Perchloric acid

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Perchloric acid

Perchloric acid, HClO₄, is an oxoacid

Oxoacid

An oxoacid is an acid which contains oxygen. More specifically, it is an acid which:#contains oxygen;#contains at least one other Chemical element;...
of chlorine

Chlorine

Chlorine...
and is a colorless liquid soluble in water

Water (molecule)

File:Blue-water-pool.jpgWater is the most abundant molecule on Earth's surface, constituting about 70% of the Earth's surface in liquid, solid, and gaseous states....
. It is a 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....
comparable in strength to sulfuric

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....
and nitric acid

Nitric acid

Nitric acid , also known as aqua fortis and spirit of nitre, is a highly corrosion and toxic strong acid that can cause severe burns....
s. It is useful for preparing perchlorate salts, but it is also dangerously corrosive and readily forms explosive mixtures.

hloric acid is produced by treatment of sodium perchlorate

Sodium perchlorate

Sodium perchlorate is a perchlorate of sodium and has the formula NaClO4. Sodium perchlorate melts with decomposition at 480 ?C. Its heat of formation is -382.75 kJ mol-1....
with sulfuric acid

Sulfuric acid

Superacid

A superacid is an acid with an acidity greater than that of 100% sulfuric acid, which has a Hammett acidity function of -12. Commercially available superacids include trifluoromethanesulfonic acid , also known as triflic acid, and fluorosulfuric acid , both of which are about a thousand times stronger than sulfuric acid....
, and one of the strongest Brønsted-Lowry acids.

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Encyclopedia

Perchloric acid, HClO₄, is an oxoacid

Oxoacid

An oxoacid is an acid which contains oxygen. More specifically, it is an acid which:#contains oxygen;#contains at least one other Chemical element;...
of chlorine

Chlorine

Chlorine...
and is a colorless liquid soluble in water

Water (molecule)

File:Blue-water-pool.jpgWater is the most abundant molecule on Earth's surface, constituting about 70% of the Earth's surface in liquid, solid, and gaseous states....
. It is a strong acid

Strong acid

Sulfuric acid

Nitric acid

Production

Perchloric acid is produced by treatment of sodium perchlorate

Sodium perchlorate

Sodium perchlorate is a perchlorate of sodium and has the formula NaClO4. Sodium perchlorate melts with decomposition at 480 ?C. Its heat of formation is -382.75 kJ mol-1....
with sulfuric acid

Sulfuric acid

Acidity

Perchloric acid is a superacid

Superacid

PKA

PKA or pKa may be:* Protein kinase A, a cAMP activated protein kinase* pKa, the symbol for Acid dissociation constant...
is -7.

Anhydrous perchloric acid is an oily liquid. It forms a series of at least five hydrates

Water of crystallization

Water of crystallization is water that occurs in crystals but is not covalent bond to a host molecule or ion. The term is archaic and predates modern structural inorganic chemistry, coming from an era when the relationships between stoichiometry and structure were poorly understood....
, several of which have been characterized crystallographically

X-ray crystallography

X-ray crystallography is a method of determining the arrangement of atoms within a crystal, in which a beam of X-rays strikes a crystal and scatters into many different directions....
. The dihydrate is representative: the solid consists of the perchlorate

Perchlorate

Perchlorates are the salt derived from perchloric acid . They occur both naturally and through manufacturing. They have been used as a medicine for more than 50 years to treat thyroid gland disorders....
anion linked to H₂O and H₃O⁺

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....
centers via hydrogen bond

Hydrogen bond

A hydrogen bond is the attractive force between one electronegative atom and a hydrogen covalently bonded to another electronegative atom. It results from a dipole-dipole force with a hydrogen atom bonded to nitrogen, oxygen or fluorine ....
s. Perchloric acid forms 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 water, consisting of about 72.5% perchloric acid. This form of the acid is stable indefinitely and is commercially available. Such solutions are hygroscopic

Hygroscopy

Hygroscopy is the ability of a substance to attract water molecules from the surrounding Natural environment through either absorption or adsorption....
, that is, if left unsealed, concentrated acid dilutes itself by absorbing water from the air.

A 0.100 molar solution in glacial acetic acid

Acetic acid

Acetic acid, CH3COOH, also known as ethanoic acid, is an organic acid which gives vinegar its sour taste and pungent smell. Pure, water-free acetic acid is a colourless liquid that absorbs water from the environment , and freezes at 16.7 Celsius to a colourless crystalline solid....
is used as an analytical reagent. Titration

Titration

Titration is a common laboratory method of quantitative Analytical chemistry that is used to determine the unknown concentration of a known reactant....
of weak bases

Base (chemistry)

In chemistry, a base is most commonly thought of as an aqueous substance that can accept protons. A base is also often referred to as an alkali if OH- ions are involved....
is made easier if the usual medium, water, is replaced by glacial acetic acid. Glacial acetic acid is a much weaker base than water, so the base being titrated appears to be stronger. As a counterpart, the strength of acids is reduced. This shows the difference in strength among the strong acids.

Laboratory preparation

The concentrated acid can be prepared by 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....
of a solution of sodium perchlorate

Perchlorate

NaClO₄ + H₂SO₄ ? NaHSO₄ + HClO₄

In a related method, barium perchlorate reacts with dilute sulfuric acid to precipitate barium sulfate

Barium sulfate

Barium sulfate is a white crystalline solid with the chemical formula BaSO4. It is Solubility in water and other traditional solvents but is soluble in concentrated sulfuric acid....
, leaving perchloric acid. It also can be made by mixing nitric acid

Nitric acid

Nitric acid , also known as aqua fortis and spirit of nitre, is a highly corrosion and toxic strong acid that can cause severe burns....
with ammonium perchlorate

Ammonium perchlorate

Ammonium perchlorate is a chemical compound with the formula NitrogenHydrogen4ChlorineOxygen4.It is the salt of ammonia and perchloric acid....
. The reaction gives nitrous oxide

Nitrous oxide

Nitrous oxide, commonly known as "laughing gas", is a chemical compound with the chemical formula Nitrogen2Oxygen. At room temperature, it is a colorless Flammability gas, with a pleasant, slightly sweet odor and taste....
and perchloric acid due to a concurrent reaction involving the ammonium ion.

Safety

Anhydrous and monohydrated perchloric acid are explosive, but the usual aqueous solutions are stable in the absence of organic compounds. It is very corrosive to skin and eyes. Upon contact with perchloric acid, organic materials such as cloth and wood ignite. Salts of perchloric acid are also powerful oxidizers that can be explosive. Perchlorate salts tend to be more stable than their chlorate

Chlorate

The chlorate anion has the formula ClO3-. In this case, the chlorine atom is in the +5 oxidation state. "Chlorate" can also refer to chemical compounds containing this anion; Chlorate#Compounds are the salt s of chloric acid....
counterparts, which has led to their increased use in pyrotechnic compositions due to safety concerns.

Perchloric acid

Production

Acidity

Laboratory preparation

Safety

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