Iron(II) acetate

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  Iron(II) acetate   
Names: iron(II) acetate
iron triacetate
ferrous acetate

Formula: Fe(CH3COO)2 (anhydrous)
Fe(CH3COO)2 · 4H2O (tetrahydrate)
SMILES: CC(=O)[O-].CC(=O)[O-].[Fe+2]
Molar mass: 173.933 g/mol (anhydrous)
245.992 g/mol (tetrahydrate)
Density: 1.734 g/cm3 (anhydrous)
Crystal system: orthorhombic (tetrahydrate)
a=18.1715 Å
18.1715 Å
1.8172 nm
, b=22.1453 Å
22.1453 Å
2.2145 nm
, c=8.2781 Å
8.2781 Å
0.8278 nm
α=90°
90°  
, β=90°
90°  
, γ=90°
90°  

Shapes:
https://media.crystalls.info/w/uploads/media/Prolongated_hexagonal_flat_prism.json
https://media.crystalls.info/w/uploads/media/Trapezoidal_flat_prism.json

Color: colorless
redden on the air
Decomposition point: 190 °C
463.15 K
374 °F
833.67 °R
(anhydrous)
Magnetic properties: paramagnetic
Stability: very unstable. erodes during few seconds (tetrahydrate)
Hardness: very fragile
Toxicity: slightly toxic

Description

Organic compound, salt of bivalent transition metal iron and organic acetic acid. From water solutions crystallizes as tetrahydrate.

Precursors

Reaction between iron(II) hydroxocarbonate, hydroxide or oxide and acetic acid

Chemical equation:

4CH3COOH + Fe2(CO3)(OH)2 = 2Fe(CH3COO)2 + 3H2O + CO2
2CH3COOH + Fe(OH)2 = Fe(CH3COO)2 + 2H2O
2CH3COOH + FeO = Fe(CH3COO)2 + H2O

For preparation of 100.00g of iron(II) acetate tetrahydrate а 41.81g of hydroxycarbonate or 36.53g of hydroxide or 29.21g of oxide and 69.75g of 70% of acetic 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.

Dissolving an iron powder in acetic acid

Chemical equation:

2CH3COOH + Fe = Fe(CH3COO)2 + H2

For preparation of 100.00g of iron(II) acetate tetrahydrate а 22.70g of pure iron and 69.75g of 70% of acetic acid is required.
Add warm acid solution to the flask, then add iron pieces, shavings or powder and stir it until gas emission will stop.

Reaction between iron(II) chloride, sulfate or nitrate and excess of concentrated acetic acid

Chemical equation:

2CH3COOH + FeCl2 = Fe(CH3COO)2↓ + 2HCl
2CH3COOH + FeSO4 = Fe(CH3COO)2↓ + H2SO4
2CH3COOH + Fe(NO3)2 = Fe(CH3COO)2↓ + 2HNO3

For preparation of 100.00g of iron(II) acetate tetrahydrate а 80.82g of iron(II) chloride tetrahydrate or 113.02g of iron(II) sulfate heptahydrate or 117.05g of iron(II) nitrate hexahydrate and 48.82g of glacial acid acetic is required.
Add to the flask with hot iron compounds solution a acid solution with heating and stirring. Cooling this mixture will cause forming a large amount of crystalline precipitation. Filter precipitate and wash it wish small amount of glacial acetic acid, then filter the solution and use it for crystal growing.

Reaction between iron(II) nitrate and sodium acetate

Chemical equation:

2NaCH3COO + Fe(NO3)2 = Fe(CH3COO)2↓ + 2NaNO3

For preparation of 100.00g of iron(II) acetate tetrahydrate а 117.05g of iron(II) nitrate hexahydrate and 110.64g of sodium acetate trihydrate is required.
Add to the flask with hot iron(II) nitrate solution a sodium acetate solution with heating and stirring. Cooling this mixture will cause forming a large amount of crystalline precipitation. Filter precipitate and wash it wish small amount of cold water, then filter the solution and use it for crystal growing.

Reaction between iron(II) sulfate and calcium or lead(II) acetate

You can use iron(II) chloride instead of sulfate if you use lead salt..
Chemical equation:

Ca(CH3COO)2 + FeSO4 = Fe(CH3COO)2 + CaSO4
Pb(CH3COO)2 + FeSO4 = Fe(CH3COO)2 + PbSO4
Pb(CH3COO)2 + FeCl2 = Fe(CH3COO)2 + PbCl2

For preparation of 100.00g of iron(II) acetate tetrahydrate а 80.82g of iron(II) chloride tetrahydrate or 113.02g of iron(II) sulfate heptahydrate and 71.62g of calcium acetate monohydrate or 154.21g of lead(II) acetate trihydrate is required.
Add to the flask with calcium or lead acetate solution small parts of iron salt solution and stir. The large amount of poorly soluble precipitate will form. Settle it out and discard, then filter the solution carefully.

Influence of temperature

It`s recommended to grow crystals at -7...-10 °C. For better results you should grow them with slow solution cooling method.

Influence of pH level

Water solutions are hydrolytically unstable and rapidly oxidizes by atmospheric oxygen to bright-red iron(III) acetates and hydroxyacetates.
So it`s recommended to add excess of acetic and sulfuric acid for stopping the hydrolysis.

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

Highly soluble in water. Soluble in ethanol.

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