Nitric acid is a strong acid with strong oxidation and corrosiveness. Chemical formula: HNO 3. Melting point: - 42 C, boiling point: 78 C, soluble in water, at room temperature pure nitric acid solution colorless and transparent.

Nitric acid is unstable. Nitrogen dioxide is released when it is decomposed by light or heat. Nitrogen dioxide produced by decomposition is dissolved in nitric acid, so that it has a light yellow appearance. It should be stored in a dark place in brown bottle, or in a frosted plastic bottle (not recommended). Contact with reducing agent is strictly prohibited.

Concentrated nitric acid is a strong oxidant, which can cause combustion when exposed to organic substances, sawdust, etc. Concentrated nitric acid containing trace oxides can react with almost all metals except aluminium and chromium-containing special steels, while the passivation of aluminium and chromium-containing special steels by concentrated nitric acid reacts violently with ethanol, turpentine, coke and organic residue. Nitric acid is mainly produced by ammonia oxidation process in industry to produce fertilizers, explosives, nitrates, etc. In organic chemistry, the mixture of concentrated nitric acid and concentrated sulfuric acid is an important nitrating reagent. The chemical formula is HNO 3. A mixture of concentrated hydrochloric acid and concentrated nitric acid can be made into strong corrosive aqua regia with a volume ratio of 3:1. The anhydride of nitric acid is nitrogen pentoxide (N2O5).

application area

1. As the necessary raw material of nitrate and nitrate ester, nitric acid is used to produce a series of nitrate nitrogen fertilizers, such as ammonium nitrate, potassium nitrate, etc., and also to produce nitrate or nitro-containing explosives.

2. Because nitric acid is both oxidizing and acidic, nitric acid is also used to refine metals: that is, impurity metal is oxidized to nitrate first, impurities are removed and then reduced. Nitric acid can passivate iron without further corrosion. It can also be used for making nitrogen fertilizer, Aqua regia, nitrate, nitroglycerin, nitrocellulose, nitrobenzene, picric acid, etc.

3. Nitroglycerin will be formed when glycerin is released into concentrated nitric acid and sulfuric acid. This is a colorless or yellow transparent oily liquid. It is a very unstable substance. When it is impacted, it will decompose, produce high temperature, and produce a large number of gases at the same time. The volume of the gas expands suddenly, causing a violent explosion. So nitroglycerin is a powerful explosive.

4. Nitro-explosives are mostly used in military affairs as 2,4,6-trinitrotoluene (TNT). It is made of toluene, concentrated nitric acid and concentrated sulfuric acid. It is a yellow flake. It has the advantages of high explosive power, stable explosive property and low hygroscopicity. It is commonly used as explosive for shells, grenades, mines and torpedoes. It can also be used in blasting operations such as mining. Organic synthetic raw materials, concentrated nitric acid can nitrate benzene, anthracene, naphthalene and other aromatic compounds to produce organic raw materials. For example, the mixed acid of nitric acid and sulphuric acid (which is commonly used in industry to react with benzene to form nitrobenzene and then hydrogenate to aniline) is an intermediate in the synthesis of dyes, medicines and pesticides. Oxalic acid is produced by reacting crop wastes such as corn stamens, bagasse, grain husks and peanut hulls with nitric acid to produce oxalic acid. Oxalic acid can also be produced by reacting nitric acid with propylene or ethylene or ethylene glycol.

Matters needing attention

operation

Closed operation, pay attention to ventilation. The operation is as mechanized and automated as possible. Operators must be specially trained and strictly abide by the operating rules. Operators are advised to wear self-priming filter gas mask (full cover), rubber acid and alkali resistant clothing and rubber acid and alkali resistant gloves. Keep away from fire and heat sources. Smoking is strictly prohibited in the workplace. Prevent steam from leaking into the air of the workplace. Avoid contact with reductants, alkalis, alcohols and alkali metals. Handling should be light loading and unloading to prevent damage to packaging and containers. Equipped with the corresponding variety and quantity of fire fighting equipment and leakage emergency treatment equipment. Empty containers may retain harmful substances. When diluting or preparing solution, acid should be added to water to avoid boiling and splashing.

Storage

Store in a cool, ventilated warehouse. Keep away from fire and heat sources. Storage temperature does not exceed 30 C and relative humidity does not exceed 80%. Keep the container sealed. It should be stored separately with reducing agent, alkali, alcohols and alkali metals. Mixed storage should not be avoided. The storage area shall be equipped with emergency leak handling equipment and suitable storage materials.

transport

Railway tanker loading, in which lead tanker used to transport 98% concentrated nitric acid, dilute nitric acid used stainless steel or FRP reinforced plastic tanker or storage tank transportation or storage. A small amount is packed in acid-resistant ceramic jars or glass bottles, with net weight of 33-40 kg per jar. Concentrated nitric acid is sealed with acid-resistant mud and dilute nitric acid is sealed with gypsum. Each jar is packed in a solid wooden box lined with fine cinder or slag for transportation. There should be a clear mark of 'corrosive articles' on the package. Aluminum is an ideal container for nitric acid because of its passivation and economy with an oxide film on its surface. Individual protection prohibits direct contact with skin, and acid and alkali resistant gloves, masks and other labor insurance products should be worn during operation.

Human impact

Nitric acid is oxidative and corrosive in both concentrated and dilute solutions, so it is dangerous to people and can cause serious burns if only splashed on the skin. When the skin is exposed to nitric acid, it will turn yellow slowly, and eventually the yellowing skin will peel off (after nitric acid and protein contact, it will cause lutein reaction and denaturation). In addition, concentrated nitric acid should be filled in dark glass bottles to avoid the release of toxic NO2 by light reaction.