Sodium hexacyanoferrate(II)

From Crystal growing

   Sodium hexacyanoferrate(II)   
Names: sodium hexacyanoferrate(II)
sodium hexacyanoferroate
sodium cyanoferrate
sodium ferrocyanide
yellow prussiate of soda

Formula: Na4[Fe(CN)6] (anhydrous)
Na4[Fe(CN)6] · 10H2O (decahydrate)
SMILES: [C-]#N.[C-]#N.[C-]#N.[C-]#N.[C-]#N.[C-]#N.[Na+].[Na+].[Na+].[Na+].[Fe+2]
Molar mass: 303.913 g/mol (anhydrous)
484.062 g/mol (decahydrate)
Density: 1.458 g/cm3 (anhydrous)
1.329 g/cm3 (decahydrate)
Crystal system: monoclinic (decahydrate)
α=90°, γ=90°

Color: bright-yellow
Melting point: 650 °C923.15 K <br />1,202 °F <br />1,661.67 °R <br /> (anhydrous)
Refractive index: 1.531 (decahydrate)
Magnetic properties: diamagnetic
Stability: slightly erodes (decahydrate)
Hardness: relatively strong
Toxicity: non-toxic


Inorganic complex compound, salt of alkaline metal sodium and inorganic ferrocyanide acid. From water solutions crystallizes as decahydrate.


Reaction between potassium ferrocyanide, hydrochloric acid and sodium hydroxide

Chemical equation:

K4[Fe(CN)6] + 4HCl = H4[Fe(CN)6]↓ + 4KCl
H4[Fe(CN)6] + 4NaOH = Na4[Fe(CN)6] + 4H2O

For preparation of 100.00g of sodium hexacyanoferrate(II) decahydrate а 87.26g of potassium ferrocyanide trihydrate and 33.05g of sodium hydroxide or 81.43g of 37% hydrochloric acid is required.

Add to the flask with potassium ferrocyanide solution small parts of hydrochloric acid solution and stir. The large amount of poorly soluble precipitate will form. Settle it out and wash it from soluble impurities few times.Add to flask with hot concentrated solution of sodium hydroxide small amount of that precipitate with intense stirring. Heat it to 100°C for few minutes for reaction completion and then filter out. For purifying compound from hydroxide add large amount of cold ethanol, acetone or toluene to solution, salt will settle to the bottom in the form of fine crystals or powder. Filter precipitate and wash it with small amount of the same solvent, then filter the solution and use it for crystal growing.

Reaction between prussian blue and sodium hydroxide

Chemical equation:

Fe4[Fe(CN)6]3 + 12NaOH = 3Na4[Fe(CN)6] + 4Fe(OH)3

For preparation of 100.00g of sodium hexacyanoferrate(II) decahydrate а 33.05g of sodium hydroxide and 59.17g of prussian blue is required.

Add to flask with prussian blue small amount of water until it will become a thick slurry. Then add small parts of diluted hydroxide solution with intense stirring. Mixture will change color from dark-blue to dark-brown, become more homogeneous and could even boils because of exothermic. Heat it to 100°C for few minutes for reaction completion, filter out a precipitation of iron hydroxide.

Reaction between potassium ferrocyanide and sodium cation-exchange resin

Chemical equation:

K4[Fe(CN)6] + 4Na+ = Na4[Fe(CN)6] + 4K+

For preparation of 100.00g of sodium hexacyanoferrate(II) decahydrate а 73.95g of potassium ferrocyanide trihydrate is required.

Add warm potassium ferrocyanide solution to chemical column with sodium cation exchange resin and shake it.

Influence of temperature

Growing at higher temperature gives mostly polycrystalline.


Slowly reacts with diluted sulfuric acid with poisonous hydrocyanic acid emission, so be careful. Concentrated acid decomposes it to carbon monoxide, another ones gives participate of ferrocyanide acid.

Storage conditions

Store in its original form or under several layers of varnish at average humidity and room temperature. Do not store in matchboxes or cotton wool and do not heat.


Temperatureгр/100,00 гр water
0°C273.15 K <br />32 °F <br />491.67 °R <br />~11.4~17.3
10°C283.15 K <br />50 °F <br />509.67 °R <br />~14.7~24.6
15°C288.15 K <br />59 °F <br />518.67 °R <br />~16.3~28.2
20°C293.15 K <br />68 °F <br />527.67 °R <br />17.931.85
25°C298.15 K <br />77 °F <br />536.67 °R <br />20.725~38.8
30°C303.15 K <br />86 °F <br />545.67 °R <br />23.5~43.5
40°C313.15 K <br />104 °F <br />563.67 °R <br />30.2~58.6
50°C323.15 K <br />122 °F <br />581.67 °R <br />~36.4~74.6
60°C333.15 K <br />140 °F <br />599.67 °R <br />42.5~90.5
70°C343.15 K <br />158 °F <br />617.67 °R <br />~50.9~118
80°C353.15 K <br />176 °F <br />635.67 °R <br />59.2~145.3
90°C363.15 K <br />194 °F <br />653.67 °R <br />~61.1~151
100°C373.15 K <br />212 °F <br />671.67 °R <br />63156.5
Insoluble in ethanol, methanol, acetone, diethyl ether, toluene, aniline, pyridine, ethyl acetate and isopropanol.