Ammonium sulfate
Encyclopedia
Ammonium sulfate (N
H
4)2S
O
4, is an inorganic salt with a number of commercial uses. The most common use is as a soil fertilizer. It contains 21% nitrogen as ammonium
cations, and 24% sulfur as sulfate
anions. In fertilizer the purpose of the sulfate is to reduce the soil pH
.
for alkaline soils. In the soil the ammonium
ion is released and forms a small amount of acid, lowering the pH
balance of the soil
, while contributing essential nitrogen
for plant growth.
It is also used as an agricultural spray adjuvant
for water soluble insecticide
s, herbicide
s, and fungicide
s. 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 protein
s by selective precipitation; Ammonium sulfate is extremely soluble in water and so can make very concentrated solutions which can "salt out" proteins, causing their precipitation at particular concentrations. This provides a convenient and simple means to fractionate complex protein mixtures . As such, 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.
A saturated solution of ammonium sulfate in heavy water
(2H2O) is used as an external standard in sulfur (33S) NMR spectroscopy
with shift value of 0 ppm.
It has also been used in flame retardant
compositions acting much like Diammonium phosphate
. As a flame retardant, it lowers the combustion temperature of the material, decreases maximum weight loss rates, and causes an increase in the production of residue or char.
In November 2009, a ban on ammonium sulfate, ammonium nitrate and calcium ammonium nitrate
fertilizers was imposed in the former Malakand Division
- comprising the Upper Dir, Lower Dir, Swat, Chitral
and Malakand
districts of the North West Frontier Province (NWFP) of Pakistan
, by the NWFP government, following reports that those chemicals were used by militants to make explosives. In January 2010, these substances were also banned in Afghanistan
for the same reason.
(or by-product ammonia from coke-ovens) with sulfuric acid
:
A mixture of ammonia gas and water vapor is introduced into a reactor that contains a saturated solution of ammonium sulfate and about 2 to 4% of free sulfuric acid at 60 °C. Concentrated sulfuric acid is added to keep the solution acidic, and to retain its level of free acid. The heat of reaction keeps reactor temperature at 60 °C.
Dry, powdered ammonium sulfate may be formed by spraying sulfuric acid into a reaction chamber filled with ammonia gas
. The heat of reaction evaporates all water
present in the system, forming a powdery salt.
Ammonium sulfate also is manufactured from gypsum
(CaSO4·2H2O). Finely divided gypsum is added to an ammonium carbonate
solution. Calcium carbonate
precipitates out, leaving ammonium sulfate in the solution.
Ammonium sulfate occurs naturally as the rare mineral mascagnite
in volcanic fumarole
s and due to coal fires on some dumps.
. Heating at higher temperature result in fully decomposition into ammonia
, nitrogen
, sulfur dioxide
and water. As a salt of a strong acid (i.e. H2SO4) and weak base (i.e. NH3), its solution is acidic; pH of 0.1M solution is 5.5.
In aqueous solution the reactions are those of NH4+ and SO4−2 ions. For example, addition of barium chloride
, precipitates out barium sulfate
. The filtrate on evaporation yields ammonium chloride
.
Ammonium sulfate forms many double salts (ammonium metal sulfates) when its solution is mixed with equimolar solutions of metal sulfates and the solution is slowly evaporated. Such double metal sulfates include ammonium cobaltous sulfate, ferric ammonium sulfate
, ammonium nickel sulfate and ammonium cerous sulfate
.
Nitrogen
Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...
H
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...
4)2S
Sulfur
Sulfur or sulphur is the chemical element with atomic number 16. In the periodic table it is represented by the symbol S. It is an abundant, multivalent non-metal. Under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S8. Elemental sulfur is a bright yellow...
O
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
4, is an inorganic salt with a number of commercial uses. The most common use is as a soil fertilizer. It contains 21% nitrogen as ammonium
Ammonium
The ammonium cation is a positively charged polyatomic cation with the chemical formula NH. It is formed by the protonation of ammonia...
cations, and 24% sulfur as sulfate
Sulfate
In inorganic chemistry, a sulfate is a salt of sulfuric acid.-Chemical properties:...
anions. In fertilizer the purpose of the sulfate is to reduce the soil pH
Soil pH
The soil pH is a measure of the acidity or basicity in soils. pH is defined as the negative logarithm of the activity of hydrogen ions in solution. It ranges from 0 to 14, with 7 being neutral. A pH below 7 is acidic and above 7 is basic. Soil pH is considered a master variable in soils as it...
.
Uses
It is used largely as an artificial fertilizerFertilizer
Fertilizer is any organic or inorganic material of natural or synthetic origin that is added to a soil to supply one or more plant nutrients essential to the growth of plants. A recent assessment found that about 40 to 60% of crop yields are attributable to commercial fertilizer use...
for alkaline soils. In the soil the ammonium
Ammonium
The ammonium cation is a positively charged polyatomic cation with the chemical formula NH. It is formed by the protonation of ammonia...
ion is released and forms a small amount of acid, lowering the pH
PH
In chemistry, pH is a measure of the acidity or basicity of an aqueous solution. Pure water is said to be neutral, with a pH close to 7.0 at . Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are basic or alkaline...
balance of the soil
Soil
Soil is a natural body consisting of layers of mineral constituents of variable thicknesses, which differ from the parent materials in their morphological, physical, chemical, and mineralogical characteristics...
, while contributing essential nitrogen
Nitrogen
Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...
for plant growth.
It is also used as an agricultural spray adjuvant
Adjuvant
An adjuvant is a pharmacological or immunological agent that modifies the effect of other agents, such as a drug or vaccine, while having few if any direct effects when given by itself...
for water soluble insecticide
Insecticide
An insecticide is a pesticide used against insects. They include ovicides and larvicides used against the eggs and larvae of insects respectively. Insecticides are used in agriculture, medicine, industry and the household. The use of insecticides is believed to be one of the major factors behind...
s, herbicide
Herbicide
Herbicides, also commonly known as weedkillers, are pesticides used to kill unwanted plants. Selective herbicides kill specific targets while leaving the desired crop relatively unharmed. Some of these act by interfering with the growth of the weed and are often synthetic "imitations" of plant...
s, and fungicide
Fungicide
Fungicides are chemical compounds or biological organisms used to kill or inhibit fungi or fungal spores. Fungi can cause serious damage in agriculture, resulting in critical losses of yield, quality and profit. Fungicides are used both in agriculture and to fight fungal infections in animals...
s. 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
Biochemistry
Biochemistry, sometimes called biological chemistry, is the study of chemical processes in living organisms, including, but not limited to, living matter. Biochemistry governs all living organisms and living processes...
, ammonium sulfate precipitation
Ammonium sulfate precipitation
Ammonium sulfate precipitation is a method used to purify proteins by altering their solubility. It is a specific case of a more general technique known as salting out....
is a common method for purifying protein
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
s by selective precipitation; Ammonium sulfate is extremely soluble in water and so can make very concentrated solutions which can "salt out" proteins, causing their precipitation at particular concentrations. This provides a convenient and simple means to fractionate complex protein mixtures . As such, 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.
A saturated solution of ammonium sulfate in heavy water
Heavy water
Heavy water is water highly enriched in the hydrogen isotope deuterium; e.g., heavy water used in CANDU reactors is 99.75% enriched by hydrogen atom-fraction...
(2H2O) is used as an external standard in sulfur (33S) NMR spectroscopy
NMR spectroscopy
Nuclear magnetic resonance spectroscopy, most commonly known as NMR spectroscopy, is a research technique that exploits the magnetic properties of certain atomic nuclei to determine physical and chemical properties of atoms or the molecules in which they are contained...
with shift value of 0 ppm.
It has also been used in flame retardant
Flame retardant
Flame retardants are chemicals used in thermoplastics, thermosets, textiles and coatings that inhibit or resist the spread of fire. These can be separated into several different classes of chemicals:...
compositions acting much like Diammonium phosphate
Diammonium phosphate
Diammonium phosphate is one of a series of water-soluble ammonium phosphate salts which can be produced when ammonia reacts with phosphoric acid...
. As a flame retardant, it lowers the combustion temperature of the material, decreases maximum weight loss rates, and causes an increase in the production of residue or char.
In November 2009, a ban on ammonium sulfate, ammonium nitrate and calcium ammonium nitrate
Calcium ammonium nitrate
Calcium ammonium nitrate, often abbreviated CAN, is a fertilizer which is a blend of about 20%-30% CaCO3 and 70%-80% Ammonium nitrate. It is used as a general plant fertilizer. It is an example for nitrogenous fertiliser.-References:Ammonium nitrate...
fertilizers was imposed in the former Malakand Division
Malakand Division
Malakand Division was an administrative division of the North West Frontier Province of Pakistan, until the reforms of 2000 abolished the third tier of government....
- comprising the Upper Dir, Lower Dir, Swat, Chitral
Chitral
Chitral or Chetrar , translated as field in the native language Khowar, is the capital of the Chitral District, situated on the western bank of the Kunar River , in Pakistan. The town is at the foot of Tirich Mir, the highest peak of the Hindu Kush, high...
and Malakand
Malakand District
Malakand District is a district of the province of Khyber Pakhtunkhwa in Pakistan.The District was formed in 1970 as a Provincially Administered Tribal Area, It had previously been a Tribal Area known as the Malakand Protected Area, part of the Malakand Agency...
districts of the North West Frontier Province (NWFP) of Pakistan
Pakistan
Pakistan , officially the Islamic Republic of Pakistan is a sovereign state in South Asia. It has a coastline along the Arabian Sea and the Gulf of Oman in the south and is bordered by Afghanistan and Iran in the west, India in the east and China in the far northeast. In the north, Tajikistan...
, by the NWFP government, following reports that those chemicals were used by militants to make explosives. In January 2010, these substances were also banned in Afghanistan
Afghanistan
Afghanistan , officially the Islamic Republic of Afghanistan, is a landlocked country located in the centre of Asia, forming South Asia, Central Asia and the Middle East. With a population of about 29 million, it has an area of , making it the 42nd most populous and 41st largest nation in the world...
for the same reason.
Preparation
Ammonium sulfate is made by reacting synthetic ammoniaAmmonia
Ammonia is a compound of nitrogen and hydrogen with the formula . It is a colourless gas with a characteristic pungent odour. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. Ammonia, either directly or...
(or by-product ammonia from coke-ovens) with sulfuric acid
Sulfuric acid
Sulfuric acid is a strong mineral acid with the molecular formula . Its historical name is oil of vitriol. Pure sulfuric acid is a highly corrosive, colorless, viscous liquid. The salts of sulfuric acid are called sulfates...
:
- 2 NH3 + H2SO4 → (NH4)2SO4
A mixture of ammonia gas and water vapor is introduced into a reactor that contains a saturated solution of ammonium sulfate and about 2 to 4% of free sulfuric acid at 60 °C. Concentrated sulfuric acid is added to keep the solution acidic, and to retain its level of free acid. The heat of reaction keeps reactor temperature at 60 °C.
Dry, powdered ammonium sulfate may be formed by spraying sulfuric acid into a reaction chamber filled with ammonia gas
Ammonia
Ammonia is a compound of nitrogen and hydrogen with the formula . It is a colourless gas with a characteristic pungent odour. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. Ammonia, either directly or...
. The heat of reaction evaporates all water
Water
Water is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...
present in the system, forming a powdery salt.
Ammonium sulfate also is manufactured from gypsum
Gypsum
Gypsum is a very soft sulfate mineral composed of calcium sulfate dihydrate, with the chemical formula CaSO4·2H2O. It is found in alabaster, a decorative stone used in Ancient Egypt. It is the second softest mineral on the Mohs Hardness Scale...
(CaSO4·2H2O). Finely divided gypsum is added to an ammonium carbonate
Ammonium carbonate
Ammonium carbonate is a commercial salt with the chemical formula 2CO3. It is used when crushed as a smelling salt. It can be crushed when needed in order to revive someone who has fainted...
solution. Calcium carbonate
Calcium carbonate
Calcium carbonate is a chemical compound with the formula CaCO3. It is a common substance found in rocks in all parts of the world, and is the main component of shells of marine organisms, snails, coal balls, pearls, and eggshells. Calcium carbonate is the active ingredient in agricultural lime,...
precipitates out, leaving ammonium sulfate in the solution.
- (NH4)2CO3 + CaSO4 → (NH4)2SO4 + CaCO3
Ammonium sulfate occurs naturally as the rare mineral mascagnite
Mascagnite
Mascagnite is a rare ammonium sulfate mineral 2SO4. It crystallizes in the orthorhombic system typically forming as stalactitic masses exhibiting good cleavage. It is soft and water soluble...
in volcanic fumarole
Fumarole
A fumarole is an opening in a planet's crust, often in the neighborhood of volcanoes, which emits steam and gases such as carbon dioxide, sulfur dioxide, hydrochloric acid, and hydrogen sulfide. The steam is created when superheated water turns to steam as its pressure drops when it emerges from...
s and due to coal fires on some dumps.
Reactions
Ammonium sulfate decomposes upon heating above 250°C, firstly forming ammonium bisulfateAmmonium bisulfate
Ammonium bisulfate, also known as ammonium hydrogen sulfate, is a white, crystalline solid when it is completely pure, with formula HSO4. It is commonly collected as a byproduct of flue gas desulfurization, formed by partial neutralization of sulfuric acid aerosols by gaseous ammonia, NH3. ...
. Heating at higher temperature result in fully decomposition into ammonia
Ammonia
Ammonia is a compound of nitrogen and hydrogen with the formula . It is a colourless gas with a characteristic pungent odour. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. Ammonia, either directly or...
, nitrogen
Nitrogen
Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...
, sulfur dioxide
Sulfur dioxide
Sulfur dioxide is the chemical compound with the formula . It is released by volcanoes and in various industrial processes. Since coal and petroleum often contain sulfur compounds, their combustion generates sulfur dioxide unless the sulfur compounds are removed before burning the fuel...
and water. As a salt of a strong acid (i.e. H2SO4) and weak base (i.e. NH3), its solution is acidic; pH of 0.1M solution is 5.5.
In aqueous solution the reactions are those of NH4+ and SO4−2 ions. For example, addition of barium chloride
Barium chloride
Barium chloride is the inorganic compound with the formula BaCl2. It is one of the most common water-soluble salts of barium. Like other barium salts, it is toxic and imparts a yellow-green coloration to a flame. It is also hygroscopic....
, precipitates out barium sulfate
Barium sulfate
Barium sulfate is the inorganic compound with the chemical formula BaSO4. It is a white crystalline solid that is odorless and insoluble in water. It occurs as the mineral barite, which is the main commercial source of barium and materials prepared from it...
. The filtrate on evaporation yields ammonium chloride
Ammonium chloride
Ammonium chloride NH4Cl is an inorganic compound with the formula NH4Cl. It is a white crystalline salt that is highly soluble in water. Solutions of ammonium chloride are mildly acidic. Sal ammoniac is a name of natural, mineralogical form of ammonium chloride...
.
Ammonium sulfate forms many double salts (ammonium metal sulfates) when its solution is mixed with equimolar solutions of metal sulfates and the solution is slowly evaporated. Such double metal sulfates include ammonium cobaltous sulfate, ferric ammonium sulfate
Mohr's salt
Ammonium iron sulfate, or Mohr's Salt, is the inorganic compound with the formula 2Fe2·6H2O. Containing two different cations, Fe2+ and NH4+, it is classified as a double salt of ferrous sulfate and ammonium sulfate. It is a common laboratory reagent...
, ammonium nickel sulfate and ammonium cerous sulfate
Ammonium cerium(IV) sulfate
Ammonium cerium sulfate, is a chemical compound. It is frequently used as an oxidising agent in titrations. The orange-colored cerium ion is reduced to the colorless cerium ion. The potential for reduction is high, about +1.44V. Cerium sulfate is also used.Ammonium cerium sulfate is a very safe...
.
Further reading
- Properties: UNIDO and International Fertilizer Development Center (1998), Fertilizer Manual, Kluwer Academic Publishers, ISBN 0-7923-5032-4.