What is ammonium sulfate or (NH4)2SO4?
By: Kakali Ghosh, Teacher Blogger. M.Sc Chemistry.
Tags: Fertilizer, Agriculture, Application, Chemistry, Ammonium Sulphate

Ammonium sulfate is an inorganic compound with chemical formula, (NH4)2SO4. It is nitrogen as well as sulfur containing manure and is predominantly used in agriculture.

Ammonium sulfate is also known as ammonium tetraoxosulfate, diammonium sulfate, mascagnite, dolamin, actamaster, sulfuric acid diammonium sulfate etc.

It is fine white hygroscopic granules or crystals and soluble in water but insoluble in acetone, ether or alcohol.

The solubility of ammonium sulfate in water increases with increase in temperature. The density of ammonium sulfate is 1.76 g/cc and it melts at 508 to 533K.

Ammonium sulfate preparation

Ammonium sulfate is prepared by treating NH3 with concentrated sulfuric acid. This reaction is carried out at a 333K fixed temperature.

Concentrated sulfuric acid is added to keep the solution acidic, and to retain its level of free acid.

2 NH3 + H2SO4 → (NH4)2SO4

Dry, powdered ammonium sulfate may be formed by spraying sulfuric acid into a reaction chamber filled with ammonia gas.

Ammonium sulfate also is manufactured from gypsum. When finely divided gypsum is added to an ammonium carbonate solution, then ammonium sulfate along with CaCO3 is obtained.

(NH4)2CO3 + CaSO4 → (NH4)2SO4 + CaCO3

Read also : What is urea fertilizer?

What Is Ammonium Sulfate Fertilizer?

Ammonium sulfate is a nitrogen and sulfur containing inorganic salt. It contains 21.2% nitrogen and 24.2% sulfur elements. It provides the nitrogen needed for plant growth.

Ammonium sulfate plays an important role to increase the acidity of alkaline soils by releasing ammonium ions and maintains the pH balance in the soil.

So ammonium nitrate is very important fertilizer and is predominantly used in agriculture for plants.

Ammonium sulfate pH

Ammonium sulfate is neither acid nor a base. It is a salt of ammonia and sulfuric acid. So on hydrolysis, ammonium sulfate produces ammonium hydroxide and H2SO4.

Now, sulfuric acid is a strong acid but NH4OH is a weak base. Hence, the aqueous solution of ammonium sulfate is overall acidic.

Consequently, the pH of (NH4)2SO4 is less than 7. It has been found that, the pH of 0.1 M ammonium sulfate solution is 5.5.

Ammonium sulfate uses

Ammonium sulfate uses in agriculture

Ammonium sulfate is a nitrogen and sulfur containing fertilizer. It contains 21.2% nitrogen and 24.2% sulfur elements.

So ammonium nitrate is very important fertilizer for plants growth. For this reason, it is predominantly used in agriculture for plants.

Generally, ammonium sulfate is used as fertilizer in alkaline soils. This is because it releases ammonium ions into the soil and forms small amounts of acid.

This maintains the pH balance in the soil. It also provides the nitrogen needed 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.

Laboratory use

Ammonium sulfate precipitation is a common method for protein purification by precipitation. It is used as an important laboratory reagent.

Ammonium sulfate is used in group analysis for group metals. In the analysis of rubber lattices, volatile fatty acids are analyzed by precipitating rubber with a 35% ammonium sulfate solution.

Ammonium sulfate use as food additive

Ammonium sulfate is used a food additive. Again, it is used as an acidity regulator in flours and breads.

Other uses

In the treatment of drinking water, ammonium sulfate is used in combination with chlorine to generate monochloramine for disinfection.

A small scale of ammonium sulfate is used in the preparation of other ammonium salts, especially ammonium persulfate. Ammonium sulfate is also used as a wood preservative.