When An Essential Substance Used In Chemistry Turned Out Not To Exist
In 2018, a team of researchers attempting to investigate the use of sulfide solutions to reduce mercury emissions from alumina refineries made another, bigger discovery: an ion once considered an essential part of chemistry calculations simply does not exist
While investigating the use of sulfide solutions to reduce mercury emissions, the team began looking at the S2– ion.
While it does exist in various forms, it had been assumed that it exists as an aqueous solution, with water acting as the dissolving substance.
For decades, it was assumed that it existed in this form, S2–(aq).
However, the team used a Raman spectrometer, which uses scattered light to measure the vibrational energy modes of samples, and found to everyone’s surprise that despite their best efforts no S2–(aq) was detected.
“A simple chemical problem that defies the best that modern instrumentation can provide is rare nowadays,” the team wrote in their paper. “A widespread, ongoing misadventure in science is even rarer. However, both have happened over the assumed existence of the chemical species S2–(aq).”
According to the team, who wrote that the ion (in aqueous form) needs to be “comprehensively banished by the chemical community”, the mistake took place decades ago, and has been a part of chemistry research calculations ever since.
“It means that some simple chemistry calculations, often used to predict how sulfide minerals dissolve and react in water, are incorrect,” Dr Darren Rowland, co-author on the study, said in a statement at the time.
“Our recommendation to researchers and teachers is to not accept the existence of sulfide ion in aqueous solution, as there is no evidence for its existence.”
“We hope our results now take a firm hold in chemical calculations,” he added, “but time will tell.”
See more here iflscience.com
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K. Kaiser
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The observations are likely correct but, in my mind, are not really surprising.
The now claimed absence of an “S[^]-2 (aq) – ion” , in reality, is pretty meaningless.
This ion is, most likely is something as “S[^]-(OH[^]-1 (aq) – ion” or a similar one. Of course, the water molecule will bind, very lightly to a “naked” “S[^]-2” ion.
Sulfide solutions and/or gaseous hydrogen-sulfide have been used for centuries to analyze samples for the various metal components.
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Jerry Krause
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Hi K. ,
You began “The observations are likely correct” and I have not idea to what observations you are referring. However, any one does not know that S^2- does not exist in solution should have failed introductory chemistry. H2S is a weak acid and H
does ionize weakly to HS^- and certainly this ion is not a srong acid which ionizes completely to the divalent anion.
So when Dr Darren Rowland, states “It means that some simple chemistry calculations, often used to predict how sulfide minerals dissolve and react in water, are incorrect,” it is he, not chemists, who is wrong.
Have a good day
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Saeed Qureshi
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Thank you, Jerry, for your comment.
I also read the article with interest and wanted to read the original publication. But the original publication costs 42.50 pounds to download. So, I decided to avoid wasting my money.
My question was, if they did not find the S^-2, how was the S^-2 present, i.e., in what format? They would have seen what you, Jerry, described. But that would not have resulted in a “publication.”
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