Potassium trioxalato ferrate (III)

Structural formula
General
Surname	Potassium trioxalato ferrate (III)
Molecular formula	K 3 [Fe (C 2 O 4 ) 3 ]
Brief description	green solid (trihydrate)
External identifiers / databases
CAS number 5936-11-8 (anhydrous) 14883-34-2 (trihydrate) EC number 238-954-7 ECHA InfoCard 100,035,398 PubChem 9932777 Wikidata Q2479795
properties
Molar mass	437.20 g mol −1
Physical state	firmly
density	2.133 g cm −3
Melting point	230 ° C
solubility	slightly soluble in water (trihydrate)
safety instructions
GHS labeling of hazardous substances Caution H and P phrases H: 302-312 P: 280-301 + 330 + 331-302 + 352-312
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Potassium trioxalato ferrate (III) is a chemical compound with the formula K ₃ [Fe (C ₂ O ₄ ) ₃ ]. It often occurs as the trihydrate K ₃ [Fe (C ₂ O ₄ ) ₃ ] · 3 H ₂ O. Both are crystalline compounds with a light green color. The compound is a salt of ferric oxalate anions [Fe (C ₂ O ₄ ) ₃ ] ³⁻ and potassium cations K ⁺ . The anion is a transition metal complex consisting of an iron atom in the + III oxidation state and three bidentate oxalate ions C ₂ O ₄ ²⁻ . Potassium acts as a counterion and balances the triple negative charge of the complex . In solution , the salt dissociates to form the ferrioxalate anion [Fe (C ₂ O ₄ ) ₃ ] ³⁻ , which takes on a fluorescent green color.

Extraction and presentation

An aqueous solution of iron (III) chloride is reacted with potassium oxalate to form potassium trioxalato ferrate (III) and potassium chloride:

${\displaystyle {\ce {FeCl3 + 3 K2C2O4 -> K3[Fe(C2O4)3] + 3 KCl}}}$

properties

Photoreduction

The ferrioxalate anion is sensitive to light and to higher energy electromagnetic radiation , including X-rays and gamma rays . The absorption of a photon causes the decomposition of an oxalate to carbon dioxide CO ₂ and the reduction of the iron (III) atom to iron (II).

use

Chemistry class

The synthesis and thermal decomposition of potassium ferrioxalate is a popular task for high school and university students as it includes the chemistry of transition metal complexes, visually observable photochemistry, and thermogravimetry .

Trihydrate green crystals

Further

The compound is used in chemical actinometry to measure luminous flux.

Individual evidence

1. ↑ ^{a b c d e f} data sheet Potassium trioxalatoferrate (III) trihydrate from AlfaAesar, accessed on June 3, 2019 ( PDF )(JavaScript required) .
2. ↑ J. Ladriere: Mössbauer study on the thermal decomposition of potassium tris (oxalato) ferrate (III) trihydrate and bis (oxalato) ferrate (II) dihydrate. In: Hyperfine Interactions . 70, 1992, pp. 1095-1098, doi: 10.1007 / BF02397520 .
3. ↑ A. Saritha, B. Raju, M. Ramachary, P. Raghavaiah, KA Hussain: Synthesis, crystal structure and characterization of chiral, three-dimensional anhydrous potassium tris (oxalato) ferrate (III) . In: Physica B: Condensed Matter . tape 407 , no. 21 , November 2012, p. 4208–4213 , doi : 10.1016 / j.physb.2012.07.005 .
4. ↑ Benjamin J. Abram, Dr. Richard Nafshun: Introduction To The Lab Manual . In: Apparel Quality Lab Manual . Fairchild Publications, ISBN 978-1-5013-0327-2 ( bloomsburyfashioncentral.com [accessed May 30, 2019]).
5. ↑ A new sensitive chemical actinometer - II. Potassium ferrioxalate as a standard chemical actinometer . In: Proceedings of the Royal Society of London . Series A. Mathematical and Physical Sciences . tape 235 , no. 1203 , June 12, 1956, ISSN  2053-9169 , p. 518-536 , doi : 10.1098 / rspa.1956.0102 .
6. ^ John Olmsted, Preparation and analysis of potassium tris (oxalato) ferrate (III) trihydrate: A general chemistry experiment . In: Journal of Chemical Education . tape 61 , no. December 12 , 1984, pp. 1098 , doi : 10.1021 / ed061p1098 .