What is the molar mass ferrous ammonium sulfate hexahydrate

The molar mass ferrous ammonium sulfate hexahydrate can be shown in different forms, which can be abbreviated as FeNH₄SO₄·6H₂O, has a molar mass of 390 grams per mole or 192.06 g/mol and a density of 1.516 g/cm or 1.518 g/cm, and a specific gravity of 1.615 g/cm or 1.618 g/cm at 25℃ or 77.4℉. The water-soluble molar mass can form precipitates of anhydrous iron(II) sulfide with sulfur dioxide at the room temperature, and it contains the formula Fe(NH₄)SO₄·6H₂O that has a molecular mass of 393 grams per mole or 191.23 g/mol and a density of 1.515g/cm, 6H₂O and 3H₂O.1.

Properties of ferrous ammonium sulfate hexahydrate

1.Light green to blue crystals or crystal

The Light green to blue crystals or crystal can be highlighted by the dark blue background and precipitate with oxidation of ferrous ion during light radiation and moisture activity, apparently it is not soluble in water. The crystals may contain other colors like yellow, red and black (in which case the color of the crystal is due to impurities in the crystal) but it does not affect its properties. Ferrous ammonium sulfate hexahydrate that contains 2-3% of ferric ion will have a similar color as ferrous ammonium sulfate hexahydrate although their specific gravities are different. The crystals can be obtained based on precipitation in 7% ammonia solution or by adding sulfur dioxide gas into a water solution mixed with ammonia solution.

2.Solubility in water

In the area of 0-4℃ or 32-39℉, the solubility of ferrous ammonium sulfate hexahydrate is only 0.00025g/cm³ or 13.13ppm at 20g/L, while in the area of 4-27℃ or 39-81.6℉, the solubility of ferrous ammonium sulfate hexahydrate is 0.00038g/cm³ or 19ppm at 20g/L; In the area of 28-38℃ or 81.6-100℉, the solubility of ferrous ammonium sulfate hexahydrate is 0.00041g/cm³ or 21ppm at 20g/L and the maximum solubility will be reached at an area of 42-46℃ or 107.6-114.8℉, which is 0.00058g/cm³ or 30ppm; The solubility of ferrous ammonium sulfate hexahydrate in water solution decreases with increasing temperature and vanishes at 100℃ or 212℉;

3.Concentration of ferrous ion

The concentration of ferrous ion increases with lowering temperature and changes from 0.0003-0.0015g/cm³ or 0.00055-0.007g/cm³ at room temperature or 20℃ to 0.0045-0.015g/cm³ or 0.009-0.014g/cm³ at 50℃ or 122℉, and vanishes at 100℃ or 212℉; The ferrous ion concentration in ferrous ammonium sulfate hexahydrate is 0.0020-0.0045g/cm³ or 0.04-0.09g/ml at 20g/L and the concentration of ferrous ion in the crystal is about 2 times that of the solution;

4.Concentration of sulfate ion

The concentration of sulfate ion increases with decreasing temperature and changes from 0.01-0.03g/cm³ or 0.07-0.2g/cm³ at room temperature or 20℃ to 0.04-0.085g/cm³ or 0.2-1g/cm³ at 50℃ or 122℉, which is the same as that of lead(II) sulfate; The solubility of ferrous ammonium sulfate hexahydrate in water solution decreases with increasing temperature and the maximum solubility will be reached at an area of 44-46℃ or 111.2-114.8℉, which is 0.042g/cm³ or 1g/cm³.

5.Mass of metal ions

The mass of metal ions(Fe and Fe) can be obtained from formula Fe+6SO₄=FeSO₄+6H₂O, the molar masses of iron and sulfate are 65.865g/mol and 136.033 g/mol respectively, the molar mass fertinum sulfate hexahydrate is thus 65.865 x 2 + 136.033 = 392.4967 g/mol, the mass of iron(II) ion is calculated as 65.865/392.4967=0.164g or 164mg/mol;

Uses of ferrous ammonium sulfate hexahydrate

1.Food and beverages

Ferrous ammonium sulfate hexahydrate is used in food and beverages, it is often used as a flavor enhancer in the production of ice cream, cakes and other foods. Ferrous ammonium sulfate hexahydrate is mainly used as an additive for the prevention of yellowing of frozen food. The color of products containing ferrous ammonium sulfate hexahydrate will be a blueish or greenish color instead tan due to the addition into the product ingredient;

2.Pharmaceutical and industrial

The molar mass ferrous ammonium sulfate hexahydrate can be used as a colloidal metal ion in pharmaceuticals, such as electroplating and other industries, it is also used for producing ferroalloys, fertilizers and other chemicals. Ferrous ammonium sulfate hexahydrate is often used as a catalyst for methanol oxidation reaction by the addition of several g/l at the temperature of 50℃. The reaction is exothermic and occurs with the production of hydrogen gas through complexation with Fe(II);

3.Chemical reagent

Ferrous ammonium sulfate hexahydrate is a chemical reagent for the detection of iron(III) and tin(II), which is chosen because of its good solubility in water, moderate oxidation and low toxicity. The detection procedures are R-123 and R-126, in which two chemicals are respectively added into two tubes containing ferrous ammonium sulfate hexahydrate, if the color changes from blue to green then it indicates that there is Fe(III) ion in one tube and Sn(II) ion in another tube.

In conclusion, the molar mass ferrous ammonium sulfate hexahydrate is used as a food additive for food preservation, pharmaceuticals and colorants; It can be used as a reagent for the detection of iron(III) and tin(II). Ferrous ammonium sulfate hexahydrate is easy to be precipitated by sulfur dioxide, chlorite and other chemicals in solution.