International name: Nitric Acid

Synonyms: strong vodka

Chemical formula: HNO3

Appearance: colorless liquid with a sharp odor

Manufacturing: Ukraine

Packing and storage: eurocube, canister 10/20 l; 3 years

 

Description

Nitric acid (HNO3) is a strong monobasic acid. Solid nitric acid forms two crystalline modifications with monoclinic and rhombic lattices. Nitric acid is mixed with water in any proportions. In aqueous solutions, it almost completely dissociates into ions. Forms with water an azeotropic mixture with a concentration of 68.4% and tcp120 ° C at normal atmospheric pressure. Two solid hydrates are known: monohydrate (HNO3 • H2O) and trihydrate (HNO3 • 3H2O).
Nitrogen in nitric acid is tetravalent [3], the degree of oxidation is +5. Nitric acid is a colorless, fuming liquid, the melting point is 41.59 ° C, boiling at +82.6 ° C (at normal atmospheric pressure) with partial decomposition. Nitric acid is mixed with water in all proportions. Aqueous solutions of HNO3 with a mass fraction of 0.95-0.98 are called "fuming nitric acid", with a mass fraction of 0.6-0.7 - concentrated nitric acid. With water, an azeotropic mixture forms (mass fraction 68.4%, d20 = 1.41 g / cm, Tc = 120.7 ° C)
Highly concentrated HNO3 usually has a brown color due to the decomposition occurring in the light.

When heated, nitric acid decomposes according to the same reaction. Nitric acid can be distilled without decomposition only under reduced pressure (this boiling point at atmospheric pressure is found by extrapolation).
Gold, some metals of the platinum group and tantalum are inert to nitric acid in the entire range of concentrations, the rest of the metals react with it, the course of the reaction is determined by its concentration.
HNO3 as a strong monobasic acid interacts.

 

Properties

Unlimitedly soluble in water with release of heat. Not flammable. Upon contact with organic substances, nitric acid causes them to self-ignition, strongly smoke.

Under the influence of nitric acid, metals (with the exception of Pt, Rh, Ir, Nb, Zr, Ta, Au) are converted to nitrates or oxides, sulfur is vigorously oxidized to sulfuric acid, phosphorus to phosphoric acid, organic compounds are oxidized and nitrated. In dilute nitric acid, the chrome-nickel steel racks, titanium, in concentrated - pure aluminum, high-silica cast iron, chromium-nickel-silicon steels. In nitric acid of any concentration, glass, quartz, and fluoroplastic are resistant.

Concentrated, not concentrated, special purity and special nitric acid are produced. Highly concentrated HNO3 usually has a brown color due to the decomposition occurring in the light.

 

Receiving

To obtain concentrated nitric acid, either equilibrium is balanced in the third reaction by increasing the pressure to 50 atmospheres, or sulfuric acid is added to dilute nitric acid and heated, while nitric acid, in contrast to water and sulfuric acid, evaporates.

Application

Nitric acid is one of the most important products of the chemical industry. For practical purposes, 30-60% aqueous solutions of nitric acid or 97-99% (concentrated nitric acid) are used.

the most important field of its application is the production of fertilizers: potassium nitrate KNO3, sodium nitrate NaNO3, ammonium nitrate NH4NO3, complex mineral fertilizers;
as a nitrating reagent in the production of explosives (trinitroglycerol, trinitrotoluene, hexogen, etc.);
as an oxidizing agent of two-component rocket fuels, for example, in a mixture with 1,1-dimethylhydrazine;
as a reagent in the nitrosic process for the production of sulfuric acid;
for obtaining nitrocellulose;
for the preparation of aromatic nitro compounds - dye precursors, pharmacological preparations and other compounds used in fine organic synthesis;
in metallurgy for etching and dissolving metals, as well as for the separation of gold and silver. A mixture of concentrated nitric and hydrochloric acids (volume ratio 1: 3) is called royal vodka, it dissolves even noble metals.
Nitric acid salts - nitrates - are widely used as fertilizers. Almost all nitrates are very soluble in water, therefore in the form of minerals, they are extremely small in nature; The exception is Chilean (sodium) nitrate and Indian nitrate (potassium nitrate). Most nitrates are produced artificially.
Nitric acid does not react with glass, fluoroplast-4.

Safety requirements

Concentrated nitric acid causes severe skin burns. Diluted acid with frequent contact with the skin can cause eczema. The affected skin is dyed yellow. If swallowed, it causes severe burns. In case of contact with skin or eyes, rinse immediately with water until acid is removed completely. When inhaled nitric acid vapor, irritation of mucous membranes, dizziness, tinnitus, drowsiness, easy swelling occur. If you inhale acid vapors, remove the victim to fresh air, give warm milk with soda or Borjomi.
Do soda inhalation, cans, mustard. When breathing gas, give oxygen.
If ingested, gastric lavage is required. Avoid emetics and solutions of carbonic acid.
Concentrated nitric acid is capable of exploding by contact with reductant substances: hydrogen sulphide, turpentine, ethanol. In contact with combustible substances, ignition may occur, accompanied by the release of toxic nitrogen dioxide, so when extinguishing a fire, a gas mask must be used.
Do not contact nitric acid with turpentine, carbides, metal powders, picric acid and chloric acid salts, formic acid, or with combustible substances. Under the influence of nitric acid, paper, oil, wood, coal burns.

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