Chemistry

Difference Between Nitrite and Nitrate

the Basic Difference Between Nitrite and Nitrate is that Nitrite has a bent molecular geometry, form weak acid such as nitrous acids and can be oxidized to form nitrates while nitrate has trigonal planner geometry, form strong acid like nitric acid and can be reduced to form nitrites.

What are nitrate and nitrite?


Nitrates and nitrites are ions that exist naturally and are part of the nitrogen cycle. Nitrate ion (NO3) is a conjugate base of nitric acid. Nitrates are chemical compounds, salts of nitric acid. Nitrite ion (NO2) is a conjugate base of nitrous acid.

Nitrites are chemical compounds, salts or esters of nitrous acid. The nitrate ion consists of nitrogen and three oxygen atoms. The nitrogen atom is located in the center and surrounded by oxygen atoms, which are united identically in a flat trigonal conformation.

Plants and animals require nitrogen to live and grow.

However, nitrogen gas, which is abundant in the air we breathe, must first be converted into nitrogen compounds to be used as a source of nitrogen by plants and animals. This process is known as nitrogen fixation.

Nitrate and nitrite are two of the nitrogen compounds that are used by plants and animals that eventually return nitrogen in the form of gas into the air. Nitrate and nitrite can also be produced in the body.

In nature, plants use nitrate as an essential nutritional element. In commerce, most of the nitrate is used in inorganic fertilizers. Nitrate and nitrite are also used in the preservation of food, in some medicines and in the manufacture of ammunition and explosives.

The nitrite ion consists of nitrogen and two oxygen atoms. The nitrogen atom is located in the center and surrounded by oxygen atoms, which are united identically.
Natural levels of nitrates in surface and groundwater are generally a few milligrams per liter.

In many groundwaters, an increase in nitrate levels has been observed due to the intensification of agricultural and livestock practices. The concentrations can reach several hundred milligrams per liter. In some countries, up to 10% of the population may be exposed to nitrate levels in drinking water above 50 mg / l.
In general, when nitrate levels in drinking water are below 10 mg / l, the main source of nitrate intake for humans is vegetables. When nitrate levels in drinking water exceed 50 mg / l, drinking water will be the main source of total nitrate consumption.

Extensive epidemiological data support the current guideline value of 10 mg / l for nitrate-nitrogen proposed by the World Health Organization (WHO).

However, this value should not be expressed based on nitrate-nitrogen but based on nitrate itself, since it is the chemical species that present a health hazard, and the standard value for nitrate is therefore 50 mg / l.

The molar mass of the nitrate anion is 62 g / mol, while the molar mass of the nitrite anion is 46 g / mol.

Nitrates are used in agriculture, the food industry, the production of paints, medicines, plastics, glass, explosives, etc.

Nitrites are used in the production of meat and fish products.

Nitrates in the air can act as respiratory irritants. Nitrates themselves are not toxic when ingested.

Nitrification

Nitrification is the oxidation of an ammonium compound to nitrite, especially by the action of the nitrifying bacteria called Nitrosomes. The nitrites will then be oxidized to nitrates by the Nitrobacter bacteria.

Nitrate is less toxic than nitrite and is used as a food source by living plants.

The process of converting ammonium to nitrate is schematized in the nitrogen cycle.

Nitrification is faster at a pH of 7-8 and at temperatures of 25-30 ° C. Nitrification causes the pH of the water to drop.

Ecotoxicology of nitrite and nitrate

Nitrate levels greater than 0.75 ppm in water can cause stress in fish and greater than 5 ppm can be toxic.

Nitrate levels between 0 and 40 ppm are generally safe for fish. Any value greater than 80 can be toxic.

What happens to nitrate and nitrite when they enter the environment?

Nitrogen exists naturally in soils, typically linked to organic matter and minerals in the soil. The forms of nitrogen available, including nitrate and nitrite, are found in soils, water, air, and meat products.
In nature, nitrate and nitrite can be found in igneous and volcanic rocks.
The nitrate and nitrite salts dissociate completely in water.
Bacteria in the soil and plants use oxygen to convert nitrite to more stable nitrate, which can be converted back into nitrite by other bacteria when there is a shortage of oxygen.
Animal waste and nitrogen-containing fertilizers increase nitrate concentrations in the environment

How can exposure to nitrate and nitrite occur?

Nitrate and nitrite are found in the diet in vegetables (especially celery, lettuce, and spinach), fruits, cured meats, fish, dairy products, beef, and cereals.
Some meat and meat products contain nitrate or sodium nitrite as a preservative.
The body produces a certain amount of nitrate and nitrite naturally.
You may be exposed by drinking water from wells that contain nitrate that comes from sources such as animal waste runoff or fertilizer.
The release of nitrate or nitrite to soil or water in landfills can contaminate drinking water sources and increase the incorporation by plants you consume.
The inhalation of nitrate or nitrite is unlikely and is not a matter of concern for the general population, although nitrates are sometimes inhaled to relieve the pain of angina attacks

How can nitrate and nitrite affect my health?

Most people are not exposed to nitrate or nitrite levels that cause adverse effects.

Some people who ate food and drank liquids that contained unusually high levels of nitrite suffered methemoglobinemia (reduced blood’s ability to transport oxygen to tissues) and other symptoms such as a drop in blood pressure, increased heart rate, pains. head, abdominal cramps, and vomiting, some people died.

What are the chances of nitrate and nitrite causing cancer?

There is limited evidence to suggest that nitrite can cause some types of gastrointestinal cancer in humans and in mice.

The International Agency for Research on Cancer (IARC) noted that the presence of nitrite and certain types of amines or amides in the acidic environment of the stomach may result in the production of some N-nitrous compounds that cause cancer; Under these conditions, IARC determined that the ingestion of nitrate and nitrite is probably carcinogenic to humans. The EPA has not classified nitrate or nitrite in terms of carcinogenicity.

How can nitrate and nitrite affect children?

Exposure of children to excessive amounts of nitrate and/or nitrite can produce the same effects as in adults.

Babies under 6 months appeared to be especially sensitive to the effects of nitrite on hemoglobin after taking a prepared formula with drinking water that had nitrate levels higher than the recommended limit, some of these babies died.

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It is not known whether nitrate or nitrite can cause birth defects. The results of some studies suggest that the ingestion of relatively high levels of nitrate or nitrite may cause developmental disorders, but this was not observed in other studies of nitrate or nitrite.

Is there a medical test to show that I have been exposed to nitrate or nitrite?

There are methods to detect nitrate and nitrite in the blood and urine; however, these are generally not available in the doctor’s office and are also not of clinical utility.

There are routine blood tests to detect the clinical condition known as methemoglobinemia. However, these tests cannot indicate whether methemoglobinemia was caused by nitrate or nitrite or for another reason unrelated to nitrate or nitrite.

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