What are Nitrates?
HNO 3 nitrate reacts with metals to form salts. Consists of metal ions (ammonium ions) and nitrate ions. Common are sodium nitrate, potassium nitrate, ammonium nitrate, calcium nitrate, lead nitrate, cerium nitrate and so on.
- Chinese name
- Nitrate
- English name
- Nitrate
- Exterior
- white
- Risk description
- Environmental pollutants
- Make up
- Metal ion and nitrate ion composition
- HNO 3 nitrate reacts with metals to form salts. Consists of metal ions (ammonium ions) and nitrate ions. Common are sodium nitrate, potassium nitrate, ammonium nitrate, calcium nitrate, lead nitrate, cerium nitrate and so on.
- On October 27, 2017, the list of carcinogens published by the International Agency for Research on Cancer of the World Health Organization initially compiled a reference, and nitrates or nitrites ingested under conditions that led to endogenous nitrosation were in the 2A carcinogens list. [1]
Introduction to Nitrate
Nitrate Overview
- Nitrate is a general term for nitric acid-derived compounds. It is generally a salt composed of metal ion or ammonium ion and nitrate ion.
- Nitrate is an ionic compound containing nitrate ion NO 3 - and corresponding positive ions, such as NH 4 + ions in ammonium nitrate.
- Common nitrates are: sodium nitrate, potassium nitrate, ammonium nitrate, calcium nitrate, lead nitrate, cerium nitrate and so on.
- Almost all nitrates are easily soluble in water, only urea nitrate is slightly soluble in water, and basic bismuth nitrate is hardly soluble in water, so the nitrate in the solution cannot be precipitated by most other cations.
Nitrate structure
- structure
- Nitrate ion, in which the nitrogen-oxygen bond is between single and double bonds.
Nitrate chemical properties
- The solid nitrate can liberate oxygen when heated. Among them, the nitrate of the most active metal releases only a part of the oxygen and turns into nitrite. .
- Nitrate is a strong oxidant in high temperature or acidic aqueous solutions, but has little oxidation in alkaline or neutral aqueous solutions.
- Nitrate and metal ions can be coordinated in a variety of ways, including monodentate, bidentate, tridentate or tip, bridge and so on.
Nitrate production method
- Nitrate exists in large quantities in nature. The main source is the formation of nitrogen-fixing bacteria and nitrogen, or nitrogen and oxygen in the air directly under the high temperature of lightning to synthesize nitrogen oxides. It dissolves in rainwater to form nitric acid, and reacts with minerals on the ground to form nitrates. .
- The simplest way to prepare nitrates is to react nitric acid with metals, metal oxides or carbonates. Certain water-containing nitrates such as Be (NO 3 ) 2 , Mg (NO 3 ) 2 and Cu (NO 3 ) 2 are hydrolyzed by heating, so corresponding anhydrous nitrates cannot be obtained. Anhydrous nitrate can be prepared by:
- Reaction in liquid N 2 O 4 :
- Ni (CO) 4 + N 2 O 4 Ni (NO 3 ) 2 + 2NO + 4CO
- Reaction in pure HNO 3 -N 2 O 5 or liquid N 2 O 5 :
- TiCl 4 + 4N 2 O 5 Ti (NO 3 ) 4 + 2N 2 O 4 + 2Cl 2
- Reacts with halogen nitrates at low temperatures. Such as chlorine nitrate ClNO 3 :
- TiCl 4 + 4ClNO 3 (-80 ) Ti (NO 3 ) 4 + 2Cl 2
- Certain metals can also form basic nitrates of the general formula MOx (NO 3 ) y, such as BiO (NO 3 ) 2 .
- Most nitrates are ionic crystals and are easily soluble in water. Some anhydrous salts are volatile.
- Nitrate can undergo decomposition reactions, and the products can be:
- Nitrite and oxygen (nitrates of alkali and alkaline earth metals);
- Metal oxides and nitrogen oxides and oxygen (nitrates between magnesium and copper);
- Elemental metals and nitrogen oxides and oxygen (metal nitrates after copper).
Nitrate use
- The main use is nitrogen fertilizer for plant absorption. Nitrogen is not only the main component of amino acids and proteins, but also synthesizes chlorophyll and promotes photosynthesis. Therefore, if the plant is deficient in nitrogen, the leaves will wither. Sodium nitrate and calcium nitrate are good nitrogen fertilizers. Potassium nitrate is the raw material for making black powder. Ammonium nitrate can be used as fertilizer or explosive. [2]
Nitrate test method
- Nitrate ions can be qualitatively detected in an acidic medium by reacting with iron (II) to produce a brown ring. See the brown ring experiment.
- The total response is:
- 3Fe 2+ + NO 3- + 4H + 3Fe 3+ + NO + 2H 2 O
- Although this reaction has a long history, the mechanism was not cleared until a systematic study of spectrophotometry and potentiometric titration not long ago: [2]
- Fe 2+ + NO 3- + 2H + Fe 3+ + NO 2 + H 2 O
- Fe 2+ + NO 2 + H + Fe 3+ + HNO 2
- Fe 2+ + HNO 2 + H + Fe 3+ + NO + H 2 O
- Fe 2+ + NO FeNO 2 +
- 2NO 2 + H 2 O HNO 2 + NO 3- + H +
- 2HNO 2 NO + NO 2 + H 2 O
- NO + NO 3- + H + NO 2 + HNO 2
- The brown ring is caused by FeNO 2 + (step 4), and the quick control step is the last step.
The harm of nitrate to the environment
- Nitrate (NO 3- ) and nitrite (NO 2- ) are the acid radicals of nitric acid (HNO 3 ) and nitrous acid (HNO 2 ), respectively. They exist widely in nature as environmental pollutants, especially in the gaseous state. In water, surface water and groundwater, and in plants and animals and food. There are many sources of nitrate and nitrite pollution in the environment, such as:
- 1. Artificial fertilizers: ammonium nitrate, calcium nitrate, potassium nitrate, sodium nitrate, urea, etc. 2. Domestic sewage, domestic waste and human and animal waste, according to tests, 1 liter of domestic sewage can produce 110 mg of nitrate during natural degradation ; 1 kg of garbage manure compost can produce 492 mg of nitrate after leaching and decomposition under natural conditions; 3. Food, fuel, oil refining and other factories emit a large amount of ammonia-containing waste, and nitrate is formed after biological and chemical conversion Enter the environment; 4. Automobiles, trains, ships, airplanes, boilers, and civilian furnaces burn petroleum fuels, coal, and natural gas, which can generate a large amount of nitrogen oxides, and burn an average of 1 ton of coal, 1,000 liters of oil, and 10,000 cubic meters. Natural gas can produce 9, 13 and 63 kilograms of nitrogen dioxide gas, respectively. These nitrogen dioxide gas can form nitrate and fall to the ground and water after leaching; 5. Food preservation and preservation: nitrate and nitrite are It is widely used in the preservation and preservation of meat and fish to make meat products appear red and scented.
- Drinking water, vegetables, food, fish, meat products, pickled vegetables, overnight cooking, etc. containing a large amount of nitrates and nitrites can be directly poisoned by people, and nitrates can also be in the human body. Reduction to nitrite. Nitrite interacts with the human blood to form methemoglobin, which causes the blood to lose its oxygen carrying function, making people hypoxic and poisoning. Those who are light-headedness, palpitations, vomiting, lips cyanosis, and those who are unconscious, convulsions, shortness of breath, rescue Delays can be life threatening. Not only that, nitrite interacts with secondary amines inside and outside the human body to form nitrosamines [3] , which are carcinogenic, teratogenic and mutagenic when it reaches a certain dose in the human body, which can seriously endanger human health. In order to prevent the harm of nitrate and nitrite, in addition to the scientific and rational application of chemical fertilizers, the prohibition of sewage irrigation, the implementation of environmentally friendly treatment of sewage, garbage and feces, and other environmental protection measures to protect surface water and groundwater sources from nitrate and In addition to nitrate pollution, you should also try to eat less cured, smoked, and cured fish, meat, sausages, bacon, ham, canned food, pickled vegetables, and short-salted vegetables. Stir-fried vegetables; eat the same day; finish eating the same day; do not eat overnight cooked vegetables; do not store leftovers for a long time; do not accidentally eat industrial nitrite (such as sodium nitrite) as salt.