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A solid chemical substance with a very high vaporization temperature can still produce potent smells at room temperature. What, then, produces smell, and could smelling some potent solid substance pose any danger, even if it hasn't vaporized at all?

Thanks!

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    $\begingroup$ Too smell something, molecules have to reach the nose. Sometimes it is not the molecules you expect, but there is always a molecule that triggers the response. $\endgroup$
    – Karsten
    Nov 30, 2022 at 23:18
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    $\begingroup$ There is no threshold temperature below which a substance does not evaporate. The rate decreases about exponentially with temperature, but does not reach zero. A nose is very sensitive to some molecules. $\endgroup$
    – Poutnik
    Dec 1, 2022 at 5:57
  • $\begingroup$ Additionally, there can be flying microparticles of fine dust. $\endgroup$
    – Poutnik
    Dec 1, 2022 at 6:11

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What is the difference between "smell/odor" and "vapor" of a substance?

It is assumed that the vapor of a given compound/element is the gas phase of the same pure compound/element. By condensing the vapor, you can obtain the same stuff in liquid or solid form.

Smell on the other hand is a human/animal perception. Although it is thought that plants can also smell. It is a biochemical interaction of that component with our smell receptors inside our nose. A very interesting example is that of a enantiomeric molecules. These are two different compounds with identical vapor pressure at a given temperature yet they smell very differently. One enantiomer of limonene smells like lemons and the other smells like oranges! Same elemental composition, same boiling point but a different orientation in space.

Your next point is how something which has very high pressure can still have a smell. For example, a very high boiling point metal like osmium (the name means smell) has a very bad odor, but this is not due to osmium metal itself but rather due to its very thin volatile oxide coating which forms on the metal.

Alternatively, there is another possibility which has been linked by Karsten in the comments. Metals can react with sweat components and body oils and make volatile smelly compounds. This is why we have a metallic odor, again this has nothing to with the metal vapor itself, but some organic compounds which have originated by the reaction of the metal with our fluids present on our skin in very very small amounts. Human nose is an excellent sensitive detector and it is used in analytical chemistry in something called Olfactory Chromatography! Perfume makers and food flavor chemists love this technique.

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A vapor is a gas made by evaporation of a liquid or of a solid (by sublimation). It may have an odor or not. Most substances in a gaseous state do have an odor. Water exists in a gaseous state, but it does not have any odor.

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    $\begingroup$ In the contexts I'm familiar with, a gas is not necessarily a vapor. "Vapor" is reserved for compounds below their boiling point, and above the boiling point the terminology is "gas". I'm sure it varies by field, but the first sentence of this answer I think is overly absolute. $\endgroup$ Dec 1, 2022 at 21:29
  • $\begingroup$ @electronpusher. You are right. I have rewritten my first sentence. $\endgroup$
    – Maurice
    Dec 1, 2022 at 22:37
  • $\begingroup$ In some sense, a gas is either vapour, either supercritical fluid. As vapour is defined as gaseous state at T < T_critical. $\endgroup$
    – Poutnik
    Dec 1, 2022 at 22:43
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    $\begingroup$ @Poutnik. You state that a gas is either vapor either ssupercritic fluid. Well ! A gas like $\ce{H2}$ or $\ce{O2}$ is neither a vapor nor a supercritical fluid. $\endgroup$
    – Maurice
    Dec 2, 2022 at 14:10
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    $\begingroup$ @Maurice OK, correction, He at p > 2.3 bar, H2 at p > 13 bar, O2 at p > 50.5 bar are supercritical fluids. $\endgroup$
    – Poutnik
    Dec 2, 2022 at 16:05

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