@zleap

Its a complex question that has less to do with how far smell travels and more to do with the sensativity of the nose and chemical "noise"

So first off, no, aromatic compounds, despite the name, are not (always) compounds that are smelly. Its just a very poorly named property that means a compound has what we call an "aromatic ring" which is a 6 carbon ring witb alternating single and double bonds. They have nothing to do with smell.

So back to the question, smell effectively travels infinitely far given enough time, assu.ing we coubt even a single atom as suffecient. So in reality how far a smell travels has more to do with the sensativity of the nose and the diffusion rate of the compound.

Take humans and the geosim compound as an example (the smell of wet dirt after a rain). Humans are extraordinarily sensative to this compound. Just 5 atoms in a trillion is enough for us to detect it. For comparison mercaptan, the smell of grapefruit, is 1600 atoms per trillion threshold.

Now distance would depend on wind, time, and temperture effecting diffusion. Its complex but on a windy day a few atoms can make quite a distance im sure.

As to some real world numbers, bears can smell most cood at approximately a 20 mile distance.

@oldrawgabbit @krypt3ia

@freemo @oldrawgabbit @krypt3ia

Thanks for this, I was kind of linking Aromatic with Aroma, so thanks for clearing that up too. So when we add HS to CH_4 this is because humans can't pick up CH_4,
Interesting subject matter though, The fact bears can smell food from a distance is why we were not allowed to keep food in our cabins on summer camp ( canada 2006 ). And I guess if camping food needs to be stored outside the main tent or in such a way that animals can't smell it, I don't think you would want bears in your tent.

@zleap @oldrawgabbit @krypt3ia

Yea some things we cant smell at any concentration.

When aromatic compounds were first discovered it was thought it was linked to smell thus given that name early on. Even once we realizee it was unrelated to smell the name stuck.

A decent portion, like 80 percent if i had to guess, do have a smell.

@freemo @oldrawgabbit @krypt3ia

Reminds me of electricity, there is conventional flow (positive to negative) then we found out that electrons were negative, and that really messed up a lot of circuit diagram and teaching so if I understand it we left that as is, but we do need to look at electron flow in other situations. Usually when it comes to semi-conductors.

@zleap @oldrawgabbit @krypt3ia

In electricity it isnt quite as wrong as it seems. I mean hour right the electrons arw the only thing with mass moving. But we actually can valjdly make the case that positive charges move, we call the. "Electron holes"

@freemo @oldrawgabbit @krypt3ia

I have a book here on electronics that explains electron holes nicely, using Boron-Silicon and Silicon-Phosphorous as the example at the time.
If I get this correctly it is due to the difference in electrons in shells so Boron has one less than Silicon ( p-type (positive)) and Phosphorous has one more (n-type (negative)) so when combined in a process the book called doping the properties are combined, when ntype and ptype are then put together you get things like transistors.

@zleap @oldrawgabbit @krypt3ia

It appliea even to simple conductors too. You can think of it as electrons moving in one direction or as holea in the opposite.