[Chemistry Class Notes] on Difference between Nitrate and Nitrite Pdf for Exam

Nitrate and nitrite are the naturally occurring ions that are part of the nitrogen cycle. These are used interchangeably due to their similar pronunciation and spelling. Both of them are inorganic compounds composed of oxygen and nitrogen. 

 

In general, naturally occurring nitrate levels in groundwater and surface are a few milligrams per liter. If considered with many groundwaters, we can observe an increase of nitrate levels because of the intensification of farming practice. Also, the concentrations can reach several hundred milligrams per liter. In a few of the countries, up to 10% of the population may be exposed to nitrate levels of above 50 mg/l in drinking water.

 

It is said that vegetables will be the main source of nitrate intake for humans when drinking water levels are below 10 mg/l. The time when the concentration of nitrate in drinking water exceeds 50 mg/l, then the drinking water will be the primary source of total nitrate intake.

 

Effects of Nitrate and Nitrite when They Enter The Environment

Naturally, nitrogen exists in soils, typically bound to mineral soil material and organic matter. The available forms of nitrogen, including nitrite and nitrate, are present in water, soils, plants, and meat products.

 

Nitrate and nitrite are found naturally in igneous and volcanic rocks. Also, salts of these naturally occurring ions completely dissolve in water.

 

Bacteria present in plants and soils use oxygen to change the nitrite into more stable nitrate, which is converted back to nitrite by other bacterial forms when there is a lack of oxygen. Nitrogen-containing fertilizers and animal wastes increase the concentration of nitrate in the environment.

 

Structures of Nitrate and Nitrite

Both nitrate and nitrite are interchangeably used because they have similarities in their spelling and pronunciation. Both of them are inorganic compounds composed of oxygen and nitrogen. The difference in the shape, structure, and function depends on the number of oxygen atoms they bring out. Nitrates have one nitrogen and three oxygen atoms, where nitrites have one nitrogen and two oxygen atoms.

 

Nitrate

Anion is a conjugate base of nitric acid, containing a central nitrogen atom surrounded by three identically oxygen atoms bonded in a trigonal planar arrangement where the nitrate ion is carried by a formal charge of −1. This charge results from the combination of the formal charge in which each of the three oxygens carries a − 2⁄3 charge, while the nitrogen carries a +1 charge, all of which add up to the formal charge of the polyatomic nitrate ion. This arrangement is also seen as a resonance example.

 

Similar to the isoelectronic carbonate ion, nitrate ions can be indicated by the resonance structures.

 

 

Nitrite

Nitrite ions contain a symmetrical structure (C2v symmetry), with both N–O bonds having equal length and bond angle of 115°. According to the valence bond theory, it is described as the resonance hybrid with equal contributions from two canonical forms, which are mirror images of each other. In a molecular orbital theory, there consists of a sigma bond between each nitrogen and oxygen atom, and a delocalized pi bond is made from the ‘p’ orbitals on both oxygen and nitrogen atoms, which is perpendicular to the molecule plane. The negative ion charge is distributed equally on the two oxygen atoms. Since both oxygen and nitrogen atoms carry a lone pair of electrons, the nitrite ion is a Lewis base.

 

 

If we think about what is the difference between nitrate and nitrite, the significant ones that one can remember are tabulated below.

 

Differences Between Nitrite and Nitrate

 

Effect of Nitrate and Nitrite on Children

Children can experience similar effects as adults when overexposed to nitrate or nitrite.

 

Young infants who are less than six months of age appeared to be particularly sensitive to nitrite effects on hemoglobin after consuming the formula prepared with drinking water that contained nitrate at levels higher than recommended limits, and some of these infants died.

 

Still, it is not disclosed whether nitrate or nitrite can cause birth defects. Few studies suggest that intake of relatively high levels of nitrite or nitrate could cause developmental effects, but at the same time, other studies found no evidence for this.

 

For such reasons, it is highly recommended not to use the food or water products on the children, especially before six months of age because they encounter severe further health problems or they may affect them immediately.