Urea Definition -CH4N2O

Urea, also popularly known as Carbamide, is the diamide form of carbonic acid. Urea is widely used as a fertilizer, a feed supplement, and a starting material in the manufacture of drugs and plastics. It is a colorless substance existing in the crystalline form, which melts at 132.7°C (271° F) and which decomposes even before the Urea boiling point. Urea is also the chief end product of the metabolic protein breakdown in all the mammals and few fishes. It doesn’t just occur in the urine of the mammals but also in their milk, bile, blood, and perspiration. 

During the procedure of protein breakdown, all the amino groups (NH2) are naturally removed from the amino acids which contain proteins. These groups are further converted into Ammonia (NH3), which is toxic to the body. In order to protect the body from it, it is converted to urea by the human liver. The urea is further passed through the kidneys and is excreted in the form of urine. 

History and Synthesis of Urea

Urea was separated from urine by Hilaire Marin Rouelle, a French chemist back in 1773.  Later in 1828, Friedrich Wohler, a German chemist, started its official preparation from Ammonium Cyanate. This process is accepted as a laboratory synthesis of this naturally existing organic compound from all the inorganic materials. Urea is then commercially prepared in larger amounts from both liquid carbon dioxide and liquid ammonia. These materials when combined under elevated temperature and high pressure to form Ammonium Carbamate, decompose at lower pressure to give water and urea.

Urea Structure

Urea is a waste product in the body with no physiological function. It dissolves in the kidney and blood before it is excreted as urine. The organic compound of Urea has two different NH2 groups that are connected by the carbonyl functional group. Urea is non-toxic, which is why it dissolves in water. Apart from being colorless, it also has no smell.

In urea, the carbonyl group is attached to two amide groups. This is where it got the name carbamide, which is formed from carboxylic+amide. A carbonyl group is where a carbon atom is double-bonded to an oxygen atom. An amide group is where a nitrogen atom is attached to two different hydrogen atoms. When you put two such amide groups bonded with the carbonyl group, urea is formed. To write the formula, the atoms that urea contain are:

  • 1 Carbon

  • 1 Oxygen

  • 2 Nitrogen

  • 4 Hydrogen

Urea structural Formula

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Urea Formula and Structure



Molecular Weight/ CH4N2O Molar Mass/ Urea Mass

60.06 g/mol


1.32 g/cm3


White solid

Melting Point

133 °C

How is Urea Produced?

The kidneys, lungs, and skin are the important excretory organs in the body. In other words, they are the only organs that can remove the toxins and the toxic products from the body. The lungs are responsible for getting rid of excess carbon dioxide, while the skin removes excess salts and water. The kidneys, on the other hand, also remove excess salts, water, and Urea. The Urea, which is formed when the dietary proteins are turned into amino acids during digestion, are sent to the liver. The liver breaks down all the excess acids to ammonia and further converts it into urea, which is relatively less toxic.

Properties of Urea

Urea consists of Nitrogen, Carbon, and Oxygen. As mentioned, you can find it in the milk, blood, and sweat of mammals. When in concentrated form, it is turned into urine. Urea is basically a crystalline compound whose nitrogen content is around 46%, in the dry state. About 1 million pounds of urea is processed in the United States every year. Most of it is used in the fertilizers to make their nitrogen content, water-soluble. Urea is also used in plastics and glues, animal feedstock, expensive commercial products, and explosive components. 

Urea Uses - What Is Urea Used For?

  • It is mainly used as a nitrogen release fertilizer to make the product water-soluble.

  • Urea is used as a stabilizer in most of the nitrocellulose explosive products.

  • It is used in manufacturing high explosive materials like urea nitrate (CH5N3O4)

  • It is used as an important reagent in lanthanide chemistry.

  • It is used in creams/ointments that are used for rehydration.

  • It is used in hair removal creams and dish soaps.

  • It is used as a browning agent for pretzels.

  • It is used in manufacturing melamine.

  • It is used to detect the bacteria in the stomach through the urea breath test.

Synthetic Urea Definition – How is Urea Formed – Preparation of Urea

In 1828, Urea was first artificially synthesized through a scientific breakthrough from inorganic compounds. The chemical compound urea is made by combining ammonia and carbon dioxide (Ammonium Carbamide)  in high pressure and high-temperature reactor.  

2NH3 + CO2 ⇋ NH2COONH4 (ammonium carbamate)

NH2COONH4 ⇋ H2O + NH2CONH2 (urea)

The heat then further dehydrates the compound to form Urea, a crystalline compound.

FAQ (Frequently Asked Questions)

1. Is uric acid the same as urea?

Mammals such as humans and animals create urea while reptiles, birds, and invertebrates create uric acid as waste. These uricothelic beings excrete waste in the form of white powder or paste. When compared, converting ammonia in to uric acid requires a lot more energy than the energy required for converting ammonia into urea. 

2. Is Urea good for skin?

Urea, which contains the carbamide, can be used as medication when applied to the skin. Through Urea, you can treat itching and dryness in cases of dermatitis, ichthyosis, and psoriasis. It can also be used to soften the nails and for loosening dried skin. However, when used excessively, it can also cause skin irritation.

3. How long does urea take to act in a fertilizer?

If the soil is dry, you won't be able to see any reaction. But with the urease and soil moisture, urea hydrolyzes itself and converts into carbon dioxide and ammonium. The whole process takes around 2-4 days, especially on the high pH soils. However, one has to be careful about the soil before using urea in it. To make things easier, a soil test has to be conducted prior.