Study Guides/Chemistry/K4[Fe(CN)6] — Potassium Ferrocyanide
Study Guide · Chemistry

K4[Fe(CN)6] — Potassium Ferrocyanide

K₄[Fe(CN)₆] is the chemical formula for Potassium Ferrocyanide, a coordination compound. It is a bright yellow crystalline solid and is an important reagent in chemistry labs and industry.

Question (Click to Flip)

What is the IUPAC name of K4[Fe(CN)6]?

Answer

The IUPAC name is Potassium hexacyanoferrate(II). The (II) indicates the +2 oxidation state of iron. In coordination compound naming: ligands first (hexa = 6, cyano = CN), then metal with oxidation state.

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Key Facts

The related compound K₃[Fe(CN)₆] is called Potassium Ferricyanide (iron is in +3 oxidation state). It forms a Turnbull's Blue precipitate with Fe²⁺ ions.

Key Details of K₄[Fe(CN)₆]

PropertyValue
Chemical NamePotassium Hexacyanoferrate(II)
Common NamePotassium Ferrocyanide
Central MetalIron (Fe)
LigandCyanide (CN⁻) — 6 ligands
Coordination Number6
GeometryOctahedral
Oxidation State of Fe+2
Hybridization of Fed²sp³ (inner orbital)

Finding Oxidation State of Fe: Let oxidation state of Fe = x K has +1 charge (4 K atoms = +4), CN⁻ has -1 charge (6 CN⁻ = -6), overall charge = 0 → 4(+1) + x + 6(-1) = 0 → x = +2

Uses and Tests

  1. Prussian Blue Test: K₄[Fe(CN)₆] reacts with Fe³⁺ ions to form a deep Prussian Blue precipitate. This is used to test for the presence of Fe³⁺ (ferric ions) in solution.
  2. Blueprint paper: Prussian blue was historically used in architectural blueprints (cyanotype process).
  3. Food industry: Used as an anti-caking agent in table salt (denoted as E536 in Europe).

Questions and Answers

What is the IUPAC name of K4[Fe(CN)6]?+

The IUPAC name is **Potassium hexacyanoferrate(II)**. The (II) indicates the +2 oxidation state of iron. In coordination compound naming: ligands first (hexa = 6, cyano = CN), then metal with oxidation state.

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