urea resume

UREA DISCRIPTION

Urea or carbamide is an organic compound with the chemical formula (NH2)2CO. The molecule has two amine (-NH2) groups joined by a carbonyl (C=O) functional group. Urea serves an important role in the metabolism of nitrogen-containing compounds by animals and is the main nitrogen-containing substance in the urine of mammals. It is solid, colourless, and odorless (although the ammonia which it gives off in the presence of water, including water vapor in the air, has a strong odor). It is highly soluble in water and non-toxic. Dissolved in water it is neither acidic nor alkaline. The body uses it in many processes, most notably nitrogen excretion. Urea is widely used in fertilizers as a convenient source of nitrogen. Urea is also an important raw material for the chemical industry. The synthesis of this organic compound by Friedrich Wöhler in 1828 from an inorganic precursor was an important milestone in the development of organic chemistry, as it showed for the first time that a molecule found in living organisms could be synthesized in the lab without ...

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Industrial methods

For use in industry, urea is produced from synthetic ammonia and carbon dioxide. Large quantities of carbon dioxide are produced during the manufacture of ammonia from coal or from hydrocarbons such as natural gas and petroleum-derived raw materials. Such point sources of CO₂ facilitate direct synthesis of urea.
The basic process, developed in 1922, is also called the Bosch-Meiser urea process after its discoverers. The various urea processes are characterized by the conditions under which urea formation takes place and the way in which unconverted reactants are further processed. The process consists of two main equilibrium reactions, with incomplete conversion of the reactants. The first is an exothermic reaction of liquid ammonia with dry ice to form ammonium carbamate (H₂N-COONH₄):

2 NH₃ + CO₂ ↔ H₂N-COONH₄ ()

The second is an endothermic decomposition of ammonium carbamate into urea and water:

H₂N-COONH₄ ↔ (NH₂)₂CO + H₂O

Both reactions combined are exothermic.
Unconverted reactants can be used for the manufacture of other products, for example ammonium nitrate or sulfate, or they can be recycled for complete conversion to urea in a total-recycle process.
Urea can be produced as prills, granules, pellets, crystals, and solutions. Solid urea is marketed as prills or granules. The advantage of prills is that, in general, they can be produced more cheaply than granules. Properties such as impact strength, crushing strength, and free-flowing behaviour are, in particular, important in product handling, storage, and bulk transportation.
Typical impurities in the production are biuret and isocyanic acid:

2 NH₂CONH₂ → H₂NCONHCONH₂ + NH₃

NH₂CONH₂ → HNCO + NH₃

The biuret content is a serious concern because it is often toxic to the very plants that are to be fertilized. Urea is classified on the basis of its biuret content.