Nitrates

Nitrogen and oxygen combine to form nitrates, an inorganic chemical with the formula NO3 (one molecule nitrogen and three molecules of oxygen). Sodium and potassium nitrates can be made by combining these molecules with additional elements such as sodium and potassium. Unless it is converted to nitrite, nitrate is not typically harmful to human health.

Description

Chemical Name- Nitrate

Regulatory Name- Nitrate

Molecular formula- NO3–

Molecular Weight- 62 g/mol

Definition of nitrates

According to the International Union of Pure and Applied Chemistry (IUPAC), polyatomic ions that include nitrogen and oxygen are called nitrates. In the absence of a proton, the nitrate anion is produced. The chemical formula of nitrate is NO3– and it may be found in nature.  

Nitrate ions combine to form nitrate salts. The nitrate ion’s conjugate base is nitric acid, also known as nitrite. Nucleic acid (nitrate) has three identical oxygens on either side of a nitrogen atom in the centre. This element has a Trigonal planar arrangement in its structure. Nitrogen atoms are charged at +1, and each of the three oxygens is charged at half of that. Therefore, the net charge of the nitrate ion is equal to one. 

The nitrate anion is formed when the formal charge of the nitrate ion joins with these. Similar to the isoelectronic carbonate ion, the nitrate ion shows resonance.

Chemical properties of nitrates

Molecular weight (molar mass) : 62.005 g/mol

Number of Hydrogen bond donors : 0

Number of Hydrogen bond Acceptor : 3

The number of rotatable bonds : 0

Topological polar surface area : 62.9 A2

Number of covalent bonds : 1

Heavy atom count : 4

Isotope atom count : 0

Resonance Structure: 

O– – N – O–                                O–  – N = :O:                   :O: = N – O–

         ||                                               |                                           |

        :O:                                     O–                                O–

Uses of nitrates

Due to their high solubility and biodegradability, nitrates are primarily generated for use as fertilisers in agricultural production. Ammonium, sodium, potassium, calcium and magnesium salts are the most often used nitrate fertilisers. Many million kg of sugar is produced each year to meet this need. 

Another important use of nitrates is as oxidising agents, most notably in explosives where the quick oxidation of carbon compounds results in the release of enormous quantities of gases (gunpowder, for example). 

Sodium nitrate is used to eliminate air bubbles from molten glass and certain ceramics, and it also has other applications. The hardening of various metals is accomplished by the use of molten salt mixtures. Because of the high combustibility of the original safety film, the studios switched to acetate safety film in 1950.

Occurrence and production

A significant source of sodium nitrate is found in nitratine, a naturally occurring salt found in dry parts of the world. Nitrate salts, particularly nitratine, can be found in large quantities in dry environments. In the natural world, nitrifying bacteria employ ammonia or urea as a source of nitrogen and oxygen to do this work, creating nitrates in the process. In the past, nitrate compounds for gunpowder were made via fermentation procedures involving urine and dung due to a lack of easily available mineral nitrate sources. In Earth’s nitrogen- and oxygen-rich atmosphere, thunderstorms create a mixture of nitrogen oxides that combine to generate nitrous ions and nitrate ions, which are either washed out of the atmosphere by rain or deposited as deposition of acid compounds and other pollutants.  

In industrial contexts, nitric acid is used to make nitrates.

Health effects of nitrate:

Nitrate is one of the most common groundwater contaminants in rural regions. It has to be controlled in drinking water, primarily because high levels of methaemoglobin, often known as “blue baby” illness, can result from exposure to excessive amounts. 

When it comes to older children and adults, elevated levels of nitrates are not a health hazard; nevertheless, these suggest the presence of other more hazardous home or agricultural contaminants, such as bacteria or pesticides.

Conversion of nitrite to nitrate

Nitrification is the process of converting nitrite to nitrate. It is an aerobic process. Ammonia is oxidised physically to nitrite, which then oxidises to nitrate through oxidation. The process of “nitrification” is vital in the nitrogen cycle. Nitrification is carried out by archaea and autotrophic bacteria. After ammonia oxidation, bacteria work their magic to convert nitrite to nitrate. Proteobacteria, Nitrospirae, and Chloroflexi are examples. These bacteria can be found in geothermal springs, soil, marine ecosystems, and freshwater.

The chemical process of nitrite to nitrate conversion:

Ammonia is first transformed to nitrites (NO2–) and subsequently to nitrates in the process of nitrification. This reaction, known as nitritation, is carried out by Nitrosomonas, a bacterium commonly found in soil. Nitrosomonas convert ammonia (NH3) to nitrogen dioxide (NO2) during the process of nitritation (nitrogen dioxide). 

NH3 + 1.5 O2 → NO2–  +  H+  +  H20

Nitration is the second step in the nitrification procedure. This process is completed by an enzyme known as nitrite-oxidoreductase (NOR).

 NO2–  +  ½ O2 → NO3

Ammonia, the organic form of nitrogen, is transformed into nitrate, the inorganic form of nitrogen, which plants may utilise when both of these steps are complete.

2NO3 + 3O2 → 2NO2 + 2H+ + 2H2O

Conclusion

Nitrates are often found in groundwater and surface water, but high quantities can be harmful to human health. Bad well construction, fertiliser usage, poor well location, or improper animal or human waste disposal can cause nitrate contamination. The concentration of nitrate in the solution increases as water evaporates, making it more challenging to remove nitrate by heating or boiling the solution. Nitrate cannot be removed from water by chlorination or mechanical filtering. Reverse osmosis, anion exchange, and distillation can successfully remove water-borne nitrate.