Tripotassium-sodium hexacyanoferrate(II)

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Crystal compoundsSaltsCyanidesTripotassium-sodium hexacyanoferrate(II)


  Tripotassium-sodium hexacyanoferrate(II)   
Names: tripotassium-sodium hexacyanoferrate(II)
tripotassium-sodium hexacyanoferroate
tripotassium-sodium cyanoferrate
tripotassium-sodium ferrocyanide
yellow prussiate of potash-soda
Formula: K3Na[Fe(CN)6] (anhydrous)
K3Na[Fe(CN)6] · 3H2O (trihydrate)
Molar mass: 352.237 g/mol (anhydrous)
406.282 g/mol (trihydrate)
Crystal system: rhombohedral (trihydrate)
Shapes:
https://media.crystalls.info/w/uploads/media/Prolongated_oblique_hexagonal_prism.json
https://media.crystalls.info/w/uploads/media/Oblique_rhombic_prism.json

Color: yellow
red because of partial oxidation
Magnetic properties: diamagnetic
Stability: erodes (trihydrate)
Hardness: fragile
Toxicity: non-toxic

Description

Inorganic complex compound, salt of alkaline metals potassium and sodium and inorganic ferrocyanide acid. From water solutions crystallizes as trihydrate.

Precursors

Reaction between potassium and sodium hexacyanoferrates

Chemical equation:

3K4[Fe(CN)6] + Na4[Fe(CN)6] = 4K3Na[Fe(CN)6]↑

For preparation of 100.00g of tripotassium-sodium hexacyanoferrate(II) trihydrate а 77.97g of potassium hexacyanoferrate(II) trihydrate and 29.79g of sodium hexacyanoferrate(II) decahydrate is required.
Dissolve compounds in hot water apart and then mix solutions into one container with intense stirring. Cooling or evaporation of a solution will cause double salt crystallyzation. Filter precipitate and wash it wish small amount of ethanol, acetone or toluene, then filter the solution and use it for crystal growing.

Reaction between potassium ferricyanide, sodium hydroxide and hydrogen peroxide

Chemical equation:

2K3[Fe(CN)6] + H2O2 + 2NaOH = 2K3Na[Fe(CN)6] + 2H2O + O2

For preparation of 100.00g of tripotassium-sodium hexacyanoferrate(II) trihydrate а 9.84g of sodium hydroxide, 13.95g of 30% peroxide and 81.04g of potassium ferricyanide is required.
Add to the flask with potassium ferricyanide solution hydrogen peroxide and then add small parts of sodium hydroxide with stirring until oxide emission will stop. 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 potassium ferrocyanide, hydrochloric acid and potassium and sodium hydroxide

Chemical equation:

K4[Fe(CN)6] + 4HCl = H4[Fe(CN)6]↓ + 4KCl
H4[Fe(CN)6] + 3KOH + NaOH = K3Na[Fe(CN)6] + 4H2O

For preparation of 100.00g of tripotassium-sodium hexacyanoferrate(II) trihydrate а 103.96g of potassium ferrocyanide trihydrate, 9.84g of sodium hydroxide and 41.43g of potassium hydroxide or 97.02g 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 and potassium hydroxides small amount of that precipitate with intense stirring. Heat it to 100°C for few minutes for reaction completion and then filter out.

Reaction between prussian blue and potassium and sodium hydroxide

Chemical equation:

Fe4[Fe(CN)6]3 + 9KOH + 3NaOH = 3K3Na[Fe(CN)6] + 4Fe(OH)3

For preparation of 100.00g of tripotassium-sodium hexacyanoferrate(II) trihydrate а 9.84g of sodium hydroxide, 41.43g of potassium hydroxide and 70.50g 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.

Influence of temperature

Growing at higher temperature gives mostly polycrystalline.

Notes

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

For crystal storing use hermetic vessel with small amount of saturated solution at the bottom or place wadding moistened with such solution. You can use such alternatives as vessel with vaseline or vegetable oil, organic non-hygroscopic solvent (kerosene, benzine or paraffin). Also you can use acrylate polymer or another kinds of solidifying plastic.

Solubility

Temperatureгр/100,00 гр water
(anhydrous)(trihydrate)
0°C
273.15 K
32 °F
491.67 °R
~13.6
13.6 g/100g
11.972 %
~15.8
15.8 g/100g
13.644 %
10°C
283.15 K
50 °F
509.67 °R
~19.5
19.5 g/100g
16.318 %
~23.1
23.1 g/100g
18.765 %
15°C
288.15 K
59 °F
518.67 °R
~22.9
22.9 g/100g
18.633 %
~26.9
26.9 g/100g
21.198 %
20°C
293.15 K
68 °F
527.67 °R
~26.2
26.2 g/100g
20.761 %
~30.7
30.7 g/100g
23.489 %
25°C
298.15 K
77 °F
536.67 °R
~29.3
29.3 g/100g
22.66 %
~35.0
35 g/100g
25.926 %
30°C
303.15 K
86 °F
545.67 °R
~32.4
32.4 g/100g
24.471 %
~39.3
39.3 g/100g
28.212 %
40°C
313.15 K
104 °F
563.67 °R
~38.9
38.9 g/100g
28.006 %
~47.2
47.2 g/100g
32.065 %
50°C
323.15 K
122 °F
581.67 °R
~46.0
46 g/100g
31.507 %
~57.1
57.1 g/100g
36.346 %
60°C
333.15 K
140 °F
599.67 °R
~52.3
52.3 g/100g
34.34 %
~63.5
63.5 g/100g
38.838 %
70°C
343.15 K
158 °F
617.67 °R
~58.7
58.7 g/100g
36.988 %
~69.9
69.9 g/100g
41.142 %
80°C
353.15 K
176 °F
635.67 °R
~65.0
65 g/100g
39.394 %
~76.3
76.3 g/100g
43.279 %
90°C
363.15 K
194 °F
653.67 °R
~68.2
68.2 g/100g
40.547 %
~80.4
80.4 g/100g
44.568 %
100°C
373.15 K
212 °F
671.67 °R
~71.4
71.4 g/100g
41.657 %
~84.5
84.5 g/100g
45.799 %
Insoluble in ethanol, methanol, acetone, diethyl ether, toluene, aniline, pyridine, ethyl acetate and isopropanol.

Gallery


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