Apparently, this seemingly simple question doesn’t have easy answers. That’s what I conclude after reading a fascinating article by Kenneth Chang in the New York Times on the subject. I also learned that there are different forms of ice, characterised by different arrangements of the water molecules. Rather worryingly, scientists have so far discovered twelve forms, and it is suspected that there is at least one more form. I say worringly, because Ice Nine is the eponymous title of a doomsday story by Kurt Vonnegut (the story also goes under the title of Cat’s Cradle). Could Ice Nine be for real?
Why Is Ice Slippery?
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One response to “Why Is Ice Slippery?”
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Interesting – I’ll have to do some more reading to understand the two new(er) theories more.
Actually, many solids and compounds exhibit multiple solid forms at varying temperature and pressure. It’s a fundamental part of metallurgy and alloy formation, bringing a mixture of two (or more) metals to a particular state by understand the different solid phases it passes through as temp and pressure change. (It’s also the one cool fact that almost pulled me into materials science as a field instead of chemical engineering. Not that I use either much these days.)
On a separate but related note, one of the more interesting variations on ice I’ve come across are called gas hydrates – snowballs that burn.
Think about natural gas production from deep sea exploration. The temperature is low, the pressure is high, and methane (for example) is being piped out of the ground. Should a bit of water get into the pipes, at the right conditions, it can form ice – except instead of the usual crystal structure, it forms a football-like cage around the much smaller methane molecule. Furthermore, this acts like a seed crystal, so that once formed, other water molecules will latch on and expand the pattern. In the pipe, this can cause a total shutdown of production – the pipe is blocked by a giant ice slug on the ocean floor. Because of the high methane content, it is possible to set it on fire.
(see http://www.ruf.rice.edu/~hydrates/index.html for example)
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