
third student
followed the first.
We kept track of the
total on a
spreadsheet that was projected behind
them.
Here they are about to
perform the
test.
The first student got
clear to the
end with all their weight on the eggs.
The second got to where
about 92% of
his weight was on the eggs.
The third got to more
than 80% and
the fourth student was more than half way out when the eggs gave way,
The pair of eggs
supported nearly 400
pounds.
We had a little
discussion of
what a total solar eclipse is like and why they occur.
We wanted to make sure
they knew it
would be worth their time somewhere on this dark band on August 21,
2017.
On that day a total
eclipse will
sweep across the US.
We have managed to see
three of them
and they are spectacular.
Back to chemistry.
This time showing that
the color of a
flame depends on the elements
that are included in the fuel.
The camera didn't
capture the true
colors that you see in person but there is no question that they are
different.
We used silver nitrate
and magnesium
powder to show that a tiny drop of water can set off a violent chemical
reaction.
No picture of
that demo though..
It was too bright for
the camera.
A slower demo is the
destruction of
sugar by concentrated sulfuric acid.
The chemical formula
for
sucrose (that's sugar's chemical name) is C12H22O11
and that of sulfuric acid is H2SO4.
Take a half a
cup of regular
table sugar add enough concentrated sulfuric acid to thoroughly wet it
and wait.
The sugar turns brown
but not much
else happens at first.
The acid is a powerful
dehydrating
agent, ripping the water from the sugar.
Look at the formula for
sucrose again
and notice that there are exactly twice as many hydrogen atoms as there
are oxygen.
Water, H2O,
also has twice as many hydrogen atoms as it does oxygen so as the acid
removes all the water what is left is carbon.
The reaction also
produces a lot of
heat so much of the water is in the form of steam.
As the reaction starts
to produce
heat the rate increases so heat is produced faster.
The result is a column
of carbon foam
rising from the cup with bubbles made by the steam making it quite
porous.
Now for some liquid
nitrogen
experiments.
It looks like water but
is very cold,
-196° Celsius (-320° Fahrenheit)
That is just 77 degrees
warmer than
the coldest anything in the universe can be.
With Nancy keeping me on
track with
props for each part of the demo we showed balloons shrinking and
expanding.
We made liquid oxygen
and
demonstrated some of it's properties.
And froze and broke
flowers
Here the power to the
light goes
through a long wire .
The resistance reduces
the light from
the bulb.
But when the wire is
cooled it's
resistance goes down and the bulb gets a lot brighter.
Not "superconducting" but it probably should be called "real good
conducting".
Finally two teachers
helped us make
ice cream.
It took about 20 seconds
from the
time the liquid nitrogen was added.
For more information
about liquid
nitrogen go our cryogenics page.
BTW the secret message
was written in
two ways.
The first was with a
baking soda
solution (a mild base) which was then allowed to dry.
It was revealed with
grape juice
concentrate which changes color depending if it is acid or basic.
It was messy but it
works.
We also used goldenrod
paper with
letters written with a clear paraffin block used as a crayon.
Goldenrod paper is
another acid base
indicator.
When a window cleaner
(another mild
base) was sprayed on the paper it wetted it and turned the uncoated
parts bright red.
We will be doing another Science Fun program next school
year.
Send us email and we will let you know when it is scheduled.
Go to our Science Fun
page
Go to our Travels page
Go to our Personal home
page
Go to our Community page
E-mail Nancy and Alan