Freezing liquid nitrogen

I've done that.

Quite a few years ago, in class, I had some liquid nitrogen thanks to the parent of one of my students, and I was able - with the help of a vacuum pump - to repeat this demonstration in class.

I'm not sure my students were nearly as amazed as I was, but it's a singular occurrence for me.

Very cool...(pun intended)...

How To Make Drawings Float With A Magic Water Marker

That's pretty cool, man.

It's no Animator v Animation or anything, but it's a neat way to show that polar and nonpolar substances typically don't mix.

Burning diamonds

As they say, "Diamonds are forever."

That's what they say, anyway, but chemically it's not remotely true.

Diamonds are just a covalent network of carbon atoms and occasional impurities. Those covalent bonds are fairly easily broken in a combustion reaction at a high enough temperature.

That's why I tried to convince my wife that cubic zirconia was the fare more durable, stable, long-lasting choice to show the permanence of our love.

She wanted a diamond, though.

Green hands and green horns

A couple of years back, one of my AP chemistry students asked me if I knew why her hand turned green when she played the French horn.

It wasn't something I was familiar with, but I had a decent guess that green on the hand was a reaction with something copper-based...and brass is certainly copper based.

With a little looking up and finding the various brass compositions used in brass instrumentation - 67-89% copper in the brass used, I feel pretty certain that it's the copper corroding and creating that green residue - on the instrument and on the hand.

My student - MK of the Eastman School nowadays - said that she tried one of the suggested solutions -  lacquer on the horn - and didn't care for how it changed the tone of the instrument. If anybody has a better suggestion, I'll pass it along to MK.

Carbide cannons and lamps, oh my

Simple enough, eh?

I remember my dad saying that he used to play around with toy carbide cannons when he was growing up. By the time I was a kid, however, carbide cannons as children's toys had gone well by the wayside because of the danger involved.

The Rose Hulman Fighting Engineers (seriously), however, still fired one off in their quonset hut of a gym (since replaced) back when I was a student at Wabash College and occasionally travelling to watch the basketball team. I can't remember exactly why they were firing off the cannon. Maybe it was for their football team and I'm misremembering things. I can't find proof on the internet either way.

Check out some more carbide toys after the jump - including a far safer way to demonstrate this reaction thanks to Steve Spangler and Bob Becker.

Is NON-BUOYANT WATER Deadly?

Yes...sort of...

The video above explains that aerated water in sewage treatment plants - the ones with warning signs saying 'non-buoyant water' - might not be as deadly and non-buoyant as advertised.

From a 1985 study in Indiana, a Mythbusters episode (see below), and a Facebook/LinkedIn post, it looks like aerated water isn't quite as deadly as the signs say.

People do drown in aeration tanks from time to time, and I'm sure it's a very unpleasant way to die, but it appears that the drop in buoyancy - while very real - is apparently counteracted by the upward flow of the bubbles in those tanks. There is also a current caused by the upwelling that can create a circulation pushing any object toward the pool's walls and then downward (sort of like the bubbles in a pint of Guinness).

So, should you ignore the non-buoyant water signs? Not at all.

But is the risk not quite as risky as it's been made out to be? Probably.

Enter the crystalverse

 

In our material science class at Princeton - and in most of the matsci classes that originated from the ASM summer camps, I would imagine - we grow copper (II) sulfate crystals from solution.

It's a fairly easy lab to do, and the students have a high success rate.

For most students, that crystal growing experience is an end, but for others it's just a beginning, a taste of a much richer world of crystal growth.

For those students, crystalverse would be a great resource as it provides instructions for the diy crystal farmer whether they want to grow crystals of copper acetate, monoammonium phosphate, sucrose, alum, sodium chloride, potassium ferrioxalate, or even pyramidal crystals of sodium chloride.

In every case, the procedure is largely the same - make a solution, let the solution cool and evaporate to form seed crystals, continue to let the solution evaporate to grow the seed crystals larger. The great things about the crystalverse website is that it has loads of tips and faqs to help you troubleshoot your growing.