Iron(II)-ammonium sulfate

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Crystal compoundsSaltsSulfatesIron(II)-ammonium sulfate


  Iron(II)-ammonium sulfate   
Names: diammonium-iron sulfate
ferrous ammonium sulfate
ammonium iron sulfate
Mohr's salt
iron Tutton's salt
ferrous Tutton's salt
ammonium iron schoenite
NISH
NFSH

Formula: (NH4)2Fe(SO4)2 (anhydrous)
(NH4)2Fe(SO4)2 · 6H2O (hexahydrate)
SMILES: [O-]S(=O)(=O)[O-].[O-]S(=O)(=O)[O-].[Fe+2].[NH4+].[NH4+]
Molar mass: 284.045 g/mol (anhydrous)
392.134 g/mol (hexahydrate)
Density: 1.86 g/cm3 (hexahydrate)
Crystal system: monoclinic (hexahydrate)
a=9.32 Å
9.3200 Å
0.9320 nm
, b=12.65 Å
12.6500 Å
1.2650 nm
, c=6.24 Å
6.2400 Å
0.6240 nm
α=90°
90°  
, β=106.8°
106°47′60.0″  
, γ=90°
90°  

Shapes:
https://media.crystalls.info/w/uploads/media/Deformed_tetragonal_bipyramid.json
https://media.crystalls.info/w/uploads/media/Beveled_rhombic_prism.json
https://media.crystalls.info/w/uploads/media/Truncated_deformed_hexagonal_prism.json
https://media.crystalls.info/w/uploads/media/Truncated_trigonal_prism.json

Color: light-green
pale-green
Decomposition point: 105 °C
378.15 K
221 °F
680.67 °R
(hexahydrate)
Stability: stable (hexahydrate)
hygroscopic (anhydrous)
Hardness: relatively strong
Toxicity: non-toxic
LD50=3250mg/kg

Description

Inorganic compound, double salt of transitional metal iron, ammonium ion and inorganic sulfuric acid. From water solutions crystallizes as hexahydrate.

Minerals

Occurs in nature as mohrite mineral.

Precursors

Reaction between iron(II) and ammonium sulfates

Chemical equation:

(NH4)2SO4 + FeSO4 = (NH4)2Fe(SO4)2

For preparation of 100.00g of iron(II)-ammonium sulfate hexahydrate а 70.90g of iron(II) sulfate heptahydrate and 33.70g of ammonium sulfate 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 or acetone, then filter the solution and use it for crystal growing.

Reaction between iron(II) chloride or nitrate and ammonium sulfate

Chemical equation:

2(NH4)2SO4 + FeCl2 = (NH4)2Fe(SO4)2↓ + 2NH4Cl
2(NH4)2SO4 + Fe(NO3)2 = (NH4)2Fe(SO4)2↓ + 2NH4NO3

For preparation of 100.00g of iron(II)-ammonium sulfate hexahydrate а 50.70g of ammonium chloride tetrahydrate or 73.43g of iron(II) nitrate hexahydrate and 67.39g of sulfate is required.
Add to the flask with saturated iron compound solution a ammonium sulfate solution with stirring. Freezing this mixture will cause forming a large amount of crystalline precipitationof Mohr's salt. For purifying compound from unreacted compounds add large amount of cold ethanol or acetone 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 iron(II) sulfate and ammonium nitrate or chloride

Chemical equation:

2NH4Cl + 2FeSO4 = (NH4)2Fe(SO4)2↓ + 2FeCl2
2NH4NO3 + 2FeSO4 = (NH4)2Fe(SO4)2↓ + 2Fe(NO3)2

For preparation of 100.00g of iron(II)-ammonium sulfate hexahydrate а 27.28g of ammonium chloride or 40.82g of nitrate and 141.79g of iron(II) sulfate heptahydrate is required.
Add to the flask with saturated iron(II) sulfate solution a ammonium salt solution with stirring. Freezing this mixture will cause forming a large amount of crystalline precipitationof Mohr's salt. For purifying compound from unreacted compounds add large amount of cold ethanol or acetone 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 iron ammonium alum, pure iron and sulfuric acid

Chemical equation:

2NH4Fe(SO4)2 + Fe + 3H2SO4 = (NH4)2Fe(SO4)2↓ + Fe2(SO4)3 + 3H2

For preparation of 100.00g of iron(II)-ammonium sulfate hexahydrate а 135.67g of iron ammonium alum, 14.24g of iron and 202.79g of 37% sulfuric acid is required.
Add diluted acid to the flask, then add small parts of iron with pure metal iron compound with stirring until it will totally dissolve . For purifying compound from unreacted compounds add large amount of cold ethanol or acetone 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.

Influence of impurities

Excess of iron(II) sulfate influenses on crystal shape and leads to growth of polycrystalline.
Excess of ammonium sulfate influenses on crystal shape and leads to transparency deterioration.
Addition of glycerol leads to flattening of crystal shape and positively influences on transparency.

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.

Solubility

Temperatureгр/100,00 гр water
0°C
273.15 K
32 °F
491.67 °R
12.5
12.5 g/100g
11.111 %
10°C
283.15 K
50 °F
509.67 °R
17.2
17.2 g/100g
14.676 %
15°C
288.15 K
59 °F
518.67 °R
~19.4
19.4 g/100g
16.248 %
20°C
293.15 K
68 °F
527.67 °R
21.6
21.6 g/100g
17.763 %
25°C
298.15 K
77 °F
536.67 °R
~24.5
24.5 g/100g
19.679 %
30°C
303.15 K
86 °F
545.67 °R
~27.3
27.3 g/100g
21.445 %
40°C
313.15 K
104 °F
563.67 °R
33
33 g/100g
24.812 %
50°C
323.15 K
122 °F
581.67 °R
40
40 g/100g
28.571 %
60°C
333.15 K
140 °F
599.67 °R
~46.0
46 g/100g
31.507 %
70°C
343.15 K
158 °F
617.67 °R
52
52 g/100g
34.211 %
80°C
353.15 K
176 °F
635.67 °R
~62.5
62.5 g/100g
38.462 %
90°C
363.15 K
194 °F
653.67 °R
73
73 g/100g
42.197 %
Insoluble in ethanol and acetone.

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