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I was asked to look into this by Praxidicae regarding the accuracy of the image being used in the chembox. Science123!0, in an edit summary, links to Sigma Aldrich, which includes a near-identical image; this image is pretty darn close to ours, and since we're dealing specifically with potassium, the presence of the K+ kinda makes sense. I'm not really sure what's "wrong" here, but arguing over it in the edit summaries is less than useful, so Science123 if you could please explain that would be great. Primefac (talk) 19:59, 21 February 2021 (UTC)[reply]
The only thing I can potentially see is that it's not clear whether every carboxyl along the chain is as the potassium salt (as we illustrate it) vs some remaining as the protonated acid (Sigma-Aldrich calls their product "Poly(acrylic acid) partial potassium salt", emphasis mine). I don't know if there is a standard ratio, or different production methods/suppliers have different products, or it's simply a pH effect. That Sigma-Aldrich product does not specify a ratio (neither in the catalog nor as an entry in certificate of analysis), as if it's either highly variable or it's a standard that is just assumed. DMacks (talk) 17:08, 24 February 2021 (UTC)[reply]
I agree that this is what they are likely getting at, but in an earlier edit the editor gave a chemical formula that was just plain impossible for this polymer, so I am hesitant to follow them blindly. It is not uncommon for Wikipedia to illustrate idealized structures for polymers, which are usually too complex and variable to do otherwise (e.g. we don't show that a small proportion of nucleotides in DNA are methylated). Agricolae (talk) 18:39, 24 February 2021 (UTC)[reply]
I agree that our current image is the appropriate one for this article and also see some clear "not correct" details in various of their refs. DMacks (talk) 18:55, 24 February 2021 (UTC)[reply]
A late follow-up in case this comes up again: Let's not forget that ours is not the only illustration that is simplified. When salted, multiple potassiums will be coordinating each carboxylate anion and vice versa, and the anion's charge (and hence bonding) will be distributed between both oxygens, not one double-bonded uncharged and inert and the other single-bonded charged and forming a single ionic interaction with a single potassium/hydrogen, as the Sigma illustration shows. Any illustration is inherently inaccurate on some level. Agricolae (talk) 19:06, 6 March 2021 (UTC)[reply]
