@freemo there used to br a website one could visit to find out what substances could decompose into- but it was more scientific-focused rather than hobbiest.

You wouldn't happen to know of such a resource I could plug stuff in and find out what it breaks down into?

@lucifargundam I know of no such site, not the way you want it, and im not sure such thing could really exist. Bear in mind, however, I'm far from an expert in chemistry, at best its a hobby for me..

So the issue I see here is that "decomposition" just means a chemical breaks down into constuent parts in some way and tends to imply there is no rearrangement of its parts with some reaction with another chemical. This is all fine and good however the results of decomposition depend greatly on the circumstances.

For example consider there are really several routes to decomposition: catalytic, UV break down, heat, electrolysis. Each one of these routes will usually produce entierly different decomposition products. Even then within a specific route the decomposition product can be almost anything as you tweak parameters, the temperature, frequency of UV, the catalyst chosen, as well as the pressure and even concentration of the reaction vessel will all have a huge effect. If any solvents are involved to facilitate the reaction (as would be the case with catalytic reactions usually) would also have a huge effect.

Take a really simple example, hydrogen peroxide which is just four atoms, two hydrogen, two oxygen. heat it up a little bit or use a catalyst and youll wind up with water and oxygen. Heat it up a great deal (as would also be the case with water alone) and it will decompose down to H2 and O2 separately (which is why if firemen try to put out extremely hot fires like magnesium fires with water it will cause explosions). Heat it up even more and you get elemental H and O separately rather than their diatomic form.

Now in the case of H2O2 there really arent too many break down options simply because you only have 2 different atoms so they can only combine in a limited number of ways. But we have literally just covered every single combination of H and O that can exist by describing all the decomposition routes of H2O2 via heating alone. Doable for such a simple molecule but for more complex molecules describing every route exhaustively becomes impossible.

The best you could hope for from such a database/site would be for it to describe a very limited set of common decompositions. For example it might just limit decomposition to various temperatures and what the most predominate results are and leave off the small % decomposition by products. But the cut off would be arbitrary in both the choice of temperature and the choice of % needed to list it as a decomposition.

For example pure water at room temperature will instantly "decompose" (we dont call this decomposition really) into H+ and OH- ions in very small concentrations. Most of the time its so small we ignore this even though some H+ ions will randomly neutralize and form H2, but the rate and concentration at which that happens is so small as to be pointless to think of it as existing at all. So in any reasonable % cut off we would lnot describe that as a natural decomposition at room temperature. But none the less it is there.

So yea long story short I dont think you will find what you are after. Best you might fine is sources like wikipedia that describe some very common decompositions and is no where near comprehensive.

@trinsec

@lucifargundam

By the way to make some limited attempt at actually giving you a useful answer. The only site I know that comes close to listing common decompositions consistently and in a sorta data formated way rather than wikipedia which is more of a teaching tool then I only know of one.

That would be PubChem, which basically lists almost every chemical imaginable, and all of its technical properties in a consistent and well laid out way. It almost always has a section on composition that lists several of the most common (though s we discussed not all) decomposition routes.|

I use PubChem almost every day when im doing chemistry and its really the only place that has anywhere near or approach an exhaustive list. I usually use it for figuring out what something is soluble in and what class of reactions it works well in.

Here is the PubChem page for hydrogen peroxide linking directly to its decomposition section as an example. The cool thing is I've found information on chemicals that google barely returns hits on and for which wikipedia pages dont even exist:

pubchem.ncbi.nlm.nih.gov/compo

@trinsec

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@freemo @lucifargundam @trinsec Aren't you looking for an MSDS repository? They sometimes describe what other substances can be produced in normal conditions, in interactions with things one expects the thing to possibly come in contact with.

@robryk

The MSDS is focused mainly on safety. If it talks about decomposition all it will usually be. Brief and focus on chemicals relevant to safey. Not as good a source for listing decomposition products as pubchem imo

@lucifargundam @trinsec

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