Urea

Urea is a natural compound and is the main solid component of urine in humans and most mammals. Urea is formed in the liver and excreted out of the human body through the kidney.

Properties
Urea can be found in two different physical states, a solid or a liquid. It is regularly translucent; appearing to be colorless, or a light brown, yellowish color. As for the odor of urea, there generally is none. But if one can smell a scent from urea, it will generally smell a little bit like ammonia. Urea has a density of about 1.33g/cm3. At room temperature, somewhere around sixty-eight degrees Fahrenheit or twenty degrees Celsius, the specific gravity of urea will be 1.34. Being that its specific gravity is at 1.34, urea is heavier than water; this will cause it to sink when it is in water. Also, the molecular mass, or molar mass of urea is 60.06 grams. In order to decompose urea, one would have to heat it to 270.8 degrees Fahrenheit, or 132.7 degrees Celsius. When burned at this temperature, urea will emit small amounts of nitrogen oxides. Urea decomposes into ammonia and carbon dioxide.

Synthesis
When urea is synthesized, it requires both ammonia and carbon dioxide. While at high temperatures and pressures, the ammonia and carbon dioxide are placed inside of a reactor. Then a two step reaction takes place: 2NH3 + CO2 ! NH2COONH4 (ammonium carbamate) NH2COONH4 ! H2O + NH2CONH2 (urea). Once the pressure is reduced and the heat is applied, the NH2COONH4 decomposes to NH2 and CO2. The urea will then be put into granuals, and the ammonia and carbon dioxide will be recycled.

Uses
Urea is primarily used as fertilizer. Over the past decade it has surpassed ammonia nitrate as the leading substance in fertilizers. Urea is known to have 46 percent nitrogen. This is why many farmers want to use it as a fertilizer. It can be applied to the crops that a farmer owns through either a solid, a solution, or as in a foliar spray. A big benefit of urea as a fertilizer is that it exhibits little to no fire or explosion hazard. Also the manufacture of urea causes very few pollutants into the environment. Because it is non combustible and non explosive urea can be stored for long periods of time. It can be stored for a long time with barely any loss to the quality of the urea under regular circumstances.

Bodily Function
Urea is the main compound found in the waste product of many living organisms. It is the main component of a human's urine. When the human body breaks down amino acids, which are proteins, the amino acids are converted into ammonia, carbon dioxide, and water. But the ammonia is toxic to the human body's cells, therefor it must be removed. So the liver converts the ammonia into a different non-toxic product called urea. The urea is then safely transported in the blood through the kidneys. Then finally the urea can be excreted out of the body through urine. On average, a normal healthy adult will excrete about 25 grams of urea each day. Once the urea goes stale, bacteria will turn it back into ammonia which gives urine its putrid smell.

Video
The urea cycle in the human body AoBbVu5rnMs