Ammonium sulfate

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Ammonium sulfate
Ammonium sulfate.png
IUPAC name Ammonium sulfate
Other names ammonium sulfate (2:1);
diammonium sulfate;
sulfuric acid diammonium salt;
CAS number [7783-20-2]
SMILES [O-]S([O-])(=O)=O.[NH4+].[NH4+]
Molecular formula (NH4)2SO4
Molar mass 132.14 g/mol
Appearance Fine white hygroscopic granules or crystals.
Density 1.77 g/cm³ @ 50 °C (122 °F)
Melting point

235-280 °C, 508-553 K, 455-536 °F (decomposes)

Solubility in water 70.6 g/100 mL (0 °C) and
103.8 g/100 mL (100 °C)[1]
Critical relative humidity 79.2% at 30 °C
Related Compounds
Related compounds Ammonium iron sulfate
Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)

Ammonium sulfate is an inorganic chemical compound with the chemical formula (NH4)2SO4. It contains 21 percent nitrogen in the form of ammonium ions and 24 percent sulfur as sulfate ions. The purified material takes the form of white granules or crystals. It is commonly used as a fertilizer and as an agricultural spray adjuvant for water soluble pesticides. It is also used in the preparation of other ammonium salts.


Occurrence in nature

Ammonium sulfate occurs naturally as the rare mineral mascagnite in volcanic fumaroles and due to coal fires on some dumps.[2]


Ammonium sulfate is a salt of ammonia and sulfuric acid, and its chemical formula is (NH4)2SO4. Under standard conditions of temperature and pressure, it takes the form of fine white granules or crystals. It is not soluble in alcohol or liquid ammonia. It is slightly hygroscopic, absorbing water from the air at relative humidity above 81 percent (at about 20 °C).


Ammonium sulfate is prepared commercially by reacting ammonia with sulfuric acid (H2SO4). Ammonium sulfate is prepared commercially from the ammoniacal liquor of gas-works and is purified by recrystallization. It forms large, rhombic prisms, has a somewhat saline taste and is easily soluble in water. The aqueous solution on boiling loses some ammonia and forms an acid sulfate.


Ammonium sulfate is used largely as an artificial fertilizer for alkaline soils. In the soil, the sulfate ion is released and forms sulfuric acid, lowering the pH balance of the soil (as do other sulfate compounds such as aluminum sulfate), while contributing essential nitrogen for plant growth.

In addition, it is used as an agricultural spray adjuvant for water soluble insecticides, herbicides, and fungicides. There it functions to bind iron and calcium cations that are present in both well water and plant cells. It is particularly effective as an adjuvant for 2,4-D (amine), glyphosate, and glufosinate herbicides.

It is also used in the preparation of other ammonium salts.

In biochemistry, ammonium sulfate precipitation is a common method for purifying proteins by precipitation. As such, ammonium sulfate is also listed as an ingredient in many vaccines used in the United States, according to the Centers for Disease Control and Prevention (CDC).[3]

Ammonium sulfate is also a food additive.[4]

See also


  1. Handbook of Chemistry and Physics
  2. Mascagnite Retrieved October 9, 2008.
  3. Vaccine Excipient & Media Summary, Part 2 Centers for Disease Control and Prevention. Retrieved October 9, 2008.
  4. Lower-Carb Italian Herb Bread Retrieved October 9, 2008.


  • Brown Jr., Theodore L., H. Eugene LeMay, Bruce Edward Bursten, and Julia R. Burdge. 2002. Chemistry: The Central Science, 9th ed. Upper Saddle River, NJ: Prentice Hall. ISBN 0130669970
  • Chang, Raymond. 2006. Chemistry, 9th ed. New York, NY: McGraw-Hill Science/Engineering/Math. ISBN 0073221031
  • Havlin, John L., Samuel L. Tisdale, James D. Beaton, and Werner L. Nelson. 2004. Soil Fertility and Fertilizers: An Introduction to Nutrient Management, 7th ed. Upper Saddle River, NJ: Pearson Prentice Hall. ISBN 0130278246
  • International Fertilizer Development Center, and United Nations Industrial Development Organization. 1998. Fertilizer Manual. Dordrecht: Kluwer Academic. ISBN 0792350324
  • Moore, John W., Conrad L. Stanitski, and Peter C. Jurs. 2005. Chemistry: The Molecular Science, 2nd ed. Belmont, CA: Thompson Brooks/Cole. ISBN 9780534422011
  • Walters, Charles. 2003. Eco-farm: An Acres U.S.A. Primer. Austin, TX: Acres U.S.A. ISBN 0911311742

External links

All links retrieved September 29, 2012.


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