As I noted in my above post, you can’t have bending modes with a diatomic molecule. Ditto for twisting (“torsional”) modes.
I sometimes visualize a molecule as a set of those Tinker-Toy-like models, a Framework Molecular Model kit or something, with the wooden or p0lastic balls connected by wooden or plastic sticks, or (better) springs). In that case, I can easily imagine “bending” a diatomic molecule made of two balls and a spring, or twisting it.
But my improved mental picture of a real molecule isn’t like that. The orbital shells are big enough to touch and overlap. The orbital shells aren’t solid, but made up of electron probability clouds (you can think of them as rapidly moving electrons).
When you bend or twist your molecule model, you do it by exerting force on the outside of your spheres with your fingertips. Try doing that with your Electron MicroForce probe on a real molecule and it won’t happen. For practical purposes, all you can do with a real molecule are things that involve pushing, not any kind of twisting. So you can induce bending motions in a tri-atomic molecule like water by pushing the two hydrogens toward each other. If you try to bend N2 or CN all you do is push the atoms together and maybe rotate the molecule.
Well first off, not all microwaves have glass plates in the bottom.
Secondly, in every “safe” set of instructions I’ve seen for microwaving CDs, there’s a reccomendation that you put a microwave-safe mug filled with water in the back corner of the microwave to provide the minimum load.
However, I’ll agree with everyone else: I’ve never seen an empty microwave give a lightshow.
And since everyone here is talking about fun with microwaves, here’s a link to an interesting .pdf from a US Department of Energy “Lessons Learned” site. Scroll down to Event #2, “Near Miss From Explosion in Microwave Oven”. Two seperate stories of microwave oven related incidents at Department of Energy facilities.
ok, neither Nitrogen nor, I presume, any of the nobel gases would do much of anything when stuck in a microwave.
But say we WANT to find something that does, along the same lines as suggested in the initial question.
What about liquid CO2? It’s not a bent molecule like H2O, but there’s a little more to it the simple Nitrogen, right? Would it do anything exciting in a microwave?
If not, is there a gas (in liquid form) [sorry, I know that’s a nonsensical thing to say, but you know what I mean] that would give us some fun results?
Please don’t let our laboratory microwaves off the hook before we’ve properly put them through their paces.
user_hostile is correct about the Leidenfrost effect. The liquid N2 flash evaporates (instaboils) when it comes into contact with the floor (or anything at room temperature, which when compared to the liquid N2 is extremely hot). The layer of vapor then provides some insulation, protecting the rest of the droplet from boiling off so quickly.
One can do a simple experiment to see the onset of the Leidenfrost effect in water, with a pan (or an iron). Just heat it up, and throw water on it occassionally. As the pan heats, the water will evaporate more quickly; then, at a certain temperature, the ‘lifetime’ of the water on the pan will increase by a factor of around 5-10. This is caused by the Leidenfrost effect.
On the rotation issue–a symmetric diatomic molecule has only one mode. This is because the two “spin the bottle” modes are indistinguishable–if you think about it, you will see that any combination of these two modes is actually just this mode, about a different axis. The “common axis” mode doesn’t store any energy, so isn’t “excitable”.
Chronos also failed to mention that water molecules have permanent electric dipole moments, which is what causes them to be excited by the varying electric fields in a microwave. In addition to a candidate molecule having excitable modes, we need to have some way to excite those modes. I don’t know what kinds of easily generated fields would interact with a N2 molecule.
As for the microwave question, I’m not sure, so I don’t want to say. I’m guessing that Chronos’ microwave is an oldie. Mine doesn’t even spark with a fork inside.
One further point–the nitrogen inside the microwave, to my thinking, would boil slightly faster: the water vapor in the air inside the microwave would heat up, causing a generally warmer environment.
How long it would take for, oh, let’s say, one 7-ounce paper cup full of liquid nitrogen to boil off (evaporate?) at room temperature? And, for safety’s sake, let’s say that there’s no cover involved to keep the pressure in. Just one open cup sitting on a table in a regular room? Just curious…
CO[sub]2[/sub] will not turn to liquid at ordinary pressures. It will solidify instead (“dry ice”). It really would take a very strong sealed vessel to keep it liquid. Putting such a vessel in a microwave is Not A Good Idea.
You can really rule out most gases for various reasons. The only common atmospheric gas not yet ruled out is liquid Oxygen. And any casual experiments with LOX are strongly discouraged. It is a very dangerous stuff. They don’t use it in rockets for fun. Liquid Hydrogen likewise.
But then again, what about dry ice???
(I don’t believe microwaves are air tight. Since heating up regular, unfun, stuff produces a lot of vapor, some venting has to be provided.)
DOH!! I knew CO2 was dry ice at ordinary pressures (and very low temp, of course). Dumb dumb dumb.
Ok, but like you say ftg, we’ve got that dry ice sitting there. And a microwave just waiting to go to work. Let’s have some fun.
As for the sparking, in case it wasn’t clear from the report, this is, indeed, an ancient microwave under discussion, which has problems with even the simplest of tasks. There is nothing resembling a glass plate in the bottom, and even with a load, it still sometimes arcs. It does, however, still heat water, so I figured it should be adequately microwaveish to suffice for the experiment in question, and my office mates would probably lynch me were I to try something this idiotic with the new(er) microwave, which has not (yet) been observed to arc.
So if this microwave is turned on with nothing but air inside, it sparks? Why?
For the sake of science, I just took the glass plate and its holder out of the microwave down the hall. Hell, it even looks like it’s been cleaned in the last couple days, with no apparent food gunk inside. Turned it on, but, just as I expected, no sparks appeared.
As Chronos will surely point out in a more erudite manner, older microwaves do not have all the safety advances that newer microwave ovens contain. And when I say older, I mean before 1985 or so.
Older microwaves didn’t have all the internal shielding and used more power to produce the same amount of heat that newer microwaves can generate. That extra power leaks out and causes water particles in the air to super heat and ‘spark.’
Don’t you mean flash boil? A flash boil isn’t going to emit light–is it?
As for arcing, which will emit some wonderful UV, that requires the presence of an electic field which exceeds the breakdown voltage of the medium (re: a vacuum doesn’t count), and more importantly a chance to arc from one point to another. Since it’s not clear where the arcing is occuring within Chronos oven (e.g., in the air, off the wall, the “stirrer” blades) I’m not sure that theres enough edvidence that the flash boil is going to be the cause.
We got a microwave in 1978 and it lasted 12 years. Never saw any arcing with no load. I did stick a neon bulb in glass of water and watched the glow. Also did is with a regular light bulb with the screw socket stuck in a glass of water. It, too, glowed with some flashing internally. Not sure if the light bulb ever worked again though
My ex-wife still has the old Amana Radarrange that my grandfolks gave to us oh so long ago in storage.
This thing is so old, it can be used as a “Radarange”, or it has an alternate setting for convection oven. I’ve never used it as a convection oven because I’m not sure what one is.
If I can talk her into digging it out of storage, I may do the dry ice thing this weekend. I’ll get back to you.
