Science Week

[Sam]

Science Week is coming up.

I would love to do some very cool demos during the lunch breaks.

I have some ideas;

Diet Coke and Mentos
Dry Ice Experiments
Bang Test (similar to the pop test but a bit bigger)
Vinegar and Bi Carb Volcanos

But i was hoping that you all would have some more ideas.

PS: I love the new smilies

Thanks

[smiley]

Hi Sam,

We downloaded details on how to make an air pressure rocket launcher from the NASA website- always good for some Ooohs and AAAhs. Its pretty cheap to make - cheaper than buying a ready-made unit.

You can do comparative demos of Mentos & Diet Coke v Test tube full of salt & Diet Coke.

Also, the "Elephants Toothpaste" experiment is always a winner. We usually do it as a demo after the kids have done some catalyst experiments. It's real bucket chemistry:

Take one large measuring cylinder 250 or 500mL (I actually use a plastic one).
Add approx 8cm of 30% H2O2 (yes I said 8cm, meaning a proportion of the height of the cylinder, not a liquid measure).
Chuck in a good squeeze of detergent concentrate.
Rave on a bit about how elephant's have these really big tusks, and scientists had to develop a way of generating enough toothpaste for an elephant to be able to clean them all.
Add a catalyst. Manganese Dioxide works, but the resulting bubbles are streaked black from all the powder. Potassium Iodide works best, but don't let the little dears touch the bubbles.

Cheers, K

[Sam]

Thanks, (nice to know that i am not the only one who thinks for the students as the "little dears" )

I will of course have to try out each of these several time before hand just to see if they work.

We do the air pressure rocket with one of our units, so most of them have already seen and done that one. But the elephant toothpaste looks intresting. Thanks

[smiley]

Yes, actually its "Little cherubs" most of the time in this faculty.

Another fun one is microwaving marshmallows and putting marshmallows in a vacuum. You get the same result from two different procedures. If you microwave them on paper plates the cherubs can eat the results.

And for real fun you try exploding watermelons! Just google it and you should find a list of science videos from Steve Spangler in the US. Total insanity, and easier than pumpkins.

We have established "Exploding Wednesday" as an end of semester tradition for the Senior Chem students - after all, they're always asking if they can blow things up. So we do H2 balloons on a string and a candle on a broomstick to detonate them, exploding watermelons, glycerin & KMnO4 etc, and dry ice in a coke bottle - the hugest laugh ever!

Cheers, K

[Sam]

what would you put into the watermellon to make it explode like Steve got them to???

How do you get the balloons that full of H2? Any of the things i know how to do ends up with not enough of a reaction to fill the balloon?

What happens with the Glycerin and KMnO4?

[Ian]

Are we still allowed to do the Permangernate and glycerol one? Itused to be a regular, especially for volcano dems, but the teachers here won't do it any more.

We had fun last term when our Physics teacher ordered in some Liquid N2. There was about 9L left over, so I was invited in to one of the year 7 classes as "The Mad Professor" and did a series of dems for them, freezing flowers and rubber tubing (and shattering it with a hammer - behind a safety screen, of course!), freezing "super balls", inflating deflated balloons and deflating inflated balloons, popping yougurt containers,etc. It was a buzz! The kids enjoyed it too!
ian

[smiley]

Answering questions in order:

1. I'm guessing a little container of Zn bits. He adds HCl and then ignites it using one of those long BBQ/Candle lighters. If you look at the video carefuly you can see a hole in one of the watermelons where he inserts the lighter, and I'm betting he generated H2.

2. H2 balloons are made in a 500ml flask with lots of torn up Alfoil and 2-3M NaOH poured over the it. Prestretch a balloon by blowing it up and deflating a few times(do this first), then stretch over the neck of the flask as soon as you've poured the NaOH in. (NB Not too much NaOH and it will bubble up the neck of the flask) Once the balloon is big enough, wrangle it off the neck of the flask, and quickly tie it in a knot, which you have to pull very tight. All this is best done in a lab sink, with washing up gloves on (as well as all the other safety gear ), as it is hot and you are messing with hot sodium hydroxide. Practice is a good idea too.Cut any excess rubber off from the end of the balloon and attach a cotton reel to the balloon. Let it float to the ceiling, or about 1.5m above you if you're outside. Sticky tape a candle to a metre ruler, light it and hold it up to the balloon. then DUCK! Don't delay too long as the H2 can leak out of the balloon pretty quickly.

3. Place a little pile of KMnO4 on a tin lin (eg a Milo lid) in a fume cupboard or a clear area outside. Add a few drops of glycerol. What happens at first is a great deal of nothing. So then you say "Oh dear, I guess it's not working today etc etc" and all the kids go HA HA. Then suddenly it will start crackling a bit, so you cup one hand to an ear, dramatically. Then the whole lot will go up in PINK flames! Yahoo.

I won't answer the "are we allowed to do that?" question on the grounds that it might incriminate me! My defence will be we're in the country here (imagine a slow drawl) so we might be a bit behind the times ya know?? Anyway, we only do it as a demo. It's an old bushies trick - how to light a fire in the wet.

Cheers, K

[Sam]

I am up in Darwin so i think that i will be able to get away with it as well.

Thanks for your help, I had a look on the web and i found an explosive watermelon and pumpkin prac as well.

I will check in and tell you how all of it went.

Sam

[smeee]

Steve Spangler science has demos and instructions on some interesting pracs

[Sam]

The problem with Steve Spangler is that he does not write in the chemical and preportions that he uses. Probley a liability thing, but it makes his site very interesting but not very practical.

[J]

The Surfing Scientist on the ABC website is worth a try. All sorts of odd things and conundrums that will confound and baffle your students. Some are ordinary and predictable
some are good fun and will have them mystified.

This guy did a presentation at the last St Marys conference. His tricks are simple and most use ordinary household stuff.

Have fun
Julie