Ammonium Sulfate Chemical Structure, Properties and Uses

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Jonah Lester
Ammonium Sulfate Chemical Structure, Properties and Uses

The ammonium sulphate It is a ternary ammoniacal inorganic salt of sulfuric acid. Its chemical formula is (NH4)twoSW4. Therefore, the stoichiometric proportions say that for each sulfate anion there are two ammonium cations interacting with it. This allows the neutrality of the salt ((+1) ∙ 2 + (-2)).

Its nomenclature is due to the fact that it is a salt derived from HtwoSW4, changing the suffix "uric" by "ato". Thus, the two initial protons are replaced by NH4+, product of reaction with ammonia (NH3). So, the chemical equation for its synthesis is: 2 NH3 + HtwoSW4 => (NH4)twoSW4

Ammonium sulfate is a nitrogen and sulfur buffer, both essential in soil chemistry and fertilizers..

Article index

  • 1 Chemical structure
  • 2 Physical and chemical properties
    • 2.1 Molecular weight
    • 2.2 Physical appearance
    • 2.3 Odor
    • 2.4 Melting point
    • 2.5 Solubility
    • 2.6 Density
    • 2.7 Vapor pressure
    • 2.8 Flash point
    • 2.9 pH
    • 2.10 Stability
    • 2.11 Decomposition
    • 2.12 Corrosion
  • 3 Uses
    • 3.1 In agriculture
    • 3.2 As an analytical reagent
    • 3.3 In the precipitation and isolation of proteins
    • 3.4 In industry
    • 3.5 Other uses
  • 4 References

Chemical structure

The image above illustrates the molecular geometries of NH ions.4+ And so4two-. The red spheres correspond to the oxygen atoms, the white spheres to the hydrogen atoms, the blue to the nitrogen atom and the yellow to the sulfur atom.

Both ions can be considered as two tetrahedra, thus having three units that interact to form an orthorhombic crystal arrangement. The sulfate anion is SO4two- and is capable of donating or accepting four hydrogen bonds, just like the NH cation4+.

Physical and chemical properties

Molecular weight

132.134 g / mol.

Physical appearance

Solid white. White or brown orthorhombic crystals, depending on impurity levels.

Odor

Toilet.

Melting point

280 ° C. This melting point, low compared to other ionic compounds, is due to the fact that it is a salt with monovalent cations (+1) and with dissimilar ions in their sizes, causing the solid to have a low crystalline lattice energy..

Solubility

76.4 g / 100 g of water at 25 ° C. This affinity for water is due to the great capacity of its molecules to solvate ammonium ions. On the other hand, it is insoluble in acetone and alcohol; that is, in solvents less polar than water.

Density

1.77 g / cm3 at 25 ºC.

Vapor pressure

1,871 kPa at 20 ºC.

Flash point

26 ºC.

pH

5.0-6.0 (25 ° C. 1M solution). The slightly acidic pH is due to the hydrolysis of NH4+ in water, producing H3OR+ at low concentrations.

Stability

Stable in suitable environmental conditions. In contact with strong oxidants it can ignite.

Decomposition

It begins to decompose at 150 ° C, releasing toxic fumes of sulfur oxide, nitrogen oxide and ammonium.

Corrosion

Does not attack iron or aluminum.

Applications

In the agriculture

- Ammonium sulfate is used as a fertilizer in alkaline soils. The ammonium salt has in its composition 21% nitrogen and 24% sulfur. However, there are compounds that provide a greater amount of nitrogen than ammonium sulfate; the advantage of the latter is its high concentration of sulfur.

- Sulfur is essential in protein synthesis, since several amino acids - such as cystine, methionine and cysteine ​​- have sulfur. For these reasons, ammonium sulfate continues to be one of the most important fertilizers.

- It is used in the crops of wheat, corn, rice, cotton, potatoes, hemp and fruit trees.

- It lowers the pH of alkaline soils due to its contribution to the nitrification process carried out by microbes. Ammonium (NH4+) to produce nitrate (NO3-) and release H+: 2NH4+ + 4thtwo => 2NO3- + 2HtwoO + 4H+. Increasing the hydrogen concentration lowers the pH of alkaline soils and allows more use.

- In addition to its use as a fertilizer, ammonium sulfate acts as an adjunct to soluble insecticides, herbicides and fungicides, which are sprayed on crops..

- Sulfate is capable of sequestering ions present in the soil and in irrigation water that are necessary for the life of certain pathogens. Among the ions that ammonium sulfate captures are Catwo+, the Mgtwo+, faithtwo+ and the faith3+. This action enhances the microbicidal effect of the mentioned agents..

As an analytical reagent

Ammonium sulfate acts as a precipitating agent in electrochemical analysis, in microbiological culture medium and in the preparation of ammonium salts..

In the precipitation and isolation of proteins

Ammonium sulfate is used in the isolation and purification of proteins, especially plasma ones. An amount of ammonium sulfate is added to the plasma to bring it to a certain concentration; thus, the precipitation of a group of proteins is caused.

The precipitate is collected by centrifugation and an additional amount of ammonium sulfate is added to the supernatant and, at a new concentration, the precipitation of another group of proteins occurs..

The repetition of the previous process in a sequential way allows as a result the obtaining of different fractions of plasmatic proteins.

Before the new technologies of molecular biology appeared, this procedure allowed the isolation of plasma proteins of great importance in medicine, for example: immunoglobulins, coagulation factors, etc..

In the industry

Ammonium sulfate acts by retarding the start of fire in the textile industry. It is used as an additive in the electroplating industry. It is also used in the production of hydrogen peroxide, ammonium chloride, etc..

Other uses

- Ammonium sulfate is used as an osmotic pressure regulating agent and as a salt precipitating agent..

- In the form of ammonium lauryl sulfate, it reduces the surface tension of the water, thus allowing the separation of contaminants by increasing the hardness of the water..

- It is an anticorrosive agent.

- It is used as a food additive that regulates the acidity in flour dough and bread.

References

  1. OECD SIDS. (October 2004). Ammonium sulfate. [PDF]. Retrieved on April 27, 2018, from: inchem.org
  2. The Mosaic Company. (2018). Ammonium sulfate. Retrieved on April 27, 2018, from: cropnutrition.com
  3. Wikipedia. (2018). Ammonium sulfate. Retrieved on April 27, 2018, from: en.wikipedia.org
  4. Pubchem. (2018). Ammonium sulfate. Retrieved on April 27, 2018, from: pubchem.ncbi.nlm.nih.gov UpSticksNGo Crew.
  5. (July 23, 2015). [Figure]. Retrieved on April 27, 2018, from: flickr.com
  6. Paula Papp. (February 22, 2017). Ammonium sulfate applications and uses. Retrieved on April 27, 2018, from: business.com

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