Iron periodate reagent

The iron periodate reagent is a detection reagent for lithium ions and is used in qualitative analysis . The reagent is freshly prepared for the detection of lithium, since the orthoperiodatoferrate (III) ions essential for the detection are only present in solution .

Presentation and composition

To prepare the reagent solution, potassium iodate is dissolved in a dilute potassium hydroxide solution and an aqueous iron (III) chloride solution is added. Potassium hydroxide is used in a large excess and iron (III) chloride in a deficit. The solution is thus composed of potassium ions , hydroxide ions , orthoperiodate ions , chloride ions and small amounts of orthoperiodatoferrate (III) ions. In a basic environment, hydroxide ions add to iodate anions to form periodate anions , which then complex with iron cations .

${\ displaystyle {\ ce {KIO4 + 4KOH + FeCl3 -> K2 [Fe (IO6)] + 3KCl + 2H2O}}}$

Formally, orthoperiodatoferrate (III) can be derived from orthoperiodic acid .

Detection of lithium ions

In the presence of lithium ions in a neutral or basic solution, a white-yellow precipitate with an indefinite composition falls out:

${\ displaystyle {\ ce {K2 [Fe (IO6)] + 2Li + -> Li2 [Fe (IO6)] v + 2K +}}}$

Similar precipitates can also produce ammonium ions , divalent metal cations, and high concentrations of sodium ions when the solution is heated.

Individual evidence

↑ ^a ^b ^c G. Jander, E. Blasius: Textbook of analytical and preparative inorganic chemistry . Ed .: Joachim Strähle, Eberhard Schweda. 16th edition. S. Hirzel Verlag, Stuttgart 2006, ISBN 978-3-7776-1388-8 , p. 384 .
↑ Entry on periodates. In: Römpp Online . Georg Thieme Verlag, accessed on June 5, 2017.
^ AF Holleman , N. Wiberg : Inorganische Chemie . 103rd edition. Volume 1: Basics and main group elements. Walter de Gruyter, Berlin / Boston 2016, ISBN 978-3-11-049585-0 , p. 527 (Reading sample: Part A - Basics of the chemistry of hydrogen. Google book search ).

[Jander_Blasius-1] G. Jander, E. Blasius: Textbook of analytical and preparative inorganic chemistry . Ed .: Joachim Strähle, Eberhard Schweda. 16th edition. S. Hirzel Verlag, Stuttgart 2006, ISBN 978-3-7776-1388-8 , p. 384 .

[2] Entry on periodates. In: Römpp Online . Georg Thieme Verlag, accessed on June 5, 2017.

[3] AF Holleman , N. Wiberg : Inorganische Chemie . 103rd edition. Volume 1: Basics and main group elements. Walter de Gruyter, Berlin / Boston 2016, ISBN 978-3-11-049585-0 , p. 527 (Reading sample: Part A - Basics of the chemistry of hydrogen. Google book search ).