Name a substance that will change from liquid state to solid state on heating.
And remaining chemically unchanged? Nothing does that.
You could have your ceramics which change from a liquid structure to a solid structure, but that's with the formation of bonds on heating and all that.
The first thing that came to my mind was concrete, but that is a chemical reaction and doesn't really count.
Is it possible for some sort of solid solution to have a liquid phase at a lower temperature than a solid phase? E.g. one component of the solution precipitates out with increasing temperature while the other component turns to liquid?
It is possible, even for reversible transformations. It's only required that the high-temperature phase (the solid) has a higher entropy than the low-temperature phase (the liquid). As you can imagine, this is pretty unusual. I seem to remember that it's been demonstrated in some carefully designed polymer systems, though. Will look to see if I can find the details.
You read my mind.
Changes chemically :)
Ah, I found it: Plazanet et al., "Freezing on heating of liquid solutions," J Chem Phys 121:5031 p5031 (2004), discussed here. But a look at the subsequent literature indicates that the physics is still being worked out.
Interesting, although it sounds like that is still just a chemical reaction, although notably a reversible one.
Right, or put another way, a multi-component system (with additional factors such as mutual solubility) rather than a single-component system.
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