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.

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