Iron(II) sulfate

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  Iron(II) sulfate   
Names: ferrous sulfate
iron vitriol

Formula: FeSO4
FeSO4 · 4H2O
FeSO4 · 7H2O
SMILES: [O-]S(=O)(=O)[O-].[Fe+2]
Molar mass: 151.906 g/mol (anhydrous)
223.966 g/mol (tetrahydrate)
278.010 g/mol (heptahydrate)
Density: 3.56 g/cm3 (anhydrous)
3 g/cm3 (monohydrate)
2.15 g/cm3 (tetrahydrate)
1.898 g/cm3 (heptahydrate)
Crystal system: orthorhombic (anhydrous)
a=8.7042 Å
8.7042 Å
0.8704 nm
, b=6.8013 Å
6.8013 Å
0.6801 nm
, c=4.7868 Å
4.7868 Å
0.4787 nm
α=90°
90°  
, β=90°
90°  
, γ=90°
90°  

monoclinic (monohydrate)
a=7.62 Å
7.6200 Å
0.7620 nm
, b=7.47 Å
7.4700 Å
0.7470 nm
, c=7.12 Å
7.1200 Å
0.7120 nm
α=90°
90°  
, β=115.85°
115°50′60.0″  
, γ=90°
90°  

monoclinic (tetrahydrate)
a=5.979 Å
5.9790 Å
0.5979 nm
, b=13.648 Å
13.6480 Å
1.3648 nm
, c=7.977 Å
7.9770 Å
0.7977 nm
α=90°
90°  
, β=90.26°
90°15′36.0″  
, γ=90°
90°  

monoclinic (heptahydrate)
a=14.077 Å
14.0770 Å
1.4077 nm
, b=6.509 Å
6.5090 Å
0.6509 nm
, c=11.054 Å
11.0540 Å
1.1054 nm
α=90°
90°  
, β=105.6°
105°35′60.0″  
, γ=90°
90°  

Forms:
https://media.crystalls.info/w/uploads/media/Rhombic_prism.json
https://media.crystalls.info/w/uploads/media/Octahedron.json
https://media.crystalls.info/w/uploads/media/Beveled_truncated_rhombic_prism.json
https://media.crystalls.info/w/uploads/media/Truncated_rhombic_pyramid.json

Template:Rhombohedron

Color: lime green

green white

Decomposition point: 680°C
953.15 K
1,256 °F
1,715.67 °R
(anhydrous)
300°C
573.15 K
572 °F
1,031.67 °R
(monohydrate)
100°C
373.15 K
212 °F
671.67 °R
(tetrahydrate)
62°C
335.15 K
143.6 °F
603.27 °R
(heptahydrate)
Refractive index: 1.591 (anhydrous)
1.526 (tetrahydrate)
1.471 (heptahydrate)
Electrical properties: dielectric
Magnetic properties: paramagnetic
χ=1.24 · 10-2 cm³/mol
Stability: highly erodes (heptahydrate)
stable (tetrahydrate)
hygroscopic (anhydrous)
Hardness: fragile
Toxicity: slightly toxic

==Description == Inorganic compound, salt of bivalent transitional metal iron and inorganic sulfuric acid. From water solutions crystallizes as tetrahydrate and heptahydrate.

Minerals

Occurs in nature as melanterite, rozenite and szomolnokite minerals.

Where to buy

In fertilizers store (as "iron vitriol").

Synthesis

Reaction between iron(II) hydroxycarbonate, hydroxide or oxide and sulfuric acid

Chemical equation:

2H2SO4 + Fe2CO3(OH)2 = 2FeSO4 + 3H2O + CO2
H2SO4 + Fe(OH)2 = FeSO4 + 2H2O
H2SO4 + FeO = FeSO4 + H2O

For preparation 100g of iron(II) sulfate heptahydrate a 37.00g of iron(II) hydroxycarbonate, 32.32g of hydroxide or 25.84g of oxide and 103.76g of 34% sulfuric acid is required.
Add acid to the flask, then add small parts of iron compound with stirring until it will totally dissolve or, if you use carbonate, until carbon dioxide emission will stop. After reaction will stop, filter the solution and use it for crystal growing.

====Reaction between metal iron and sulfuric acid==== Chemical equation:

H2SO4 + Fe = FeSO4 + H2

For preparation 100g of iron(II) sulfate heptahydrate a 20.09g of iron and 103.76g of 34% sulfuric acid is required.
Add diluted acid solution to the flask, then add iron pieces, shavings or powder and stir it until gas emission will stop.

====Reaction between metal iron and copper(II) sulfate==== Chemical equation:

CuSO4 + Fe = FeSO4 + Cu↓

For preparation 100g of iron(II) sulfate heptahydrate a 20.09g of iron and 89.81g of copper(II) sulfate pentahydrate or 114.82g of anhydrous copper(II) sulfate is required.
Add copper(II) sulfate solution to the flask, then add iron pieces, shavings or powder and leave for a few days. After solution color changing will stop, less active metal will completely displace into the precipitate. Then filter the solution.

==Influence of temperature== While solution tempetature is above 56.8°C, mostly tetrahydrate crystal forms. However, the increase in temperature also leads to a faster hydrolysis of the substance, with simultaneous oxidation to Iron(III) sulfate.

Influence of impurities

Nickel(II) sulfate impurities lead to formation of polycrystals with a darker color.

Influence of pH level

Addition of sulfuric acid positively affects crystals transparency and oxidation stability. It is highly recommended to use.
The addition of more than 55% by weight (dissolution of heparahydrate directly in the battery electrolyte with further evaporation of excess water) leads to the growth of tetrahydrate crystals, much more resistant to weathering.

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.

THere is no any special conditions to store crystals of tetrahydrate

Solubility

Temperatureg/100g of waterg/100g of glycerolg/100g of ethylene glycol
(anhydrous)(heptahydrate)(heptahydrate)(heptahydrate)
0°C
273.15 K
32 °F
491.67 °R
15.607
15.607 g/100g
13.5 %
10°C
283.15 K
50 °F
509.67 °R
20.482
20.482 g/100g
17 %
15°C
288.15 K
59 °F
518.67 °R
~23.4
23.4 g/100g
18.963 %
25
25 g/100g
20 %
20°C
293.15 K
68 °F
527.67 °R
26.263
26.263 g/100g
20.8 %
28.8
28.8 g/100g
22.36 %
6.4
6.4 g/100g
6.015 %
25°C
298.15 K
77 °F
536.67 °R
29.534
29.534 g/100g
22.8 %
~31.6
31.6 g/100g
24.012 %
30°C
303.15 K
86 °F
545.67 °R
32.979
32.979 g/100g
24.8 %
~34.4
34.4 g/100g
25.595 %
40°C
313.15 K
104 °F
563.67 °R
40.449
40.449 g/100g
28.8 %
40
40 g/100g
28.571 %
50°C
323.15 K
122 °F
581.67 °R
48.810
48.81 g/100g
32.8 %
48.6
48.6 g/100g
32.705 %
60°C
333.15 K
140 °F
599.67 °R
55.039
55.039 g/100g
35.5 %
60
60 g/100g
37.5 %
70°C
343.15 K
158 °F
617.67 °R
50.602
50.602 g/100g
33.6 %
73.3
73.3 g/100g
42.297 %
80°C
353.15 K
176 °F
635.67 °R
43.678
43.678 g/100g
30.4 %
~76.6
76.6 g/100g
43.375 %
90°C
363.15 K
194 °F
653.67 °R
37.174
37.174 g/100g
27.1 %
79.9
79.9 g/100g
44.414 %
100°C
373.15 K
212 °F
671.67 °R
31.579
31.579 g/100g
24 %
Insoluble in ethanol.

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