Nitric acid is a corrosive, toxic liquid that can cause severe burns. It is used to make explosives like nitroglycerin and trinitrotoluene (TNT), as well as fertilizers like ammonium nitrate.
Summary
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- 1 History
- 2 Physical properties
- 3 Obtaining
- 4 Applications
- 5 Risks
- 1 To health
- 6 Home treatment
- 7 Storage
- 8 External links
- 9 Source
- 10 Bibliographic Reference
History
Nitric acid was first prepared in 1648 from Potassium Nitrate by Glauber. In 1783 , Covendish managed to determine its composition. Nitric acid was known to alchemists who called it aqua fortis. It is the most important oxacid in nitrogen and probably the second most important (after sulfuric) of all inorganic acids. It is a colorless, oily liquid that, due to the action of light, takes on a more or less intense brown color, due to its partial decomposition in NO 2 (its solutions must be stored in dark bottles):
Physical properties
Nitric acid is found in the atmosphere after thunderstorms. Pure Nitric Acid is a colorless and odorless, viscous liquid, it decomposes slowly by the action of light, assuming a yellow coloration due to the NO 2 produced in the reaction. In the humid air it emits white fumes. its melting point is -43 ºC and its boiling point is 83 ºC but its decomposition is accentuated at that temperature. It is soluble in water in any proportion and quantity and its density is 1.5 g / ml. Often different impurities color it yellow-brown. At room temperature it releases red or yellow fumes. Concentrated nitric acid stains human skin yellow on contact, due to a reaction with Cysteine present in the keratin of the skin.
Heated decomposes:
4 HNO 3 ——— 4NO 2 + 2H 2 O + O 2
In this decomposition an oxidation-reduction is verified.
4N + 4e – —– 4N (reduction)
2O – 4e — O2 (oxidation)
The nitrogen passes pentavalent in nitric acid in tetravalent nitrogen dioxide reduced, and oxygen passes combined to free rusting. This decomposition is produced more slowly by light, therefore, nitric acid must be stored in ground jars. The glittering vapors dissolve in the acid, communicating the same Brown Red coloration. It is a Monoprotic acid: It only forms neutral salts:
Nitrates.
HNO 3 – [H] +1 (ac) + [NO 3 ] -1 (ac)
Obtaining
- a) In the Laboratory: treating SodiumNitrate with concentrated sulfuric acid. One of Bertholet’s rules applies here, since sulfuric acid is more fixed than nitric acid.
NaNO 3 + H 2 SO 4 = NaHSO 4 + HNO 3
If the temperature rises:
NaHSO 4 + NaNO 3 = Na 2 SO 4 + HNO 3
Adding both reactions:
2 NaNO 3 + H2SO 4 = Na 2 SO 4 + 2 HNO 3
Industrial Method: Oswald Synthesis Pre-heated ammonia and air vapors are passed through a platinum mesh at 1000 ° C.
4NH 3 + 5O 2 = 4NO + 6 H 2 O
This gas passes to metallic absorption towers where this other reaction occurs:
2 NO + O 2 = 2 NO2
This nitrogen dioxide with water forms:
3 NO 2 + H 2 O = 2HNO 3 + NO
Nitric oxide returns to give the reaction:
2 NO + O 2 = 2 NO 2
Applications
HNO3 is one of the most important acids from the point of view of industrial life, since it is consumed in large quantities in the industry of fertilizers, dyes, explosives, manufacturing of sulfuric acid, medicines and metal engraving. It is used, in some cases, in the passivation process of metals, it is also used to check gold and platinum. Due to its oxidizing action, it is used in many processes and due to the nitrating action in the dye industry. In the manufacture of fertilizers The methods of fixing atmospheric nitrogen (Birbeland-Eyde procedure) and those studied for ammonia (Haber), complemented in the Osdwald synthesis, They have enormous industrial importance and in particular for agriculture, since the natural reserves of natural fertilizers such as saltpeter are insufficient to satisfy the needs of crops, so the use of atmospheric nitrogen solved a problem of capital interest by supplying mineral nitrates in large quantities. quantities and at low cost. As a nitrating agent in the manufacture of explosives. The modern explosives that have replaced the old black powder are nitrate derivatives obtained by the action of nitric acid on some organic substance: with cotton it forms Cotton Powder or nitrocellulose and is used for collodion and celluloid. With Toluene it gives rise to the formation of TRINITROTOLUENO (TNT) or Trotyl. It is used to prepare Nitrobenzene, the base of aniline. With glycerin it constitutes Nitroglycerin, which mixed with porous earth constitutes lac. Nitric acid is used in artistic engraving (etching) It is prepared with the pyric acid and Silver Nitrate used in thephotography . It forms with hydrochloric acid and with sulfuric acid the list of acids with the greatest industrial application.
Risks
It can generate very toxic nitrogen oxides when heated. As it is a strong oxidant, its contact with combustible material increases the risk of fire or even explosion.
It is non-combustible, but it is dangerously reactive with many materials. Reacts explosively with metal powders, carbides, hydrogen sulfide, alcohol and carbon. Increases the flammability of organic fuels and oxidized materials, which can cause ignition. With water and steam, it generates heat and corrosive and poisonous fumes. With powerful reducing agents, it explodes. In general, avoid humidity, heat and contact with the compounds mentioned in the chemical properties.
To health
This product is mainly irritating and causes burns and ulceration of all the tissues with which it is in contact. The extent of the damage, the signs and symptoms of poisoning, and the treatment required depend on the concentration of the acid, the time of exposure, and the susceptibility of the individual. The minimum lethal dose is approximately 5 ml (concentrate) for a 75 kg person. People with skin, eye and cardiopulmonary problems are at great risk when working with this product. Inhalation: An acute inhalation of this product produces sneezing, hoarseness, laryngitis, breathing problems, irritation of the respiratory tract and chest pain.
In extreme cases, bleeding from the nose, ulceration of the mucosa of the nose and mouth, pulmonary edema, chronic bronchitis and pneumonia occur. Severe signs of intoxication appear 5 to 48 h after exposure, having breathed at least 25 ppm in a period of 8 h. Even deaths have been reported immediately after serious exposure to NO 2 vapors . It also causes tooth erosion under prolonged periods of exposure.
Eye contact: Produces irritation, pain, tearing, corneal erosion and even blindness.
Skin contact: For the skin, it is dangerous both liquid and vapor. It causes severe burns, the skin turns yellow, and pain and dermatitis occur. Ingestion: This acid is highly corrosive and can destroy gastrointestinal tissues. The main symptoms of intoxication from ingestion of this acid are: salivation, intense thirst, difficulty swallowing, pain and shock. Burns occur in the mouth, esophagus and stomach, there is stomach pain and weakening. In case of vomiting, this is generally brown. If the amount ingested is large, a circulatory collapse may occur.
Carcinogenicity: Cases have been reported in which it is related to vapors of this acid along with traces of carcinogenic metals and asbestos with laryngeal cancer. Mutagenicity: There is no information in this regard. Reproductive Hazards: Teratogenic and reproductive effects have been found in laboratory experiments.
Home treatment
Seek immediate medical assistance and NOT make a person throw up unless told to do so by poison control or a professional health .
If the person swallowed the chemical, give them a small amount of water or milk immediately, unless the doctor has given other instructions. Give her 4 to 6 oz. (120 to 180 ml) of magnesia milk, if possible.
Do not give milk or water if the patient has symptoms that make swallowing difficult, such as vomiting, seizures, or decreased alertness.
If the person inhaled the poison, move it immediately to a place where you can get fresh air.
Storage
Store in cool, dry and well ventilated places. Stay away from alkalis, metals, organic products, oxidizable material and, in general, from the products mentioned in the Chemical Properties. Nitric acid in all its concentrations must be stored in stainless steel drums and tanks, but if the concentration is greater than 80% it can be done in aluminum containers . For small quantities, glass containers protected with metal cans and packed in wooden boxes or barrels can be used.
