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Nitric acid



 
 
Nitric acid (H
Hydrogen

Hydrogen is the chemical element with atomic number 1. It is represented by the chemical symbol H. At standard temperature and pressure, hydrogen is a colorless, odorless, nonmetallic, tasteless, highly combustion and explosive Diatomic molecule gas with the molecular formula H2....
NO3
Nitrate

In inorganic chemistry, a nitrate is a salt of nitric acid with an ion composed of one nitrogen and three oxygen atoms . In organic chemistry the esters of nitric acid and various alcohols are called nitrates....
), also known as aqua fortis
Aqua fortis

Aqua fortis, or "strong water," in alchemy, is a corrosive solution of nitric acid in water. It is made from Potassium nitrate. It was used in alchemy as a solvent for dissolving silver and most other metals with notable exceptions of gold and platinum that can be dissolved using aqua regia....
and spirit of nitre, is a highly corrosive
Corrosion

Corrosion means the breaking down of essential properties in a material due to chemical reactions with its surroundings. In the most common use of the word, this means a loss of electrons of metals reacting with water and oxygen....
 and toxic strong acid
Strong acid

A strong acid is an acid that ionizes completely in an aqueous solution , or in other terms, with a acid dissociation constant < -1.74. This generally means that in aqueous solution at standard temperature and pressure, the concentration of hydronium ions is equal to the concentration of strong acid introduced to the solution....
 that can cause severe burns.

Colorless when pure, older samples tend to acquire a yellow cast due to the accumulation of oxides of nitrogen
Nitrogen oxide

The term nitrogen oxide typically refers to any binary compound of oxygen and nitrogen, or to a mixture of such compounds:* Nitric oxide , nitrogen oxide...
. If the solution contains more than 86% nitric acid, it is referred to as fuming nitric acid. Fuming nitric acid is characterized as white fuming nitric acid
White fuming nitric acid

White fuming nitric acid is a storable liquid oxidizer used with kerosene and hydrazine rocket fuel. It consists of nearly pure nitric acid . WFNA is commonly specified as containing no more than 2% water and less than 0.5% solution nitrogen dioxide or dinitrogen tetroxide....
 and red fuming nitric acid
Red fuming nitric acid

Red fuming nitric acid is a storable oxidizer used as a rocket propellant. It consists mainly of nitric acid , also containing 13% dinitrogen tetroxide and 3% water....
, depending on the amount of nitrogen dioxide
Nitrogen dioxide

Nitrogen dioxide is the chemical compound with the chemical formula NitrogenOxygen2. One of several nitrogen oxides, NO2 is an intermediate in the industrial synthesis of nitric acid, millions of tons of which are produced each year....
 present.

anhydrous nitric acid (100%) is a colorless liquid with a density of 1522 kg/m³ which solidifies at -42 °C to form white crystals and boils at 83 °C.






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Nitric acid (H
Hydrogen

Hydrogen is the chemical element with atomic number 1. It is represented by the chemical symbol H. At standard temperature and pressure, hydrogen is a colorless, odorless, nonmetallic, tasteless, highly combustion and explosive Diatomic molecule gas with the molecular formula H2....
NO3
Nitrate

In inorganic chemistry, a nitrate is a salt of nitric acid with an ion composed of one nitrogen and three oxygen atoms . In organic chemistry the esters of nitric acid and various alcohols are called nitrates....
), also known as aqua fortis
Aqua fortis

Aqua fortis, or "strong water," in alchemy, is a corrosive solution of nitric acid in water. It is made from Potassium nitrate. It was used in alchemy as a solvent for dissolving silver and most other metals with notable exceptions of gold and platinum that can be dissolved using aqua regia....
and spirit of nitre, is a highly corrosive
Corrosion

Corrosion means the breaking down of essential properties in a material due to chemical reactions with its surroundings. In the most common use of the word, this means a loss of electrons of metals reacting with water and oxygen....
 and toxic strong acid
Strong acid

A strong acid is an acid that ionizes completely in an aqueous solution , or in other terms, with a acid dissociation constant < -1.74. This generally means that in aqueous solution at standard temperature and pressure, the concentration of hydronium ions is equal to the concentration of strong acid introduced to the solution....
 that can cause severe burns.

Colorless when pure, older samples tend to acquire a yellow cast due to the accumulation of oxides of nitrogen
Nitrogen oxide

The term nitrogen oxide typically refers to any binary compound of oxygen and nitrogen, or to a mixture of such compounds:* Nitric oxide , nitrogen oxide...
. If the solution contains more than 86% nitric acid, it is referred to as fuming nitric acid. Fuming nitric acid is characterized as white fuming nitric acid
White fuming nitric acid

White fuming nitric acid is a storable liquid oxidizer used with kerosene and hydrazine rocket fuel. It consists of nearly pure nitric acid . WFNA is commonly specified as containing no more than 2% water and less than 0.5% solution nitrogen dioxide or dinitrogen tetroxide....
 and red fuming nitric acid
Red fuming nitric acid

Red fuming nitric acid is a storable oxidizer used as a rocket propellant. It consists mainly of nitric acid , also containing 13% dinitrogen tetroxide and 3% water....
, depending on the amount of nitrogen dioxide
Nitrogen dioxide

Nitrogen dioxide is the chemical compound with the chemical formula NitrogenOxygen2. One of several nitrogen oxides, NO2 is an intermediate in the industrial synthesis of nitric acid, millions of tons of which are produced each year....
 present.

Properties

Pure anhydrous nitric acid (100%) is a colorless liquid with a density of 1522 kg/m³ which solidifies at -42 °C to form white crystals and boils at 83 °C. When boiling in light, even at room temperature, there is a partial decomposition
Decomposition

Decomposition refers to the process by which tissues of dead organisms break down into simpler forms of matter. Such a breakdown of dead organisms is essential for new growth and development of living organisms because it recycles the finite chemical constituents and frees up the limited physical space in the biome....
 with the formation of nitrogen dioxide following the reaction:

4HNO3 ? 2H2O + 4NO2 + O2 (72°C)


which means that anhydrous nitric acid should be stored below 0 °C to avoid decomposition. The nitrogen dioxide
Nitrogen dioxide

Nitrogen dioxide is the chemical compound with the chemical formula NitrogenOxygen2. One of several nitrogen oxides, NO2 is an intermediate in the industrial synthesis of nitric acid, millions of tons of which are produced each year....
 (NO2) remains dissolved in the nitric acid coloring it yellow, or red at higher temperatures. While the pure acid tends to give off white fumes when exposed to air, acid with dissolved nitrogen dioxide gives off reddish-brown vapours, leading to the common name "red fuming acid" or "fuming nitric acid". Fuming nitric acid is also referred to as 16-molar nitric acid –– as the most concentrated form of nitric acid at Standard Temperature and Pressure
Standard conditions for temperature and pressure

In physical sciences, standard conditions for temperature and pressure are standard sets of conditions for experimental measurements, to allow comparisons to be made between different sets of data....
 (STP).

Nitric acid is miscible with water and distillation
Distillation

Distillation is a method of separation process mixtures based on differences in their Volatility in a boiling liquid mixture. Distillation is a unit operation, or a physical separation process, and not a chemical reaction....
 gives an azeotrope
Azeotrope

An azeotrope is a mixture of two or more liquids in such a ratio that its composition cannot be changed by simple distillation. This occurs because, when an azeotrope is boiled, the resulting vapor has the same ratio of constituents as the original mixture....
 with a concentration of 68% HNO3 and a boiling temperature of 120.5 °C at 1 atm, which is the ordinary concentrated nitric acid of commerce. Two solid hydrates are known; the monohydrate (HNO3·H2O) and the trihydrate (HNO3·3H2O).

Nitrogen oxide
Nitrogen oxide

The term nitrogen oxide typically refers to any binary compound of oxygen and nitrogen, or to a mixture of such compounds:* Nitric oxide , nitrogen oxide...
s (NOx) are soluble in nitric acid and this property influences more or less all the physical characteristics depending on the concentration of the oxides. These mainly include the vapor pressure above the liquid and the boiling temperature, as well as the color mentioned above.

Nitric acid is subject to thermal
Thermal

A thermal column is a column of rising air in the lower altitudes of the Earth's atmosphere. Thermals are created by the uneven heating of the Earth's surface from solar radiation, and an example of convection....
 or light decomposition with increasing concentration
Concentration

In chemistry, concentration is the measure of how much of a given chemical substance there is mixed with another substance. This can apply to any sort of chemical mixture, but most frequently the concept is limited to homogeneous solutions, where it refers to the amount of solute in the solvent....
 and this may give rise to some non-negligible variations in the vapour pressure above the liquid because the nitrogen oxides produced dissolve partly or completely in the acid.

Acidic properties

Being a typical acid, nitric acid reacts with alkali
Alkali

In chemistry, an alkali is a Base , Ionic compound salt of an alkali metal or alkaline earth metal Chemical element. Alkalis are best known for being Base s that dissolve in water....
s, basic oxide
Basic oxide

In chemistry, a basic oxide is an oxide that either*reacts with water to form a base.*reacts with an acid to form a salt.Examples include:...
s, and carbonate
Carbonate

In chemistry, a carbonate is a salt or ester of carbonic acid....
s to form salts, such as ammonium nitrate
Ammonium nitrate

The chemical compound ammonium nitrate, the nitrate of ammonia with the chemical formula NitrogenHydrogen4NitrogenOxygen3, is a white powder at room temperature and standard pressure....
. Due to its oxidizing nature, nitric acid generally does not donate its proton (that is, it does not liberate hydrogen
Hydrogen

Hydrogen is the chemical element with atomic number 1. It is represented by the chemical symbol H. At standard temperature and pressure, hydrogen is a colorless, odorless, nonmetallic, tasteless, highly combustion and explosive Diatomic molecule gas with the molecular formula H2....
) on reaction with metal
Metal

In chemistry, a metal is a chemical element whose atoms readily lose electrons to form positive ions , and form metallic bonds between other metal atoms and ionic bonds between nonmetal atoms....
s and the resulting salts are usually in the higher oxidized states. For this reason, heavy corrosion
Corrosion

Corrosion means the breaking down of essential properties in a material due to chemical reactions with its surroundings. In the most common use of the word, this means a loss of electrons of metals reacting with water and oxygen....
 can be expected and should be guarded against by the appropriate use of corrosion resistant metals or alloy
Alloy

An alloy is a partial or complete solid solution of one or more chemical element in a metallic matrix. Complete solid solution alloys give single solid phase microstructure, while partial solutions give two or more phases that may be homogeneous in distribution depending on thermal history....
s.

Nitric acid has an acid dissociation constant
Acid dissociation constant

An acid dissociation constant, Ka, is a quantitative measure of the strong acid in solution. It is the equilibrium constant for a chemical reaction known as Dissociation in the context of acid-base reactions....
 (pKa) of -1.4: in aqueous
Water

Water is a common chemical substance that is essential for the survival of all known forms of life. In typical usage, water refers only to its liquid form or States of matter, but the substance also has a solid state, ice, and a gaseous state, water vapor or steam....
 solution
Solution

In chemistry, a solution is a homogeneous mixture composed of two or more substances. In such a mixture, a solute is dissolved in another substance, known as a solvent....
, it almost completely (93% at 0.1 mol/L) ionizes into the nitrate
Nitrate

In inorganic chemistry, a nitrate is a salt of nitric acid with an ion composed of one nitrogen and three oxygen atoms . In organic chemistry the esters of nitric acid and various alcohols are called nitrates....
 ion
Ion

An ion is an atom or molecule which has lost or gained one or more electrons, giving it a positive or negative electrical charge. According to the Bohr_model this will be from or in the outer shield 'n'....
 NO3- and a hydrated proton
Proton

The proton is a subatomic particle with an electric charge of +1 elementary charge. It is found in the nucleus of each atom but is also stable by itself and has a second identity as the hydrogen ion, H+....
, known as a hydronium
Hydronium

In chemistry, hydronium is the common name for the aqueous cation hydrogen3oxygen+ derived from protonation of water. It is the simplest type of an oxonium ion....
 ion, H3O+.

HNO3 + H2O ? H3O+ + NO3-


Oxidizing properties


Reactions with metals

Being a powerful oxidizing agent, nitric acid reacts violently with many organic materials and the reactions may be explosive. Depending on the acid concentration, temperature and the reducing agent involved, the end products can be variable. Reaction then takes place with all metals except the precious metal
Precious metal

A precious metal is a rare metallic chemical element of high economics value. Chemically, the precious metals are less reactivity than most elements, have high lustre , are softer or more ductility, and have higher melting points than other metals....
 series and certain alloys. This characteristic has made it a common agent to be used in acid tests
Acid test (gold)

An acid test for gold was used during the California Gold Rush of the 1850s by gold seekers and gold traders to quickly and incontestably find whether a given metal, excavated or found, was gold or a mere base metal....
. As a general rule, oxidizing reactions occur primarily with the concentrated acid, favouring the formation of nitrogen dioxide
Nitrogen dioxide

Nitrogen dioxide is the chemical compound with the chemical formula NitrogenOxygen2. One of several nitrogen oxides, NO2 is an intermediate in the industrial synthesis of nitric acid, millions of tons of which are produced each year....
 (NO2).

Cu + 4H+ + 2NO3- ? Cu2+ + 2NO2 + 2H2O


The acidic properties tend to dominate with dilute acid, coupled with the preferential formation of nitrogen oxide
Nitrogen oxide

The term nitrogen oxide typically refers to any binary compound of oxygen and nitrogen, or to a mixture of such compounds:* Nitric oxide , nitrogen oxide...
 (NO).

3Cu + 8HNO3 ? 3Cu(NO3)2 + 2NO + 4H2O


Since nitric acid is an oxidizing agent, hydrogen
Hydrogen

Hydrogen is the chemical element with atomic number 1. It is represented by the chemical symbol H. At standard temperature and pressure, hydrogen is a colorless, odorless, nonmetallic, tasteless, highly combustion and explosive Diatomic molecule gas with the molecular formula H2....
 (H2) is rarely formed. Only magnesium
Magnesium

Magnesium is a chemical element with the symbol Mg, atomic number 12, atomic weight 24.3050 and common oxidation number +2.Magnesium, an alkaline earth metal, is the ninth most abundance of the chemical elements in the universe by mass....
 (Mg), Manganese (Mn) and calcium
Calcium

Calcium is the chemical element with the symbol Ca and atomic number 20. It has an atomic mass of 40.078 amu. Calcium is a soft grey alkaline earth metal, and is the fifth most abundant element by mass in the earth's Crust ....
 (Ca) react with cold, dilute nitric acid to give hydrogen:

Mg(s) + 2HNO3 (aq) ? Mg(NO3)2 (aq) + H2 (g)


Nitric acid has the highest distinction (amongst all acids) of attacking and dissolving all metals on the periodic table except Gold
Gold

Gold is a chemical element with the symbol Au and atomic number 79. It is a highly sought-after precious metal, having been used as money, as a store of value, in jewelry, in sculpture, and for ornamentation since the beginning of recorded history....
 and Platinum
Platinum

Platinum is a chemical element with the chemical symbol Pt and an atomic number of 78. Its name is derived from the Spanish term platina del Pinto, which is literally translated into "little silver of the Pinto River." It is in Group 10 of the periodic table of elements....
.

Passivation
Although chromium
Chromium

Chromium is a chemical element which has the symbol Cr and atomic number 24. It is a steely-gray, Lustre , hard metal that takes a high polish and has a high melting point....
 (Cr), iron
Iron

Iron is a chemical element with the symbol Fe and atomic number 26. Iron is a Group 8 element and period 4 element. Iron is lustrous and silvery in color....
 (Fe) and aluminium
Aluminium

Aluminium or aluminum is a silvery white and ductile member of the boron group of chemical elements. It has the symbol Al; its atomic number is 13....
 (Al) readily dissolve in dilute nitric acid, the concentrated acid forms a metal oxide layer that protects the metal from further oxidation, which is called passivation
Passivation

Passivation is the process of making a material "passive" in relation to another material prior to using the materials together. For example, prior to storing hydrogen peroxide in an aluminium container, the container can be passivated by rinsing it with a dilute solution of nitric acid and peroxide alternating with deionized water....
. Typical passivation concentrations range from 18% to 22% by weight.

Reactions with non-metals
Reaction with non-metallic elements, with the exception of silicon
Silicon

Silicon is the most common metalloid. It is a chemical element, which has the symbol Si and atomic number 14. The atomic mass is 28.0855....
 and halogens, usually oxidizes them to their highest oxidation state
Oxidation number

The oxidation number of a central atom in a complex is the charge that it would have if all the ligands were removed along with the electron pairs that were shared with the central atom....
s as acids with the formation of nitrogen dioxide
Nitrogen dioxide

Nitrogen dioxide is the chemical compound with the chemical formula NitrogenOxygen2. One of several nitrogen oxides, NO2 is an intermediate in the industrial synthesis of nitric acid, millions of tons of which are produced each year....
 for concentrated acid and nitric oxide
Nitric oxide

Nitric oxide or nitrogen monoxide is a chemical compound with chemical formula NitrogenOxygen. This gas is an important signaling molecule in the body of mammals, including humans, and is an extremely important intermediate in the chemical industry....
 for dilute acid.

C + 4HNO3 ? CO2 + 4NO2 + 2H2O


or

3C + 4HNO3 ? 3CO2 + 4NO + 2H2O


Grades

White fuming nitric acid, also called 100% nitric acid or WFNA, is very close to the anhydrous nitric acid product. One specification for white fuming nitric acid is that it has a maximum of 2% water and a maximum of 0.5% dissolved NO2.

Red fuming nitric acid, or RFNA, contains substantial quantities of dissolved nitrogen dioxide (NO2) leaving the solution with a reddish-brown color. One formulation of RFNA specifies a minimum of 17% NO2, another specifies 13% NO2.

An inhibited fuming nitric acid (either IWFNA, or IRFNA) can be made by the addition of 0.6 to 0.7% hydrogen fluoride
Hydrofluoric acid

Hydrofluoric acid is a solution of hydrogen fluoride in water. While it is extremely corrosive and dangerous to handle, it is technically a weak acid....
, HF. This fluoride is added for corrosion resistance in metal tanks (the fluoride creates a metal fluoride layer that protects the metal).

Industrial production

Nitric acid is made by reacting nitrogen dioxide
Nitrogen dioxide

Nitrogen dioxide is the chemical compound with the chemical formula NitrogenOxygen2. One of several nitrogen oxides, NO2 is an intermediate in the industrial synthesis of nitric acid, millions of tons of which are produced each year....
 (NO2) with water
Water

Water is a common chemical substance that is essential for the survival of all known forms of life. In typical usage, water refers only to its liquid form or States of matter, but the substance also has a solid state, ice, and a gaseous state, water vapor or steam....
.

3 NO2 + H2O ? 2 HNO3 + NO


Normally, the nitric oxide
Nitric oxide

Nitric oxide or nitrogen monoxide is a chemical compound with chemical formula NitrogenOxygen. This gas is an important signaling molecule in the body of mammals, including humans, and is an extremely important intermediate in the chemical industry....
 produced by the reaction is reoxidized by the oxygen in air to produce additional nitrogen dioxide
Nitrogen dioxide

Nitrogen dioxide is the chemical compound with the chemical formula NitrogenOxygen2. One of several nitrogen oxides, NO2 is an intermediate in the industrial synthesis of nitric acid, millions of tons of which are produced each year....
.

Dilute nitric acid may be concentrated by distillation up to 68% acid, which is a maximum boiling azeotrope
Azeotrope

An azeotrope is a mixture of two or more liquids in such a ratio that its composition cannot be changed by simple distillation. This occurs because, when an azeotrope is boiled, the resulting vapor has the same ratio of constituents as the original mixture....
 containing 32% water. In the laboratory, further concentration involves distillation with sulphuric acid which acts as a dehydrating agent. Such distillations must be done with all-glass apparatus at reduced pressure, to prevent decomposition of the acid. Industrially, strong nitric acid is produced by dissolving additional nitrogen dioxide in 68% nitric acid in an absorption tower. Dissolved nitrogen oxides are either stripped in the case of white fuming nitric acid, or remain in solution to form red fuming nitric acid.

Commercial grade nitric acid solutions are usually between 52% and 68% nitric acid. Production of nitric acid is via the Ostwald process
Ostwald process

The Ostwald process is a chemistry process for producing nitric acid, which was developed by Wilhelm Ostwald . It is a mainstay of the modern chemical industry....
, named after German chemist Wilhelm Ostwald
Wilhelm Ostwald

Friedrich Wilhelm Ostwald was a Baltic German chemist. He received the Nobel Prize in Chemistry in 1909 for his work on catalysis, chemical equilibria and reaction velocities....
. In this process, anhydrous ammonia
Ammonia

Ammonia is a chemical compound with the chemical formula nitrogenhydrogen. It is normally encountered as a gas with a characteristic pungent odor....
 is oxidized to nitric oxide
Nitric oxide

Nitric oxide or nitrogen monoxide is a chemical compound with chemical formula NitrogenOxygen. This gas is an important signaling molecule in the body of mammals, including humans, and is an extremely important intermediate in the chemical industry....
, which is then reacted with oxygen in air to form nitrogen dioxide
Nitrogen dioxide

Nitrogen dioxide is the chemical compound with the chemical formula NitrogenOxygen2. One of several nitrogen oxides, NO2 is an intermediate in the industrial synthesis of nitric acid, millions of tons of which are produced each year....
. This is subsequently absorbed in water to form nitric acid and nitric oxide. The nitric oxide is cycled back for reoxidation. By using ammonia derived from the Haber process
Haber process

The Haber process, also called the Haber?Bosch process, is the nitrogen fixation reaction of nitrogen and hydrogen, over an enriched iron Catalysis, to produce ammonia....
, the final product can be produced from nitrogen, hydrogen, and oxygen which are derived from air and natural gas as the sole feedstocks.

Laboratory synthesis

In laboratory, nitric acid can be made from copper(II) nitrate
Copper(II) nitrate

Copper nitrate is the chemical compound with the formula Copper2. Commonly referred to simply as copper nitrate, the anhydrous form is a blue, crystalline solid....
 or by reacting approximately equal masses of potassium nitrate
Potassium nitrate

Potassium nitrate is a chemical compound with the chemical formula PotassiumNitrogenOxygen3. A naturally occurring mineral source of nitrogen, KNO3 constitutes a critical oxidation component of black powder/gunpowder....
 (KNO3) with 96% sulfuric acid
Sulfuric acid

Sulfuric acid, hydrogen2sulfuroxygen4, is a strong mineral acid. It is soluble in water at all concentrations. Sulfuric acid has many applications, and is one of the top products of the chemical industry....
 (H2SO4), and distilling this mixture at nitric acid's boiling point of 83 °C until only a white crystalline mass, potassium hydrogen sulfate
Potassium hydrogen sulfate

Potassium bisulfate is the potassium salt of bisulfate anion, with the molecular formula KHSO4. This compound is commonly used in the conversion of tartrates to bitartrates in wine....
 (KHSO4), remains in the reaction vessel. The obtained red fuming nitric acid may be converted to the white nitric acid.

H2SO4 + KNO3 ? KHSO4 + HNO3


The dissolved NOx
Nox

Nox may refer to:* Nox , the primordial goddess of the night in Greek mythology* Nox , a race in the television series Stargate SG-1* Nox , a video game developed by Westwood Studios...
 are readily removed using reduced pressure at room temperature (10-30 min at 200 mmHg
Torr

The torr is a non-International System of Units unit of pressure defined as 1/760 of an Atmosphere . It was named after Evangelista Torricelli, an Italian physicist and mathematician who discovered the principle of the barometer in 1644....
 or 27 kPa) to give white fuming nitric acid. This procedure can also be performed under reduced pressure and temperature in one step in order to produce less nitrogen dioxide
Nitrogen dioxide

Nitrogen dioxide is the chemical compound with the chemical formula NitrogenOxygen2. One of several nitrogen oxides, NO2 is an intermediate in the industrial synthesis of nitric acid, millions of tons of which are produced each year....
 gas.

Uses

IWFNA may be used as the oxidizer in liquid fuel rockets. IRFNA was one of 3 liquid fuel components for the BOMARC missile

A solution of nitric acid and alcohol, Nital
Nital

Nital is a solution of alcohol and nitric acid commonly used for routine industrial etching of metals. It is especially suitable for revealing the microstructure of steels....
, is used for etching of metals to reveal the microstructure.

Commercially available aqueous blends of 5-30% nitric acid and 15-40% phosphoric acid are commonly used for cleaning food and dairy equipment primarily to remove precipitated calcium and magnesium compounds (either deposited from the process stream or resulting from the use of hard water during production and cleaning).

Nitric acid is also used in explosives, and is key to the manufacture of Nitroglycerin
Nitroglycerin

Nitroglycerin , also known as nitroglycerine, , trinitroglycerin, trinitroglycerine, 1,2,3-trinitroxypropane and glyceryl trinitrate, is a heavy, colorless, oily, explosive liquid obtained by nitration glycerol....
 and RDX
RDX

Cyclotrimethylenetrinitramine, also known as RDX, cyclonite, hexogen, and T4, is an explosive nitroamine widely used in military and industrial applications....
.

Clog remover

In a high medium concentration nitric acid is used as a cheap clog remover.

Digestion

In elemental analysis
Elemental analysis

Elemental analysis is a process where a sample of some material is analyzed for its chemical element and sometimes isotope composition. Elemental analysis can be qualitative , and it can be quantitative ....
 by ICP-MS
ICP-MS

ICP-MS is a type of mass spectrometry that is highly sensitive and capable of the determination of a range of metals and several non-metals at concentrations below one part in 1012....
, ICP-AES
ICP-AES

Inductively coupled plasma atomic emission spectroscopy , also referred to as inductively coupled plasma optical emission spectrometry , is an analytical technique used for the detection of trace metals....
, GFAA, and Flame AA, dilute nitric acid (0.5 to 5.0 %) is used as a matrix compound for determining metal traces in solutions. Ultrapure acid is required for such determination, because small amounts of metal ions could affect the result of the analysis.

Woodworking

In a low concentration (approximately 10%), nitric acid is often used to artificially age pine
Pine

Pines are Pinophyta trees in the genus Pinus, in the family Pinaceae. They make up the monotypic subfamily Pinoideae. There are about 115 species of pine, although different authorities accept between 105 and 125 species....
 and maple
Maple

Acer is a genus of trees or shrubs commonly known as Maple. Maples are variously classified in a family of their own, the Aceraceae, or included in the family Sapindaceae....
. The color produced is a grey-gold very much like very old wax or oil finished wood (wood finishing
Wood finishing

Wood finishing refers to the process of embellishing and/or protecting the surface of a wooden material. The process starts with surface preparation, either by sandpaper by hand , Card scraper, or Plane ....
).

Other uses


Alone, it is useful in metallurgy
Metallurgy

Metallurgy is a domain of materials science that studies the physical and chemical behavior of metallic Chemical element, their intermetallics, and their mixtures, which are called alloys....
 and refining
Refining

Refining is the process of purification of a chemical compound. The term is usually used of a natural resource that is almost in a usable form, but which is more useful in its pure form....
 as it reacts with most metal
Metal

In chemistry, a metal is a chemical element whose atoms readily lose electrons to form positive ions , and form metallic bonds between other metal atoms and ionic bonds between nonmetal atoms....
s, and in organic syntheses
Chemical synthesis

In chemistry, chemical synthesis is purposeful execution of chemical reactions in order to get a product , or several products. This happens by physics and chemical manipulations usually involving one or more reactions....
. When mixed with hydrochloric acid
Hydrochloric acid

Hydrochloric acid is the solution of hydrogen chloride in water. It is a highly corrosive, strong acid mineral acid and has major industrial uses....
, nitric acid forms Aqua Regia
Aqua regia

Aqua regia is a highly corrosive, fuming yellow or red solution. The mixture is formed by freshly mixing concentrated nitric acid and concentrated hydrochloric acid, usually in a volumetric ratio of 1:3 respectively....
, one of the few reagent
Reagent

A reagent or reactant is a substance or compound consumed during a chemical reaction. Solvents and catalysts, although they are involved in the reaction, are usually not referred to as reactants....
s capable of dissolving gold
Gold

Gold is a chemical element with the symbol Au and atomic number 79. It is a highly sought-after precious metal, having been used as money, as a store of value, in jewelry, in sculpture, and for ornamentation since the beginning of recorded history....
 and platinum
Platinum

Platinum is a chemical element with the chemical symbol Pt and an atomic number of 78. Its name is derived from the Spanish term platina del Pinto, which is literally translated into "little silver of the Pinto River." It is in Group 10 of the periodic table of elements....
. The reason for Aqua Regia
Aqua regia

Aqua regia is a highly corrosive, fuming yellow or red solution. The mixture is formed by freshly mixing concentrated nitric acid and concentrated hydrochloric acid, usually in a volumetric ratio of 1:3 respectively....
 to be so active is the formation of free chlorine radicals in the statu nascendi when the two acids are mixed.

Safety

Nitric acid is a powerful oxidizing agent
Oxidizing agent

An oxidizing agent can be defined as either:#a chemical compound that readily transfers oxygen atoms, or#a substance that gains electrons in a redox chemical reaction...
, and the reactions of nitric acid with compounds such as cyanide
Cyanide

A cyanide is any chemical compound that contains the nitrile , which consists of a carbon atom chemical bond to a nitrogen atom. Inorganic cyanides are hydrogen cyanide salts in which cyanide is generally the anion CN-....
s, carbide
Carbide

In chemistry, a carbide is a compound composed of carbon and a less electronegativity element. Carbides can be generally classified by chemical bonding type as follows: salt-like, covalent compounds, interstitial compounds, and "intermediate" transition metal carbides....
s, and metallic powders can be explosive. Reactions of nitric acid with many organic compounds, such as turpentine
Turpentine

Turpentine is a fluid obtained by the distillation of resin obtained from trees, mainly pine trees. It is composed of terpenes, mainly the monoterpenes alpha-Pinene and beta-Pinene....
, are violent and hypergolic (i.e., self-igniting).

Concentrated nitric acid dyes human skin
Skin

The skin is the outer covering of the body, also known as the epidermis. It is the largest organ of the integumentary system made up of multiple layers of epithelial biological tissue, and guards the underlying muscles, bones, ligaments and organ s....
 yellow due to a reaction with the keratin
Keratin

Keratins are a family of fibrous protein; tough and insoluble, they form the hard but mineral structures found in reptiles, birds, amphibians and mammals....
. These yellow stains turn orange when neutralized.

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