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Iron(II) sulfate

From Crystal growing


   Iron(II) sulfate   
Names: ferrous sulfate
iron vitriol
green vitriol
Formula: FeSO4 (anhydrous)
FeSO4 · 4H2O (tetrahydrate)
FeSO4 · 7H2O (heptahydrate)
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, b=6.8013 Å, c=4.7868 Åα=90°, β=90°, γ=90°
monoclinic (monohydrate, szomolnokite)
a=7.62 Å, b=7.47 Å, c=7.12 Åα=90°, β=115.85°, γ=90°
monoclinic (tetrahydrate, rozenite)
a=5.979 Å, b=13.648 Å, c=7.977 Åα=90°, β=90.26°, γ=90°
monoclinic (heptahydrate, melanterite)
a=14.077 Å, b=6.509 Å, c=11.054 Åα=90°, β=105.6°, γ=90°
Shapes:
https://en.crystalls.info/w/uploads/media/b/bc/Rhombic_prism.json
https://en.crystalls.info/w/uploads/media/3/37/Octahedron.json
https://en.crystalls.info/w/uploads/media/f/fd/Beveled_truncated_rhombic_prism.json
https://en.crystalls.info/w/uploads/media/f/fa/Truncated_rhombic_pyramid.json

Template:Rhombohedron

Color: lime green
green
white
Decomposition point: 680 °C953.15 K <br />1,256 °F <br />1,715.67 °R <br /> (anhydrous)
Refractive index: 1.591 (anhydrous)
1.526 (tetrahydrate)
1.471 (heptahydrate)
Magnetic properties: paramagnetic
χ=1.24 · 10-2cm³/mol
Stability: highly erodes (heptahydrate)
stable (tetrahydrate)
hygroscopic (anhydrous)
Hardness: relatively strong
(2 on Moh's scale)
Toxicity: moderately toxic
LD50=237mg/kg

Description

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

Minerals

Occurs in nature as melanterite, rozenite and szomolnokite minerals.

Where to buy

Can be bought in fertilizers store (as "iron vitriol").

Precursors

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 of 100.00g of iron(II) sulfate heptahydrate а 32.32g of hydroxide or 25.84g of oxide and 95.35g of 37% 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 of 100.00g of iron(II) sulfate heptahydrate а 20.09g of iron and 95.35g of 37% 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 of 100.00g of iron(II) sulfate heptahydrate а 20.09g of iron and 89.81g of copper(II) sulfate pentahydrate 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 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.

Solubility

Temperatureгр/100,00 гр waterгр/100,00 гр glycerolгр/100,00 гр ethylene glycol
(anhydrous)(heptahydrate)(heptahydrate)(heptahydrate)
0°C273.15 K <br />32 °F <br />491.67 °R <br />15.607
10°C283.15 K <br />50 °F <br />509.67 °R <br />20.482
15°C288.15 K <br />59 °F <br />518.67 °R <br />25
20°C293.15 K <br />68 °F <br />527.67 °R <br />26.26328.86.4
25°C298.15 K <br />77 °F <br />536.67 °R <br />29.534
30°C303.15 K <br />86 °F <br />545.67 °R <br />32.979
40°C313.15 K <br />104 °F <br />563.67 °R <br />40.44940
50°C323.15 K <br />122 °F <br />581.67 °R <br />48.8148.6
60°C333.15 K <br />140 °F <br />599.67 °R <br />55.03960
70°C343.15 K <br />158 °F <br />617.67 °R <br />50.60273.3
80°C353.15 K <br />176 °F <br />635.67 °R <br />43.678
90°C363.15 K <br />194 °F <br />653.67 °R <br />37.17479.9
100°C373.15 K <br />212 °F <br />671.67 °R <br />31.579
Insoluble in ethanol.


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