Chloric acid
Encyclopedia
Chloric acid, H
Cl
O
3, is an oxoacid
of chlorine
, and the formal precursor of chlorate
salts. It is a strong acid
(pKa
≈ −1) and oxidizing agent
.
It is prepared by the reaction of sulfuric acid
with barium chlorate
, the insoluble barium sulfate
being removed by precipitation:
Another method is the heating of hypochlorous acid
, of which productions include chloric acid and hydrogen chloride
:
It is also produced by the reaction of sulfuric acid with potassium chlorate in the combustion of sugar using potassium chlorate, sulfuric acid, and sugar.
It is stable in cold aqueous solution up to a concentration of approximately 30%, and solution of up to 40% can be prepared by careful evaporation under reduced pressure. Above these concentrations, and on warming, chloric acid solutions decompose to give a variety of products, for example:
The decomposition is controlled by kinetic factors: indeed, chloric acid is never thermodynamically stable with respect to disproportionation
.
Chloric acid is a dangerously powerful oxidizing agent and will cause most organics and flammables to deflagrate on contact. For example a mixture of potassium chlorate
and sugar
will burn when concentrated sulfuric acid
is added due to chloric acid production. Because sulfur tends to contain acidic impurities, it will form highly unstable mixtures with potassium chlorate
due to chloric acid being produced.
Chloric Acid produced from the addition of concentrated sulfuric acid
can decompose explosively producing a variety of products such as oxygen
, chlorine
, and chlorine oxides
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...
Cl
Chlorine
Chlorine is the chemical element with atomic number 17 and symbol Cl. It is the second lightest halogen, found in the periodic table in group 17. The element forms diatomic molecules under standard conditions, called dichlorine...
O
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
3, is an oxoacid
Oxoacid
An oxoacid is an acid that contains oxygen. To be more specific, it is an acid that:#contains oxygen#contains at least one other element#has at least one hydrogen atom bound to oxygen#forms an ion by the loss of one or more protons....
of chlorine
Chlorine
Chlorine is the chemical element with atomic number 17 and symbol Cl. It is the second lightest halogen, found in the periodic table in group 17. The element forms diatomic molecules under standard conditions, called dichlorine...
, and the formal precursor of chlorate
Chlorate
The chlorate anion has the formula ClO. In this case, the chlorine atom is in the +5 oxidation state. "Chlorate" can also refer to chemical compounds containing this anion; chlorates are the salts of chloric acid. "Chlorate", when followed by a roman numeral in parentheses, e.g...
salts. It is a strong acid
Strong acid
A strong acid is an acid that ionizes completely in an aqueous solution by losing one proton, according to the equationFor sulfuric acid which is diprotic, the "strong acid" designation refers only to dissociation of the first protonMore precisely, the acid must be stronger in aqueous solution than...
(pKa
Acid dissociation constant
An acid dissociation constant, Ka, is a quantitative measure of the strength of an acid in solution. It is the equilibrium constant for a chemical reaction known as dissociation in the context of acid-base reactions...
≈ −1) and oxidizing agent
Oxidizing agent
An oxidizing agent can be defined as a substance that removes electrons from another reactant in a redox chemical reaction...
.
It is prepared by the reaction of sulfuric acid
Sulfuric acid
Sulfuric acid is a strong mineral acid with the molecular formula . Its historical name is oil of vitriol. Pure sulfuric acid is a highly corrosive, colorless, viscous liquid. The salts of sulfuric acid are called sulfates...
with barium chlorate
Barium chlorate
Barium chlorate is a white crystalline solid. It is an irritant, as are all barium compounds. If consumed, barium chlorate can cause nausea, vomiting, and diarrhea. It is used in pyrotechnics to produce a green color...
, the insoluble barium sulfate
Barium sulfate
Barium sulfate is the inorganic compound with the chemical formula BaSO4. It is a white crystalline solid that is odorless and insoluble in water. It occurs as the mineral barite, which is the main commercial source of barium and materials prepared from it...
being removed by precipitation:
- Ba(ClO3)2 + H2SO4 → 2HClO3 + BaSO4
Another method is the heating of hypochlorous acid
Hypochlorous acid
Hypochlorous acid is a weak acid with the chemical formula HClO. It forms when chlorine dissolves in water. It cannot be isolated in pure form due to rapid equilibration with its precursor...
, of which productions include chloric acid and hydrogen chloride
Hydrogen chloride
The compound hydrogen chloride has the formula HCl. At room temperature, it is a colorless gas, which forms white fumes of hydrochloric acid upon contact with atmospheric humidity. Hydrogen chloride gas and hydrochloric acid are important in technology and industry...
:
- 3HClO → HClO3 + 2 HCl
It is also produced by the reaction of sulfuric acid with potassium chlorate in the combustion of sugar using potassium chlorate, sulfuric acid, and sugar.
It is stable in cold aqueous solution up to a concentration of approximately 30%, and solution of up to 40% can be prepared by careful evaporation under reduced pressure. Above these concentrations, and on warming, chloric acid solutions decompose to give a variety of products, for example:
- 8HClO3 → 4HClO4 + 2H2O + 2Cl2 + 3 O2
- 3HClO3 → HClO4 + H2O + 2 ClO2
The decomposition is controlled by kinetic factors: indeed, chloric acid is never thermodynamically stable with respect to disproportionation
Disproportionation
Disproportionation, also known as dismutation is used to describe a specific type of redox reaction in which a species is simultaneously reduced and oxidized so as to form two different products....
.
Chloric acid is a dangerously powerful oxidizing agent and will cause most organics and flammables to deflagrate on contact. For example a mixture of potassium chlorate
Potassium chlorate
Potassium chlorate is a compound containing potassium, chlorine and oxygen atoms, with the molecular formula KClO3. In its pure form, it is a white crystalline substance. It is the most common chlorate in industrial use...
and sugar
Sugar
Sugar is a class of edible crystalline carbohydrates, mainly sucrose, lactose, and fructose, characterized by a sweet flavor.Sucrose in its refined form primarily comes from sugar cane and sugar beet...
will burn when concentrated sulfuric acid
Sulfuric acid
Sulfuric acid is a strong mineral acid with the molecular formula . Its historical name is oil of vitriol. Pure sulfuric acid is a highly corrosive, colorless, viscous liquid. The salts of sulfuric acid are called sulfates...
is added due to chloric acid production. Because sulfur tends to contain acidic impurities, it will form highly unstable mixtures with potassium chlorate
Potassium chlorate
Potassium chlorate is a compound containing potassium, chlorine and oxygen atoms, with the molecular formula KClO3. In its pure form, it is a white crystalline substance. It is the most common chlorate in industrial use...
due to chloric acid being produced.
Chloric Acid produced from the addition of concentrated sulfuric acid
Sulfuric acid
Sulfuric acid is a strong mineral acid with the molecular formula . Its historical name is oil of vitriol. Pure sulfuric acid is a highly corrosive, colorless, viscous liquid. The salts of sulfuric acid are called sulfates...
can decompose explosively producing a variety of products such as oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
, chlorine
Chlorine
Chlorine is the chemical element with atomic number 17 and symbol Cl. It is the second lightest halogen, found in the periodic table in group 17. The element forms diatomic molecules under standard conditions, called dichlorine...
, and chlorine oxides
See also
- Hypochlorous acidHypochlorous acidHypochlorous acid is a weak acid with the chemical formula HClO. It forms when chlorine dissolves in water. It cannot be isolated in pure form due to rapid equilibration with its precursor...
- Chlorous acidChlorous acidChlorous acid is an inorganic compound with the formula HClO2. It is a weak acid. Chlorine has oxidation state +3 in this acid. The pure substance is unstable, disproportionating to hypochlorous acid and chloric acid :Although the acid is difficult to obtain in pure substance, the conjugate base,...
- Perchloric acidPerchloric acidPerchloric acid is the inorganic compound with the formula HClO4. Usually encountered as an aqueous solution, this colourless compound is a strong acid comparable in strength to sulfuric and nitric acids. It is a powerful oxidizer, but its aqueous solutions up to appr. 70% are remarkably inert,...
- Bromic acidBromic acidBromic acid, also known as hydrogen bromate, is an oxoacid that only exists in aqueous solution. It is a colorless solution that turns yellow at room temperature as it decomposes to bromine. Bromic acid and bromates are powerful oxidizing agents and are common ingredients in Belousov-Zhabotinsky...
- Iodic acidIodic acidIodic acid, HIO3, can be obtained as a white solid. It dissolves in water very well, but it also exists in the pure state, as opposed to chloric acid or bromic acid. Iodic acid contains iodine in the oxidation state +5 and it is one of the most stable oxo-acids of the halogens in its pure state....
- Oxidizing acidOxidizing acidAn oxidizing acid is a Brønsted acid that is also a strong oxidizing agent . All Brønsted acids can act as moderately strong oxidizing agents, because the acidic proton can be reduced to hydrogen gas. Some acids contain other structures that act as stronger oxidizing agents than hydrogen....
- ChlorateChlorateThe chlorate anion has the formula ClO. In this case, the chlorine atom is in the +5 oxidation state. "Chlorate" can also refer to chemical compounds containing this anion; chlorates are the salts of chloric acid. "Chlorate", when followed by a roman numeral in parentheses, e.g...