I was asked and am wondering myself, what are materials that change color when molten? I could not find any examples online, but it really interests me. I would to get some examples which have one color when solid and a different one when liquid.

  • $\begingroup$ Related note: there are substances like oxygen - colourless when gas, light blue when liquid. $\endgroup$ – Gaurang Tandon Mar 3 '18 at 12:21
  • $\begingroup$ I think it could be reopened. Materials undergoing such a chromatic change do exist other than that in which the chance is merely linked to surface reflection properties and scattering. The OP might be interested in polydiacethylenes as a major example. In this case the change in colour can coincides with melting of a monomer that almost inevitably is coloured by polymer trace. Broadly, most of the material with extended pi system undergo thermo- and solvatochromism. $\endgroup$ – Alchimista Mar 6 '18 at 18:51
  • $\begingroup$ And the above holds for molten oligomers $\endgroup$ – Alchimista Mar 6 '18 at 18:53

It depends lad. You see... "Colour" is not exactly a thing. It is just photons reflecting off atoms. With that in mind, there is no property of "colour". A good example to help you realize why what you're asking has no certain answer, is every metal (ie. Iron). When molten, the colour will still be of a similar shade, but because of the heat, when I has just melted, it will have a radiant red similar to fire. Another example would be water. Water is see-through. But you can see ice better than water, and Steam can be spotted with fair ease. that doesn't mean the colour has changed.

Anyhow; to my knowledge there is no such thing as a material "Changing colours" when they change from Solid to Liquid.

Also, your note on Oxygen, is correct, but, when in gas form, it is never certain what colour an element is. The way we see gas is different to the way we see solids and liquids have for example Benzol. The refractive index in Benzol is greater to the atmosphere's...

edit: Look at the comments underneath

  • $\begingroup$ You are in fact correct. I looked it up and it seems to be as you say, I will however, ask my professor tomorrow, and tell you with certainty. Although I am 99% sure that you are indeed right, I want to clarify. If you are correct, would you wish me to remove my comment for It is not true information, or should I keep it along with our comments so people with the same thinking as me, see why they're wrong? $\endgroup$ – Vasilis Rafailidis Mar 6 '18 at 16:58
  • $\begingroup$ Vasilis all my comments were for op question. I will move there up. Sorry for the misplacing :) $\endgroup$ – Alchimista Mar 6 '18 at 18:28
  • $\begingroup$ And I am correct. Within the limit of what I said. $\endgroup$ – Alchimista Mar 6 '18 at 18:54

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