Ammonium Sulfate – (NH4)2SO4, 7783-20-2

Ammonium sulfate ((NH4)2SO4) is a widely used fertilizer that provides essential nutrients to plants. It is also used in flame retardants, protein purification, and as a food additive.

IUPAC nameAmmonium tetraoxosulfate (VI) 
Molecular formula(NH4)2SO4
CAS number7783-20-2 
SynonymsAmmonium sulphate, Ammonium sulfate (2:1), Diammonium sulfate, Sulfuric acid diammonium salt, Mascagnite, Actamaster, Dolamin
InChIInChI=1S/2H3N.H2O4S/c;;1-5(2,3)4/h2*1H3;(H2,1,2,3,4)

Ammonium Sulfate Properties

Ammonium Sulfate Formula

The formula for ammonium sulfate is (NH4)2SO4. This means that one molecule of ammonium sulfate contains two ammonium ions (NH4)+ and one sulfate ion (SO4)2-. The ammonium ions and the sulfate ion are held together by ionic bonds.

Ammonium Sulfate Molar Mass

The molar mass of (NH4)2SO4 is 132.14 g/mol. To calculate the molar mass, we need to add up the atomic masses of all the atoms in the formula. The atomic masses are:

  • Nitrogen: 14.01 g/mol
  • Hydrogen: 1.01 g/mol
  • Sulfur: 32.06 g/mol
  • Oxygen: 16.00 g/mol

So, the molar mass of (NH4)2SO4 is:

(2 x 14.01) + (8 x 1.01) + 32.06 + (4 x 16.00) = 132.14 g/mol

Ammonium Sulfate Boiling Point

The boiling point of (NH4)2SO4 is not well-defined because it decomposes before reaching a boiling point. When heated above 235 °C, (NH4)2SO4 starts to lose water and form ammonium bisulfate (NH4)HSO4. When heated above 280 °C, ammonium bisulfate further decomposes into ammonia (NH3) and sulfuric acid (H2SO4).

Ammonium Sulfate Melting Point

The melting point of (NH4)2SO4 is 235 °C. This is the temperature at which (NH4)2SO4 changes from a solid to a liquid state. However, as mentioned above, (NH4)2SO4 also starts to decompose at this temperature, so it is not a pure liquid phase.

Ammonium Sulfate Density g/ml

The density of (NH4)2SO4 is 1.77 g/ml at room temperature and pressure. This means that one milliliter of (NH4)2SO4 weighs 1.77 grams. The density of a substance depends on its temperature and pressure, so it may change slightly under different conditions.

Ammonium Sulfate Molecular Weight

The molecular weight of (NH4)2SO4 is the same as its molar mass, which is 132.14 g/mol. The molecular weight is the mass of one mole of a substance, which is equal to 6.022 x 10^23 molecules. The molecular weight can also be expressed in atomic mass units (amu), which are equal to 1/12 of the mass of a carbon-12 atom. In amu, the molecular weight of (NH4)2SO4 is 132.14 amu.

Ammonium Sulfate Structure

Ammonium Sulfate

The structure of (NH4)2SO4 can be represented by a Lewis dot structure or a ball-and-stick model. A Lewis dot structure shows the valence electrons of each atom and the bonds between them. A ball-and-stick model shows the shape and size of each atom and the bonds between them.

In the above structure, the double lines (=) represent double bonds, the single lines (-) represent single bonds, and the dots (.) represent lone pairs of electrons.

Ammonium Sulfate Solubility

The solubility of (NH4)2SO4 is the amount of (NH4)2SO4 that can dissolve in a given amount of water at a given temperature. The solubility of (NH4)2SO4 increases with increasing temperature, as shown by the following data:

Temperature (°C)Solubility (g/100 ml water)
070.6
AppearanceFine white hygroscopic granules or crystals
Specific gravity1.77
ColorWhite
OdorOdorless
Molar mass132.14 g/mol
Density1.77 g/cm3
Melting point235 to 280 °C (decomposes)
Boiling pointNot applicable (decomposes)
Flash pointNon-flammable
Water solubility70.6 g per 100 g water (0 °C), 74.4 g per 100 g water (20 °C), 103.8 g per 100 g water (100 °C)
SolubilityInsoluble in acetone, alcohol and ether
Vapour pressureNegligible
Vapour densityNot applicable
pKa5.5 (for ammonium ion)
pH5 to 6 (for 5% solution)

Ammonium Sulfate Safety and Hazards

(NH4)2SO4 is not very hazardous to human health, but it can cause irritation to the skin, eyes, nose and throat if in contact or inhalation. It can also cause nausea, stomach pain, diarrhea, vomiting and drowsiness if swallowed. It is harmful to aquatic life and should be avoided from releasing to the environment. It decomposes when heated above 235 °C, forming toxic gases such as ammonia and sulfuric acid. It is generally recognized as safe as a food additive, but it may cause allergic reactions or asthma symptoms in some people.

Hazard symbolsNone required
Safety descriptionAvoid release to the environment. Dispose of contents/container to an approved waste disposal plant.
UN IDsNot applicable
HS code31022100
Hazard classNot applicable
Packing groupNot applicable
ToxicityLD50 (oral, rat) = 2840 mg/kg

Ammonium Sulfate Synthesis Methods

One can synthesize (NH4)2SO4 by various methods as it is an inorganic salt. Some of the common methods are:

  • Neutralization of ammonia and sulfuric acid: This method involves mixing ammonia gas or aqueous solution with sulfuric acid and evaporating the water to obtain (NH4)2SO4 crystals.

2 NH3 + H2SO4 -> (NH4)2SO4

(NH4)2CO3 + CaSO4 -> (NH4)2SO4 + CaCO3

  • By-product of other processes: Various industrial processes, such as coke oven gas purification, caprolactam production, nickel refining, and flue gas desulfurization, can produce (NH4)2SO4 as a by-product. These processes use ammonia or ammonium compounds to remove sulfur or other impurities from the gas streams, resulting in (NH4)2SO4 as a waste or a valuable product.

Ammonium Sulfate Uses

(NH4)2SO4 is an inorganic salt that has various uses, such as:

  • Fertilizer for alkaline soils: (NH4)2SO4 lowers the pH of the soil and provides nitrogen and sulfur for plant growth. It is suitable for crops that need acidic soil conditions, such as blueberries, potatoes, and tomatoes.
  • Agricultural spray adjuvant: (NH4)2SO4 enhances the effectiveness of water-soluble insecticides, herbicides, and fungicides by binding iron and calcium ions that can interfere with their action. It also improves the uptake of glyphosate and other systemic herbicides by plants.
  • Protein purification: (NH4)2SO4 can precipitate proteins from aqueous solutions by increasing the ionic strength and reducing the solubility of proteins. One can use the salting out method to separate proteins based on their size, charge, and hydrophobicity.
  • Food additive: Various food products like bread, cheese, wine, and canned vegetables use (NH4)2SO4 as an acidity regulator, dough conditioner, yeast nutrient, and firming agent. The FDA recognizes it as generally safe.
  • Other uses: One can use (NH4)2SO4 for manufacturing other ammonium salts, fire extinguishers, flame retardants, leather tanning, dyeing textiles, electroplating metals, and performing analytical chemistry.

Questions:

Q: What is the chemical formula for ammonium sulfate?

A: The chemical formula for ammonium sulfate is (NH4)2SO4. It means that one molecule of ammonium sulfate contains two ammonium ions (NH4)+ and one sulfate ion (SO4)2-.

Q: Is ammonium sulfate soluble?

A: (NH4)2SO4 is soluble in water, but insoluble in acetone, alcohol and ether. It can dissolve 70.6 grams per 100 grams of water at 0 °C, 74.4 grams per 100 grams of water at 20 °C, and 103.8 grams per 100 grams of water at 100 °C.

Q: How much ammonium sulfate per gallon of water?

A: The amount of (NH4)2SO4 per gallon of water depends on the desired concentration and the temperature of the water. For example, if the desired concentration is 10% (w/v) and the temperature of the water is 20 °C, then the amount of (NH4)2SO4 per gallon of water is:

10% (w/v) = 10 grams per 100 ml of water 1 gallon = 3785.41 ml 10 grams x 3785.41 ml / 100 ml = 378.54 grams Therefore, the amount of (NH4)2SO4 per gallon of water is 378.54 grams.

Q: Does a reaction occur when aqueous solutions of ammonium sulfate and calcium chloride are combined?

A: No, a reaction does not occur when aqueous solutions of (NH4)2SO4 and calcium chloride are combined. This is because both salts are soluble in water and do not form any insoluble precipitate. The resulting solution contains four ions: ammonium (NH4)+, sulfate (SO4)2-, calcium (Ca2+) and chloride (Cl)-.

Q: How to precipitate proteins with ammonium sulfate?

A: To precipitate proteins with (NH4)2SO4, the following steps can be followed:

  • Prepare an aqueous solution of (NH4)2SO4 with a known concentration and volume.
  • Add the protein solution to the (NH4)2SO4 solution slowly and with stirring.
  • Monitor the turbidity or optical density of the mixture to determine the amount of protein precipitation.
  • Centrifuge the mixture to separate the protein pellet from the supernatant.
  • Discard the supernatant and wash the protein pellet with a buffer or water to remove excess salt.
  • Resuspend or solubilize the protein pellet in a suitable buffer for further analysis or use.

Q: How many grams in 6.90 molecules of ammonium sulfate?

A: To find out how many grams in 6.90 molecules of (NH4)2SO4, we need to use the Avogadro’s number and the molar mass of (NH4)2SO4. The Avogadro’s number is 6.022 x 10^23, which means that one mole of any substance contains that many molecules. The molar mass of (NH4)2SO4 is 132.14 g/mol, which means that one mole of (NH4)2SO4 weighs that many grams. Therefore, we can use this formula to calculate how many grams in 6.90 molecules of (NH4)2SO4:

grams = molecules x molar mass / Avogadro’s number grams = 6.90 x 132.14 / 6.022 x 10^23 grams = 1.52 x 10^-21 Therefore, there are 1.52 x 10^-21 grams in 6.90 molecules of (NH4)2SO4.

Q: How much sulfur in ammonium sulfate?

A: (NH4)2SO4 contains 24% sulfur by mass. This can be calculated by using the percentage composition formula and the molar masses of sulfur and (NH4)2SO4. The molar mass of sulfur is 32.06 g/mol and the molar mass of (NH4)2SO4 is 132.14 g/mol. Therefore, the percentage of sulfur in (NH4)2SO4 is:

percentage = molar mass of sulfur x 100 / molar mass of ammonium sulfate percentage = 32.06 x 100 / 132.14 percentage = 24.26%

Q: Which of these is a neutral salt? na2so4 nacn kf (nh4)2so4

A: A neutral salt is a salt that does not affect the pH of the solution when dissolved in water. It is formed by the reaction of a strong acid and a strong base. Out of the four salts given, only na2so4 is a neutral salt. It is formed by the reaction of sodium hydroxide (a strong base) and sulfuric acid (a strong acid). The other salts are either acidic or basic. Nacn is a basic salt, formed by the reaction of sodium hydroxide (a strong base) and hydrocyanic acid (a weak acid). Kf is a basic salt, formed by the reaction of potassium hydroxide (a strong base) and hydrofluoric acid (a weak acid). (Nh4)2so4 is an acidic salt, formed by the reaction of ammonium hydroxide (a weak base) and sulfuric acid (a strong acid).

Q: What is the molar mass of (nh4)2so4?

A: The molar mass of (nh4)2so4 is 132.14 g/mol. To find the molar mass, we need to add up the atomic masses of all the atoms in the formula. The atomic masses are:

  • Nitrogen: 14.01 g/mol
  • Hydrogen: 1.01 g/mol
  • Sulfur: 32.06 g/mol
  • Oxygen: 16.00 g/mol

So, the molar mass of (nh4)2so4 is:

(2 x 14.01) + (8 x 1.01) + 32.06 + (4 x 16.00) = 132.14 g/mol

Q: Is (nh4)2so4 soluble in water?

A: Yes, (nh4)2so4 is soluble in water. It can dissolve up to 70.6 grams per 100 grams of water at 0 °C, 74.4 grams per 100 grams of water at 20 °C, and 103.8 grams per 100 grams of water at 100 °C.