Talk:Potassium ferrocyanide

Ferroxyl indicator solution
I beleieve there is an error concerning "ferroxyl indicator solution". One of two facts are possibly wrong: 1. That ferroxyl indicator solution contains both potassium ferrocyanide and phenolphthalein, or  2. ferroxyl indicator solution turns blue in the precence of Fe+2 ions.

1. It could possibly be that it contains potassium ferricyanide instead of ferrocyanide, because the potassium ferrocyanide already contains Fe+2 ions. These ferrous (Iron(II) Fe+2) ions should therefore be selfdetecting. 2. Or possibly the ferroxyl indicator solution actually indicates the presence of ferric (Iron(III) Fe+3) ions when it turns blue.

I believe that the latter is correct because if the indicator can detect the presence of rust it detects ferric ions. Rust is iron oxide, Fe2O3, thus seen as (Fe+3)2(O-2)3 OR [Fe2]+6[O3]-6 with the respective net and gross equivalent ionic charges.

In conclusion I beleive that ferroxyl indicator solution actually contains both potassium ferrocyanide and phenolphthalein, however it is an indicator for Fe+3 (ferric Iron(III)) ions.
 * I would agree, and I have edited the article accordingly: I will try to find a reference to be sure. Physchim62 (talk) 08:03, 23 February 2006 (UTC)


 * Your fist conclusion is actually the correct one. Ferroxyl indicator contains potassium ferricyanide (AKA potassium hexacyanoferrate(III), which turns blue in the presence of Fe2+ ions. I am going to move the paragraph reffering to the ferroxyl indicator to the potassium ferricyanide article. --Ngunn 22:45, 20 September 2006 (UTC)


 * Ferrocyanide reacts with Fe2+ to make Prussian white, which is unstable in the presence of oxygen or water and will more or less instantly oxidize to make Prussian blue - so it could certainly use ferrocyanide as a test for Fe2+. —Preceding unsigned comment added by 128.227.82.171 (talk) 19:26, 11 April 2009 (UTC)

No free hydrogen cyanide generated with acid
When Ferrocyanides are treated with strong acids Ferrocyanic Acid can be isolated as a separate substance and in "super acids" the Ferrocyanide complex exists in its protonated form. Author is confused because at very strong acid concentrations, free Hydrogen Cyanide is rapidly protonated then hydrolyzed to Formic Acid and Ammonium ions. If Ferrocyanide was so unstable as to release Cyanide on acidification then it would react with Chlorine to form Cyanogen Chloride. The CRC shows the dissociation constant of [Fe][CN] ~ 10^33 for Ferrocyanide. (Note aqueous acid has pH limitation). 2001:4898:80E8:ED31:0:0:0:2 (talk) 07:47, 15 June 2015 (UTC)
 * Just tried the HCl reaction with 6M HCl and Sodium Ferrocyanide = no Hydrogen Cyanide odor.2001:4898:80E8:ED31:0:0:0:3 (talk) 07:50, 15 June 2015 (UTC)
 * If you think that the article is incorrect, then go ahead and fix the problem. --Smokefoot (talk) 12:22, 15 June 2015 (UTC)

Colour and Texture Difference Between Anhydrous and Hydrated Potassium Ferrocyanide
According to some sources, anhydrous Potassium Ferrocyanide (Anhydrous Potassium Hexacyanoferrate (II)) is closer in colour to being a pale white powder than the crystalline Potassium Ferrocyanide Trihydrate (Potassium Hexacyanoferrate (II) Trihydrate). Further, is it true that, to obtain the Anhydrous Potassium Ferrocyanide salt, one merely has to place the Hydrated salt into an oven at a high temperature to dehydrate it? In summa, the anhydrous salt is meant to be white-pale-yellow and the hydrated salt is much more pale yellow.

ASavantDude (talk) 17:59, 8 January 2016 (UTC)

Melting point is definitely wrong
Melting point is well above the currently listed 70C. — Preceding unsigned comment added by 173.49.202.138 (talk) 01:06, 13 February 2016 (UTC)