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Potassium Ferricyanide
Potassium Ferricyanide laboratory grade manufacturer, supplier and exporter.
Potassium ferricyanide is also one of two compounds present in ferroxyl indicator solution (along with phenolphthalein) which turns blue (Prussian blue) in the presence of Fe2+ ions, and which can therefore be used to detect metal oxidation that will lead to rust. It is possible to calculate the number of moles of Fe2+ ions by using a colorimeter, because of the very intense color of Prussian blue Fe4[Fe(CN)6]3.
SAFETY :
Potassium ferricyanide has very low toxicity, its main hazard being that it is a mild irritant to the eyes and skin. However, under very strongly acidic conditions, highly toxic hydrogen cyanide gas is evolved, according to the equation:
6 H+ + [Fe(CN)6]3− → 6 HCN + Fe3+[9]
The reaction with hydrochloric acid is as follows:
6 HCl + K3[Fe(CN)6] → 6 HCN + FeCl3 + 3 KCl
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IUPAC name : Potassium hexacyanoferrate(III)
Identifiers
CAS number 13746-66-2 Y
PubChem 26250
RTECS number LJ8225000
Properties
Molecular formula C6N6FeK3
Molar mass 329.24 g/mol
Appearance deep red crystals
Density 1.89 g/cm3, solid
Melting point 300 °C, 573 K, 572 °F
Boiling point : decomp.
Solubility in water 330 g/L ("cold water")
464 g/L (20°C)
775 g/L ("hot water")[1]
Solubility slightly soluble in alcohol
soluble in acid
soluble in water
| Physical state and appearance | Solid. (crystalline powder.) |
| Odor | Not available |
| Taste | Not available |
| Molecular Weight | 329.25 g/mole |
| Color | Red |
| pH (1% soln/water) | Not available |
| Boiling Point | Not available |
| Melting Point | Decomposes |
| Critical Temperature | Not available |
| Specific Gravity | 1.85 (Water = 1) |
| Vapor Pressure | Not applicable |
| Vapor Density | Not available |
| Volatility | Not available |
| Odor Threshold | Not available |
| Water/Oil Dist. Coeff | Not available |
| Ionicity (in Water) | Not available |
| Dispersion Properties | See solubility in water |
| Solubility | Soluble in cold water |
| Stability | The product is stable |
| Instability Temperature | Not available |
| Conditions of Instability | Heat, light, incompatible materials |
| Incompatibility with various substances | Reactive with acids |
| Corrosivity | Non-corrosive in presence of glass |
Detecting free Iron : Spray the surface with a solution of potassium ferricyanide. If free iron is present, a blue color will appear. This test is extremely sensitive and often gives false positive results, that is, it gives an indication of iron being present when it really is not. The ferroxyl solution must be made fresh each day by addition with Nitric acid. The ferroxyl tests are described in ASTM A380.
Ferroxyl indicator is a solution containing potassium hexacyanoferrate(III) and phenolphthalein. It turns blue in the presence of Fe2+ ions, pink in the presence of hydroxide ions, it can be used to detect metal oxidation. It is often used to detect rusting in various situations.
It can be prepared by dissolving 10g sodium chloride and 1g potassium hexacyanoferrate(III) in distilled water, adding 10 cm3 phenolphthalein indicator, then making up to 500 cm3 with distilled water.