Editing Potassium ferrocyanide (section)

==Chemical reactions==
Treatment of potassium hexacyanidoferrate(II) with [[nitric acid]] gives H<sub>2</sub>[Fe(NO)(CN)<sub>5</sub>].  After neutralization of this intermediate with [[sodium carbonate]], red crystals of [[sodium nitroprusside]] can be selectively crystallized.<ref>{{cite encyclopedia | author = Seel, F. | title = Sodium nitrosyl cyanoferrate | encyclopedia = Handbook of Preparative Inorganic Chemistry | edition = 2nd | editor = Brauer, G. | publisher = Academic Press | year = 1965 | location = New York | volume = 2 | page = 1768 | lccn = 63-14307 | url = https://www.scribd.com/doc/27443280/Handbook-of-Preparative-Inorganic-Chemistry-Vol-2-2d-Ed-George-Brauer | access-date = 2017-09-10 | archive-date = 2010-03-07 | archive-url = https://web.archive.org/web/20100307011411/http://www.scribd.com/doc/27443280/Handbook-of-Preparative-Inorganic-Chemistry-Vol-2-2d-Ed-George-Brauer | url-status = dead }}</ref>

Upon treatment with [[chlorine]] gas, potassium hexacyanidoferrate(II) converts to [[potassium hexacyanidoferrate(III)]]:
:2 K<sub>4</sub>[Fe(CN)<sub>6</sub>] + Cl<sub>2</sub> → 2 K<sub>3</sub>[Fe(CN)<sub>6</sub>] + 2 KCl
This reaction can be used to remove potassium hexacyanidoferrate(II) from a solution.{{citation needed|date=April 2012}}

A famous reaction involves treatment with ferric salts, most commonly [[Iron(III) chloride]], to give [[Prussian blue]]. In the reaction with Iron(III) chloride, producing [[Potassium chloride]] as a side-product: 

3 K<sub>4</sub>[Fe(CN)<sub>6</sub>] + 4 FeCl<sub>3</sub> → Fe<sub>4</sub>[Fe(CN)<sub>6</sub>]<sub>3</sub> + 12 KCl

With the composition Fe{{su|p=III|b=4}}[Fe{{su|p=II}}([[Cyanide|CN]]){{su|b=6}}]{{su|b=3}}, this insoluble but deeply coloured material is the blue of [[blueprint]]ing, as well as on many famous paintings such as [[The Great Wave off Kanagawa]] and [[The Starry Night]].