Yeah, but gallium is a single element, not part of a molecule, and the reason it expands upon transitioning to solid state is different than that of water.
But you’re right. It’s funky stuff, too. We used to play with it a lot in high school, i.e. throw it against a wall and watch it splatter apart, then sweep the bubbles back together, a foreshadowing of Terminator 2, I guess. In university, they wouldn’t let us have the stuff. I wonder why? :dubious:
Stranger
I don’t have a reference that displays density of water ice below 0[sup]o[/sup]C–that would be a highly unusual piece of information for most engineering thermodynamics/fluids mechanics applications–but according to my Fundamentals of Fluid Mechanics (Munson, Young, Okiishi), the density of water at boiling temperatue and standard atmospheric pressure is .9584 g/m[sup]m[/sup]. The density of water ice at 0[sup]o[/sup]C is .9999 g/m[sup]m[/sup]. Given that the rate of thermal contraction of solids is generally pretty low; probably low enough that by the time you got the ice cool enough to sink there would be all sorts of other heat transfer effects at the boundary (like the ice cube exploding into shards in thermal shock) that worrying about whether it would sink would be the least of your problems. I guess you could hypothesize some kind of density-neutral adiabetic boundary, but I don’t know how you’d go about creating such a thing in real life.
Also complicating the matter is that any real-world (or outside a highly sophisticated laboratory) water ice is going to have plenty of suspended matter and disolved gases that will further affect the density in difficult-to-predict ways. I’ve done a bit with ice buildup on aircraft control surfaces and determining the required heat to prevent buildup is something of a black art, based upon past knowledge, rather than an explicit or simulated solution to the idealized problem, 'cause we just can’t accurately model the composition and heat transfer characteristics of the ice on the wing.
It’s a good thing we have it, I suppose–like I said, it probably had a lot to do with the formation of life–but even though we understand its properties it’s a hard substance to really model accurately. And you shouldn’t pour your Irish whisky over it. 
Stranger
As an aside, I’ve never seen that notation before. I gather from context that it means “grams per cubic centimeter”, but how does m[sup]m[/sup] mean “cubic centimeter”?
I suppose because of possible hazards. Will the stuff come off on your hands? I suppose galium is at least mildly toxic.
Chemistry classes are a lot more safety conscious now than when I took Chemistry in 1946. There was no such thing as a fume hood in the Chem lab. In our little old repetion of Priestley’s heating of the oxide of mercury to produce oxygen guys were boiling the metallic mercury in the test tube and sniffing the result.
In Qualitative Analysis our recipe book said to take a little of the sample out in your palm and examine its physical characteristics. I took the lab in the summer and my palm was sweaty and the sample contained a red powder. A couple of days later a big purple spot appeared on my palm so I went to the professor, Prof. Jacob Cornog the old bastard, about it. He asked the number of the sample, looked in his book and said something to the effect that the blotch wasn’t surprising. The sample contained mercuric oxide and the spot was a mild case of mercuy poisoning.
Er…that should be g/m[sup]3[/sup]. :o :o
I thought I’d save time cutting and pasting the code, hence the double incidence. Preview doesn’t really help when you just skim over the highlights. :rolleyes:
Stranger
And now that I powerposted a correction, I realize I did the multiplication the wrong way. :rolleyes:
It should be 9584 g/m[sup]3[/sup] and 9999 g/m[sup]3[/sup]. (The original units were in English.)
Stranger
Still doesn’t work. Try 958**.4 kg/m[sup]3[/sup] and 999.**9 kg/m[sup]3[/sup]. Or you could have gone with Chronos’s suggestion of **0.**9584 g/cm[sup]3[/sup] and **0.**9999 g/cm[sup]3[/sup].
Quack. Quack. Quack-Quack. Bang!
I quack corrected.
I should really just work out the friggin’ unit conversions on paper, or fire up Mathematica and do them, instead of winging it mentally, 'specially at this hour. Even dumber, on the next page, they have the the same table in SI units. I was wondering why they only showed the table for English units in a modern (well, fairly recent) text. :smack:
Stranger