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Ammonium sulfate

Ammonium sulfate
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)

Infobox disclaimer and references

Ammonium sulphate, ((NH4)2SO4), is an inorganic chemical compound commonly used as a fertilizer. It contains 21% nitrogen as ammonia and 24% sulphur as sulphate. Its molecular formula is closely related to salt an ammonium sulphate analogue with an iron atom within the compound.

Additional recommended knowledge



Ammonium sulfate is not soluble in alcohol or liquid ammonia. The compound is slightly hygroscopic and absorbs water from the air at relative humidity > 81% (at ca. 20°C).


Ammonium sulphate is prepared commercially by reacting ammonia with sulfuric acid (H2SO4). Ammonium sulphate is prepared commercially from the ammoniacal liquor of gas-works and is purified by recrystallisation. 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 sulphate.


It 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 aluminium sulphate), while contributing essential nitrogen for plant growth.

It is also 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.

Ammonium Sulfate is also listed as an ingredient for many United States vaccines per the Center for Disease Control.

Ammonium Sulfate is also a food additive.

ammonium sulfate is used to quickly put a patina on copper surfaces.

Further reading

  • Properties: UNIDO and International Fertilizer Development Center (1998), Fertilizer Manual, Kluwer Academic Publishers, ISBN 0-7923-5032-4.
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Ammonium_sulfate". A list of authors is available in Wikipedia.
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