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Originally Posted by BananaStand
Huh? How do you sublimate a single molecule?
How else could it possibly occur? All chemical processes happen on the molecular / atomic level.
Originally Posted by BananaStand
Isn't the state of matter (solid/liquid/gas) related to the configuration of many molecules?
Yes and no. Each particle is in its state based on its "neighbor interactions." Specifically for water, if its movement is basically defined by hydrogen bonds, then it's an ice molecule. If it is frequently interacting with neighboring molecules, but not via stable hydrogen bonds (its specific neighbors are constantly changing), then it's liquid water. If its movement is largely unrestrained, aside from occasional (actually, well defined, here, despite the sound) interactions, then it is water vapor or steam.
Under certain conditions (not in a typical household freezer), the phases of matter can vary via a smooth transition, and not a sharp boundary.
Originally Posted by BananaStand
In other words, can you say that a single molecule is liquid, gas, or solid? And if so, wouldn't it always be solid?
No, there are tons of outlier cases, but for water near STP, this is well-defined for each particle, as I briefly stated above.
Originally Posted by BananaStand
Out where? I don't have any kind of fancy frost control gadgets on my freezer like Ong suggested.
You almost definitely have a frost free freezer. They haven't made the other kind in decades, AFAIK.
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BUT
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IDK what you've got.
You either have a freezer whose walls gather a couple of inches per year of frost, or you have a frost-free freezer.
Have you seen / do you recall those old freezers that would slowly crust over inside until they were a solid block of frost?
Originally Posted by BananaStand
Right, but why does it move first? In other words, why doesn't the sublimated particle re-condense immediately back onto the ice cube from whence it came?
The air in the freezer is ~200 K and zipping about real fast like. Interactions are rare on the length scales of the particles... many hundreds or thousands of particle diameters may be covered between collisions with another particle... but they are still common in time, 'cause the particles are still moving about rapidly and there's about 1 mole of particles per liter of air, so plenty of particles in the air in the freezer to interact with.
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