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Brain&Force
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The novel and uncharacterized compounds thread.
So many compounds lack information that can be found in basic references such as Wikipedia.
If you're looking for something to do in your spare time, why not make and investigate some of these compounds? Many of them can be made easily from
lab chemicals and not all of them are dangerous.
The criteria for inclusion in the uncharacterized compounds list includes:
- There's no good reason the compound hasn't been researched thoroughly (i.e. requires no special handling and is not prohibitively expensive,
something that can be done in your home/backyard)
- No Wikipedia article, or article marked as stub.
- Its Wikipedia article is about an application rather than the compound's chemistry.
- No research papers on the compound
- Any of this information missing or unknown:
-Color or other appearance information that could be determined with a photo
-Melting/boiling points
-Density
-Solubility in water (if applicable) or other solvents
-Air stability
Here are some compounds that meet this definition and warrant further study.
Iron(II) iodide - The Wikipedia article is a stub.
Chromium dioxide - although its article does exist, and is not a stub, it doesn't have any information about its chemistry; most of the article is
about its application in cassette tapes.
Samarium(II) iodide - same as above, though it's used as a reducing agent in labs. Its air stability and density are not known. (This may be harder to
work with.)
Most lanthanide compounds.
Compounds without images on Wikimedia Commons cannot be considered uncharacterized, but it would be a good idea to make and submit any images you have
of these compounds for article improvement.
I hope this can kickstart some novel research here at ScienceMadness!
At the end of the day, simulating atoms doesn't beat working with the real things...
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Tdep
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What credibilities must one have to create a wikipedia page or add a picture of a chemical to an existing wikipedia page?
I was planning to make some terbium sulphate some time, and noticed that it didn't have a wikipedia page (although there are some picture of it on the
terbium page). Would my experiences with the chemical as an amateur home chemist be any sort of use to write up an article, if I'm not all that
trustworthy?
Edit: There's a terbium sulphate article in german, not english. Strange. But the question still remains. Isn't no information better than
untrustworthy information, especially when it comes to chemistry?
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blogfast25
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Quote: Originally posted by Tdep  | What credibilities must one have to create a wikipedia page or add a picture of a chemical to an existing wikipedia page?
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I don't know but just because Wiki doesn't provide the information doesn't mean it isn't available somewhere.
Before people go off on wild goose chases, I suggest they familiarise themselves with methods of literature research, as outlined in the guidelines of
the forum:
http://www.sciencemadness.org/talk/viewthread.php?tid=19143#...
[Edited on 8-12-2013 by blogfast25]
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bismuthate
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blogfast has a point, not everything is from wiki.
The big problem I see is that the list could be incredibley long. Other than that I love the idea!
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Pok
potassium Prometheus
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Wikipedia is an encyclopedia. And this is nothing but a collection of quotations verified by references (at least it should be so).
It's useless and dangerous to write something in wikipedia about density or solubility that was measured by a home chemist. Dangerous because they are
not reliable. Unfortunately the solubility table at wikipedia is not verified by references. This table is nearly completely useless because you can't
trust it. In this case wikipedia destroyed knowledge that was reliable in old "real" encyclopedias!
Photos of chemicals would be a good idea. They are difficult to find in the standard literature. But they also don't contain much information that is
relevant for a chemist.
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blogfast25
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Pok:
I disagree somewhat: dismissing Wiki's entire solubility table on the basis of it not being referenced seems wasteful to me. References data aren't
necessarily correct either: different authorative sources sometimes present different values too.
Also, densities or solubilities measured by a home chemist aren't by definition unreliable.
As regards photos, why would they be more reliable than any other data presented by home chemists?
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kristofvagyok
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| Quote: Originally posted by Pok | | Photos of chemicals would be a good idea. They are difficult to find in the standard literature. But they also don't contain much information that is
relevant for a chemist. |
We have several thousand chemicals in the university, if anyone would like to make a photo from them it would be a several month long project and it
would be almost totally useless.
Why? Depending on the source, impurities, crystal forms a compound could look really different. A great example 5-bromo-2-carboxyethyl-indole. This
was the first chemical what I have made and every time I made it, it looked really different. First it was a brown gunk, just like as they described
in the patent what I have worked from (it contained none of the title compound), second turn it was a beautiful orange crystalline solid and third
time it was a white foam like crystalline solid. So if I would take a photo from the first product and submit it as "it should look like this", than
everyone who makes this and gets a nice crystalline stuff, would be disappointed.
In case of inorganic compounds, what have characteristic colors and crystal form like copper, cobalt ect. containing chemicals, it could be a good
idea, but for the 99% of the chemicals, especially at the organics, it is totally useless.
I have a blog where I post my pictures from my work: http://labphoto.tumblr.com/
-Pictures from chemistry, check it out(:
"You can’t become a chemist and expect to live forever." |
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Pok
potassium Prometheus
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| Quote: Originally posted by blogfast25 | | I disagree somewhat: dismissing Wiki's entire solubility table on the basis of it not being referenced seems wasteful to me. |
This table contains many mistakes. So it can't be used as a reliable source of information. When planning an experiment which depends on the
solubility of one substance you can't simply trust these values given there. So you could only use this table as a basis for further research on the
solubility. But if no references are given it's not even useful as a basis for literature research! The only useful thing about this table is that you
can say that the values for one substance are "correct with a probability of 90 %".
One example: I once wanted to precipitate caesium out of solution. I searched at the table for the least soluble caesium salt which is CsBrO3 (at 0
°C). So I took the expensive sodium bromate to precipitate the Cs. But later I noticed that this value is wrong. It's 10 times higher in reality
(which makes absolutely sense if you plot the values against temperature!). Cheap sodium chlorate would have done a similar good job. 
Photos are not per definition more reliable. But you don't need much equipment and knowledge to make a photo. But that's the case for real
measurements like density or solubility. That's why it's at least "more probable" that photos made by home chemists show the truth than measurements
made by a home chemist.
@kristofvagyok: OK. I agree.
[Edited on 8-12-2013 by Pok]
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blogfast25
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Pok:
Your opinion may be a little coloured by that bad experience, whereas mine maybe coloured by a recent positive one, where the tabled values were in
perfect alignment with my experiment.
Whatever tabled values you find anywhere, caution and scepticism are always good to have at hand.
And I agree with Kristov on the photos: taking good, clear shots of representative samples of reasonably pure compounds is really no sinecure. I think
they're more useful as evidence (but not proof) that a reporting experimenter has actually done what he claims. And we all like a good picture...
[Edited on 8-12-2013 by blogfast25]
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kristofvagyok
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-sorry for the large image, but this is pretty informative I think(:
I have a blog where I post my pictures from my work: http://labphoto.tumblr.com/
-Pictures from chemistry, check it out(:
"You can’t become a chemist and expect to live forever." |
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Brain&Force
Hazard to Lanthanides
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Whoa! I did not expect to get a lot of responses. Thanks for the critiques; I'll address them individually.
Tdep: The point I had in mind was not to edit Wikipedia - it's to expand the member publications section (which is painfully lacking) and just start
some research. Any information gathered here would be useful for forum users' future reference.
I would like a ScienceMadness wiki, but that's a different thread...
blogfast25: The main intent is to streamline the search process, but there is much to be found in the literature. Also, users can contribute and add
more information, especially about reactions which haven't been attempted yet.
Pok: Taking one data point is prone to error, but the idea is to aggregate data points and average. That should give a much better result. If
ScienceMadness could store some basic data gathered by members about simple compounds, I'd use it rather than Wikipedia.
kristofvagyok: You do have a point about photos being a big endeavor, especially with organics. But as I mentioned earlier, the point is to aggregate
and average. Photos can be essential to certain projects - just look at the neodymium sulfate thread. Images could be uploaded to Wikimedia Commons as well.
Also, I was hoping this project could cover simple inorganic compounds first, then move on to more complex ones as well as organics.
By the way, where did you find the comic? I can't find it in the xkcd archives.
Feel free to add in more compounds that you think are worthy of investigation. Here are some others I have thought of:
Lower vanadium oxides (specifically VO and VO2)
Selenium trioxide
Permanganates of heavier alkali/alkaline earth elements
At the end of the day, simulating atoms doesn't beat working with the real things...
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bismuthate
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copper permanganate
pretty much every
(PH4)- compound
many azides also remain unresearched
I could iust keep on going for pages upon pages.
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ScienceSquirrel
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I have done several crystallisations using the Wikipedia solubility table data and found that they worked OK.
There are lots of mistakes everywhere.
Last week I read a recipe that said to boil potatoes for 5 minutes, the writer meant 25 minutes at least. Potatoes boiled for 5 minutes are still very
hard.
Scepticism is required when reading everything.
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blogfast25
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I've noticed that occasionally the values in the table and the values in the compound entries are very different, indicating multiple editors
consulting different sources. But that happens outside of Wikipedia too.
[Edited on 9-12-2013 by blogfast25]
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learningChem
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| Quote: | | Wikipedia is an encyclopedia. And this is nothing but a collection of quotations verified by references (at least it should be so).
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I wonder where you got that idea?
http://www.merriam-webster.com/dictionary/encyclopedia
" a work that contains information on all branches of knowledge or treats comprehensively a particular branch of knowledge usually in articles
arranged alphabetically often by subject "
"Medieval Latin encyclopaedia course of general education, from Greek enkyklios + paideia education"
[Edited on 10-12-2013 by learningChem]
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bfesser
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Why not let <a href="http://en.wikipedia.org/wiki/Wikipedia" target="_blank">Wikipedia</a> <img src="../scipics/_wiki.png" /> tell
you what it is?
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learningChem
Hazard to Others
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I don't care what 'wkipedia' says about 'wikipedia'. I'm commenting on what an encyclopedia is.
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blogfast25
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Yawn.
Wikipedia is an encyclopedia, really not too different from most others. The fact that you don't seem to like it much doesn't change that fact.
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bfesser
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<strong>learningChem</strong>, close-mindedness is certainly not a good trait for a scientist, and is quite unbecoming of a science
hobbyist. (Besides, I wasn't particularly meaning to address your reply, but the topic as a whole.) Lighten up; you'll live longer, and you might
just learn something along the way.
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learningChem
Hazard to Others
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I'm pointing out that an encyclopedia is not a collection of 'sourced quotes' - encyclopedias can have and do have original content. I'm not sure how
pointing this (admitedly off-topic) fact shows that I'm close minded.
But thanks for the friendly advice anyway.
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smaerd
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Wikipedia does use web-sites for references. Those tend to be the more scrupulous things. As much as I trust my fellow scientists doing work at home
it would only seem fair that any data gathered and shared on wikipedia were cataloged and referenced in the form of a prepublication or similar. So a
reader can see the method, any criticism from fellows, and maybe even join SciMad to ask further questions or share their results. In that clause I
feel that adding amateur experimental data to wikipedia would actually be far more informative then a published article. So much is left out in papers
and publications that isn't on message boards. In a lot of ways I feel amateur experimentalism is science at it's purest when done correctly.
Things such as solubility data are not as known as I wish they were, especially for solvents outside of water. Color isn't something I'm terribly fond
of for many reasons (isomorphs, hydrates, contamination, poor characterization). Density, sure but be mindful of significant figures. Solubility is
fine, most people only need a ball-park anyways (except maybe physical chemists...), so long as the experiment is conducted properly. pKa's why not,
just include information about the resolution with replication. Melting-point range can't really go too wrong there... Pictures, who doesn't love a
good picture  ?
I like the idea, I've tried adding things to wikipedia articles before but my submissions were rejected because I couldn't figure out how they did
their referencing... There are thousands of compounds that are rich in literature which don't have wiki pages. I find it a bit annoying because
wikipedia can be a cursory launch point for research.
[Edited on 15-12-2013 by smaerd]
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Bezaleel
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| Quote: Originally posted by smaerd | | Wikipedia does use web-sites for references. Those tend to be the more scrupulous things. As much as I trust my fellow scientists doing work at home
it would only seem fair that any data gathered and shared on wikipedia were cataloged and referenced in the form of a prepublication or similar. So a
reader can see the method, any criticism from fellows, and maybe even join SciMad to ask further questions or share their results. In that clause I
feel that adding amateur experimental data to wikipedia would actually be far more informative then a published article. So much is left out in papers
and publications that isn't on message boards. In a lot of ways I feel amateur experimentalism is science at it's purest when done correctly.
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I feel very similar. I've had many thoughts on how practical data for home experimentors would need to be compiled, but I haven't found an answer yet.
On solubility data
Take the solubility data from wiki as an example. When I added the values from Gmelin for praseodymium sulphate, the first thing I was confronted with
was that I had two lists: one for the anhydrous substance, and some for hydrated species. I decided to focus only on the hydrated species, and only on
that hydrate which you obtain after crystallisation from solution under standard conditions.
Next are the values. The CRC handbook, for example, lists the solubilities as grams of the zero-hydrate per 100 grams of water, also for the hydrated
species. That's the first reason I decided to explicitly add the crystal water as part of the formula for my entry.
Secondly, some water-free compounds have a lower solubility than the hydrated salt (per gram of water free substance, soluble in 100g of water), or
the other way around. I then realised that this is one big reason for differences and potential misunderstanding of solubility data.
My conlcusion was that wiki's solubility table had simply not been set up with all these complications in mind. And for that reason, the data
contained in it should be used with caution.
| Quote: Originally posted by smaerd | Things such as solubility data are not as known as I wish they were, especially for solvents outside of water. Color isn't something I'm terribly fond
of for many reasons (isomorphs, hydrates, contamination, poor characterization). Density, sure but be mindful of significant figures. Solubility is
fine, most people only need a ball-park anyways (except maybe physical chemists...), so long as the experiment is conducted properly. pKa's why not,
just include information about the resolution with replication. Melting-point range can't really go too wrong there... Pictures, who doesn't love a
good picture ?
[Edited on 15-12-2013 by smaerd] |
Agreed, especially the first point you mention here. And I often have great difficulty finding these data. Even big works like my favorite Gmelin are
incomplete. For example, I couldn't find any solubility data on [Ni(en)3]OH2 in it, whereas I can hardly believe it hasn't been researched.
In short, I'd very much like to have data pages composed by a mixture of literature data and amateur scientists' results.
Besides, a good initiative started a few months back, was bfesser's creation of the topical compendium. This gives at the very least an overview of
what experimenting has been done and posted here on the forum, categorised per compound.
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blogfast25
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| Quote: Originally posted by Bezaleel | My conlcusion was that wiki's solubility table had simply not been set up with all these complications in mind. And for that reason, the data
contained in it should be used with caution.
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The 'complications' exist largely in your mind only. Solubility should always be expressed as the anhydrous salt: in solution what matters only is the
mole fraction of salt and the mole fraction of water because you can't distinguish between the solute and the solvent, it's one phase. And if you
actually want to use solubility data for practical purposes it's mole fractions that matter to calculate crystallisation yields and such like
(although it can be done on a mass basis also).
Using the hydrate as a basis really complicates matters needlessly. For starters: which hydrate? Look at sodium carbonate e.g.: a whole raft of
different hydrates.
I think you don't understand very well how two phase systems like these work and shouldn't be let near any published solubility table.
[Edited on 16-12-2013 by blogfast25]
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woelen
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I agree that using hydrated salts needs precise specification of which hydrate, but I do not agree that every thing needs to be renormalized to
anhydrous form. Sometimes the anhydrous form does not even exist or it is completely insoluble, because of the totally different structure. An example
is anhydrous VOSO4. This compound is totally insoluble and does not react with water, not even with water which contains a lot of strong acid.
Anhydrous VOSO4 is some grey inert polymeric and covalent compound, while VOSO4.5H2O is a blue salt and easily dissolves in water.
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blogfast25
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| Quote: Originally posted by woelen | | Sometimes the anhydrous form does not even exist or it is completely insoluble, because of the totally different structure. |
Whether the anhydrous form actually exists or is stable is irrelevant here. Many of these compounds don't have stable anhydrates. For
solubility/crystallisation calculations that has no consequences.
Nor is this a 'renormalisation' in any sense of the word.
The two phase/temperature system is what it is: it dictates which hydrate is in equilibrium with which saturated solution of which mole fractions of
solute and solvent.
In some instances listing solubility of a specific hydrate can be useful, if temperature is specified.
Re. stability, lots of hydrates aren't very stable either: cases of efflorescence or deliquiesence galore!
[Edited on 16-12-2013 by blogfast25]
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