H2SO4

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chembox| verifiedrevid = 477003658| ImageFile = Sulfuric-acid-2D-dimensions.svg| ImageAlt = S=O bond length = 142.2 pm,
S-O bond length = 157.4 pm,
O-H bond length = 97 pm| ImageFile1 = Sulfuric-acid-Givan-et-al-1999-3D-balls.png| ImageSize1 = 160| ImageFile3 = Sulphuric acid 96 percent extra pure.jpg| IUPACName = Sulfuric acid| OtherNames = Oil of vitriol| Section1 = | Section2 = | Section4 = | Section7 = | Section8 = Sulfuric acid ( Sulfur#Spelling and etymology|alternative spelling sulphuric acid ) is a highly corrosive strong acid|strong mineral acid with the molecular formula Hydrogen|H₂ sulfate|SO₄ . It is a colorless to slightly yellow viscous liquid which is soluble in water at all concentrations. Sometimes, it may be dark brown as dyed during industrial production process in order to alert people's awareness to its hazards. The historical name of this acid is oil of vitriol .

It is a diprotic acid which may show different properties depending upon its concentration. Its corrosiveness on metals , stones , skin , eyes and flesh or other materials can be mainly ascribed to its strong acid|strong acidic nature and if concentrated strong dehydration|dehydrating property and oxidizing agent|strong oxidizing property . Moreover, it is hygroscopic which readily absorbs water vapour in air .

Possessing different chemical properties, the sulfuric acid has a wide range of applications including drain cleaner|domestic acidic drain cleaner , electrolyte in lead-acid batteries and various cleaning agent s. It is also a central substance in the chemical industry . Principal uses include mineral processing , fertilizer manufacturing, Oil refinery|oil refining , wastewater processing , and chemical synthesis . It is widely produced with different methods,such as contact process , wet sulfuric acid process and some other methods.

History

The study of vitriol began in Classical antiquity|ancient times . Sumerians had a list of types of vitriol that they classified according to substance's color. Some of the earliest discussions on the origin and properties of vitriol are in the works of the Greek physician Dioscorides (first century AD) and the Roman naturalist Pliny the Elder (23–79 AD). Galen also discussed its medical use. Metallurgical uses for vitriolic substances were recorded in the Hellenistic alchemical works of Zosimos of Panopolis , in the treatise Phisica et Mystica , and the " Leyden papyrus X ".Vladimir Karpenko, John A. Norris (2001), , Charles University in Prague|Charles University

Alchemy and chemistry in medieval Islam|Islamic alchemists Jabir ibn Hayyan (c. 721 – c. 815 AD), Muhammad ibn Zakariya al-Razi|Razi (865 – 925 AD), and Jamal Din al-Watwat (d. 1318, wrote the book ''Mabahij al-fikar wa-manahij al-'ibar ), included vitriol in their mineral classification lists. Ibn Sina focused on its medical uses and different varieties of vitriol.

Sulfuric acid was called "oil of vitriol" by medieval European alchemists. There are references to it in the works of Vincent of Beauvais and in the Compositum de Compositis ascribed to Albertus Magnus . A passage from Pseudo-Geber ´s Summa Perfectionis was long considered to be the first recipe for sulfuric acid, but this was a misinterpretation.

In the 17th century, the German-Dutch chemist Johann Glauber prepared sulfuric acid by burning sulfur together with Potassium nitrate|saltpeter ( potassium nitrate , ), in the presence of steam. As saltpeter decomposes, it oxidizes the sulfur to , which combines with water to produce sulfuric acid. In 1736, Joshua Ward , a London pharmacist, used this method to begin the first large-scale production of sulfuric acid.

In 1746 in Birmingham, John Roebuck adapted this method to produce sulfuric acid in lead -lined chambers, which were stronger, less expensive, and could be made larger than the previously used glass containers. This lead chamber process allowed the effective industrialization of sulfuric acid production. After several refinements, this method, called the "lead chamber process" or "chamber process", remained the standard for sulfuric acid production for almost two centuries.

Sulfuric acid created by John Roebuck's process approached a 65% concentration. Later refinements to the lead chamber process by French chemist Joseph Louis Gay-Lussac and British chemist John Glover improved the yield to 78%. However, the manufacture of some dye s and other chemical processes require a more concentrated product. Throughout the 18th century, this could only be made by dry distillation|dry distilling minerals in a technique similar to the original alchemy|alchemical processes. Pyrite (iron disulfide, ) was heated in air to yield iron(II) sulfate , , which was oxidized by further heating in air to form iron(III) sulfate , Fe₂(SO₄)₃, which, when heated to 480& nbsp;°C, decomposed to iron(III) oxide and sulfur trioxide, which could be passed through water to yield sulfuric acid in any concentration. However, the expense of this process prevented the large-scale use of concentrated sulfuric acid.

In 1831, British vinegar merchant Peregrine Phillips patented the contact process , which was a far more economical process for producing sulfur trioxide and concentrated sulfuric acid. Today, nearly all of the world's sulfuric acid is produced using this method.

Physical properties

Grades of sulfuric acid

Although nearly 99% sulfuric acid can be made, this loses at the boiling point to produce 98.3% acid. The 98% grade is more stable in storage, and is the usual form of what is described as "concentrated sulfuric acid." Other concentrations are used for different purposes. Some common concentrations are:

Mass fraction H_2SO₄	Density (kg/ L)	Concentration (mol/ L)	Common name
10%
29–32%
62–70%
78–80%
98%

"Chamber acid" and "tower acid" were the two concentrations of sulfuric acid produced by the lead chamber process , chamber acid being the acid produced in lead chamber itself (<70% to avoid contamination with nitrosylsulfuric acid ) and tower acid being the acid recovered from the bottom of the Glover tower. They are now obsolete as commercial concentrations of sulfuric acid, although they may be prepared in the laboratory from concentrated sulfuric acid if needed. In particular, "10M" sulfuric acid (the modern equivalent of chamber acid, used in many titration s) is prepared by slowly adding 98% sulfuric acid to an equal volume of water, with good stirring: the temperature of the mixture can rise to 80& nbsp;°C (176& nbsp;°F) or higher.

When high concentrations of gas are added to sulfuric acid, , called pyrosulfuric acid , fuming sulfuric acid or oleum or, less commonly, Nordhausen acid , is formed. Concentrations of oleum are either expressed in terms of % (called % oleum) or as % (the amount made if were added); common concentrations are 40% oleum (109% ) and 65% oleum (114.6% ). Pure is a solid with melting point 36& nbsp;°C.

Pure sulfuric acid is a viscous clear liquid, like oil, and this explains the old name of the acid ('oil of vitriol').

Commercial sulfuric acid is sold in several different purity grades. Technical grade is impure and often colored, but is suitable for making fertilizer. Pure grades such as United States Pharmacopeia (USP) grade are used for making pharmaceutical s and dye stuffs. Analytical chemistry|Analytical grades are also available.

Polarity and conductivity

Anhydrous is a very Chemical polarity|polar liquid, having a dielectric constant of around 100. It has a high electrical conductivity , caused by dissociation through protonation|protonating itself, a process known as autoprotolysis .
: 2 + The equilibrium constant for the autoprotolysis is
:K_ap(25& nbsp;°C)= = .

The comparable Self-ionization of water|equilibrium constant for water , K_w is 10^-14, a factor of 10¹⁰ (10 billion) smaller.

In spite of the viscosity of the acid, the effective Molar conductivity|conductivities of the and ions are high due to an intra-molecular proton-switch mechanism (analogous to the Grotthuss mechanism in water), making sulfuric acid a good conductor. It is also an excellent solvent for many reactions.

The chemical equilibrium|equilibrium is actually more complex than shown above; 100% contains the following species at equilibrium (figures shown as millimoles per kilogram of solvent):

(15.0), (11.3), (8.0), (4.4), (3.6), (0.1).

Chemical properties

Reaction with water and dehydrating property

The hydration reaction of sulfuric acid is highly exothermic reaction|exothermic . One should always add the acid to the Properties of water|water rather than the water to the acid. Because the reaction is in an equilibrium that favors the rapid protonation of water, addition of acid to the water ensures that the acid is the limiting reagent. This reaction is best thought of as the formation of hydronium ions:

: + ? + HSO₄^- & nbsp;& nbsp; K₁ = 2.4 & nbsp; (strong acid)

: HSO₄^- + ? + SO₄^2- & nbsp;& nbsp;& nbsp; K₂ = 1.0& nbsp;

HSO₄^- is the bisulfate anion and SO₄^2- is the sulfate anion. K₁ and K₂ are the acid dissociation constant s.

Because the hydration of sulfuric acid is thermodynamic ally favorable and the affinity of it for water (molecule)|water is sufficiently strong, sulfuric acid is an excellent dehydrating agent. Concentrated sulfuric acid has a very powerful Dehydration reaction|dehydrating property, removing water ( Hydrogen|H₂ oxygen|O ) from other compound s including sugar and other carbohydrate s and producing carbon , heat, steam, and a more dilute acid containing increased amounts of hydronium and bisulfate ions.

In laboratory , this is often demonstrated by mixing table sugar (sucrose) into sulfuric acid. The sugar changes from white to dark brown and then to black as carbon is formed. A rigid column of black, porous carbon will emerge as well.. YouTube. Retrieved on 2011-07-18.

:C₁₂H₂₂O₁₁ (white sucrose) + sulfuric acid ? 12 C_{(black graphitic foam)} + 11 H₂O (steam) + sulfuric acid/water mixture

Similarly, mixing starch into concentrated sulfuric acid will give elemental carbon and water as absorbed by the sulfuric acid (which becomes slightly diluted). The effect of this can be seen when concentrated sulfuric acid is spilled on paper which is composed of cellulose ; the cellulose reacts to give a combustion|burnt appearance, the carbon appears much as soot would in a fire.
The carbon will smell strongly of caramel (aroma)|caramel due to the heat generated. Although less dramatic, the action of the acid on cotton , even in diluted form, will destroy the fabric.

:() n + sulfuric acid ? 6 n C + 5 n
The reaction with copper(II) sulfate can also demonstrate the dehydration property of sulfuric acid. The blue crystal is changed into white powder as water is removed.
:CuSO₄·5H₂O (blue crystal) + sulfuric acid ? CuSO₄ (white powder) + 5 H₂O

Acid-base properties

As an acid, sulfuric acid reacts with most base (chemistry)|bases to give the corresponding sulfate. For example, the blue copper salt copper(II) sulfate , commonly used for electroplating and as a fungicide , is prepared by the reaction of copper(II) oxide with sulfuric acid:

: CuO (s) + (aq) ? (aq) + (l)

Sulfuric acid can also be used to displace weaker acids from their salts. Reaction with sodium acetate , for example, displaces acetic acid , , and forms sodium bisulfate :

: + ? +
Similarly, reacting sulfuric acid with potassium nitrate can be used to produce nitric acid and a precipitate of potassium bisulfate . When combined with nitric acid , sulfuric acid acts both as an acid and a dehydrating agent, forming the nitronium ion , which is important in nitration reactions involving electrophilic aromatic substitution . This type of reaction, where protonation occurs on an oxygen atom, is important in many organic chemistry reactions, such as Fischer esterification and dehydration of alcohols.

Reactions with metals and strong oxidizing property

Dilute sulfuric acid reacts with metals via a single displacement reaction as with other typical acid s, producing hydrogen gas and salt s (the metal sulfate). It attacks reactive metals (metals at positions above copper in the reactivity series ) such as iron , aluminium , zinc , manganese , magnesium and nickel .
: Fe (s) + (aq) ? (g) + (aq)

However, concentrated sulfuric acid is a oxidizing agent|strong oxidizing agent in which it does not react with metals in the same way as other typical acid s. Sulfur dioxide , water and SO₄^2- ions are evolved instead of the hydrogen and salt s.
: 2 H₂SO₄ + 2 e^- ? SO₂ + 2 H₂O + SO₄^2-

It can oxidize non-active metals such as tin and copper , depending upon the temperature of it like the nitric acid .
:Cu + 2 H₂SO₄ ? SO₂ + 2 H₂O + SO₄^2- + Cu²⁺

As shown above, the concentrated sulfuric acid is a oxidizing agent|strong oxidizing agent , especially when hot in which the acid itself carries out redox|reduction whereas the dilute one acts a typical acid where the H⁺ is the oxidizing agent so the oxidizing property of it is not as powerful as the concentrated one.

Lead and tungsten , however, are resistant to sulfuric acid.

Reactions with non-metals

Hot concentrated sulfuric acid oxidizes non-metals such as carbon and sulfur .
:C + 2 H₂SO₄ ? CO₂ + 2 SO₂ + 2 H₂O
:S + 2 H₂SO₄ ? 3 SO₂ + 2 H₂O

Reaction with sodium chloride

It reacts with sodium chloride , and gives hydrogen chloride gas and sodium bisulfate :

:NaCl + H₂SO₄ ? NaHSO₄ + HCl

Electrophilic aromatic substitution

Benzene undergoes electrophilic aromatic substitution with sulfuric acid to give the corresponding sulfonic acid s:

Occurrence

Pure sulfuric acid is not encountered naturally on Earth in anhydrous form, due to its great Hygroscopy|affinity for water . Dilute sulfuric acid is a constituent of acid rain , which is formed by atmospheric Redox|oxidation of sulfur dioxide in the presence of water (molecule)|water – i.e., oxidation of sulfurous acid . Sulfur dioxide is the main byproduct produced when sulfur-containing fuels such as coal or oil are burned.

Sulfuric acid is formed naturally by the oxidation of sulfide minerals, such as iron sulfide. The resulting water can be highly acidic and is called acid mine drainage (AMD) or acid rock drainage (ARD). This acidic water is capable of dissolving metals present in sulfide ores, which results in brightly colored, toxic streams. The oxidation of pyrite (iron sulfide) by molecular oxygen produces iron(II), or :

:2 (s) + 7 + 2 ? 2 (aq) + 4 (aq) + 4
The can be further oxidized to :

:4 + + 4 ? 4 + 2
The produced can be precipitated as the hydroxide or hydrous iron oxides|hydrous oxide :

: (aq) + 3 ? (s) + 3
The iron(III) ion ("ferric iron") can also oxidize pyrite:

: (s) + 14 + 8 ? 15 (aq) + 2 (aq) + 16
When iron(III) oxidation of pyrite occurs, the process can become rapid. pH values below zero have been measured in ARD produced by this process.

ARD can also produce sulfuric acid at a slower rate, so that the acid neutralizing capacity (ANC) of the aquifer can neutralize the produced acid. In such cases, the total dissolved solids (TDS) concentration of the water can be increased from the dissolution of minerals from the acid-neutralization reaction with the minerals.

Sulfuric acid is used as a defence by certain marine species, for example, the phaeophyte alga Desmarestia munda (order Desmarestiales ) concentrates sulfuric acid in cell vacuoles.

Extraterrestrial sulfuric acid

Venus

Sulfuric acid is produced in the upper atmosphere of Venus by the Sun 's photochemistry|photochemical action on carbon dioxide , sulfur dioxide , and water vapor. Ultraviolet photon s of wavelengths less than 169& nbsp; nanometre|nm can photodissociation|photodissociate carbon dioxide into carbon monoxide and atomic oxygen . Atomic oxygen is highly reactive. When it reacts with sulfur dioxide, a trace component of the Venusian atmosphere, the result is sulfur trioxide , which can combine with water vapor, another trace component of Venus's atmosphere, to yield sulfuric acid. In the upper, cooler portions of Venus's atmosphere, sulfuric acid exists as a liquid, and thick sulfuric acid clouds completely obscure the planet's surface when viewed from above. The main cloud layer extends from 45–70& nbsp;km above the planet's surface, with thinner hazes extending as low as 30& nbsp;km and as high as 90& nbsp;km above the surface. The permanent Venusian clouds produce a concentrated acid rain, as the clouds in the atmosphere of Earth produce water rain.

The atmosphere exhibits a sulfuric acid cycle. As sulfuric acid rain droplets fall down through the hotter layers of the atmosphere's temperature gradient, they are heated up and release water vapor, becoming more and more concentrated. When they reach temperatures above 300& nbsp;°C, sulfuric acid begins to decompose into sulfur trioxide and water, both in the gas phase. Sulfur trioxide is highly reactive and dissociates into sulfur dioxide and atomic oxygen, which oxidizes traces of carbon monoxide to form carbon dioxide. Sulfur dioxide and water vapor rise on convection currents from the mid-level atmospheric layers to higher altitudes, where they will be transformed again into sulfuric acid, and the cycle repeats.

Europa

Infrared spectra from NASA 's Galileo (spacecraft)|Galileo mission show distinct absorptions on Jupiter 's moon Europa (moon)|Europa that have been attributed to one or more sulfuric acid hydrates. Sulfuric acid in solution with water causes significant freezing-point depression of water's melting point , down to , and this would make more likely the existence of liquid solutions beneath Europa's icy crust.The interpretation of the spectra is somewhat controversial. Some planetary scientists prefer to assign the spectral features to the sulfate ion, perhaps as part of one or more minerals on Europa's surface.

Manufacture

Sulfuric acid is produced from sulfur , oxygen and water via the conventional contact process (DCDA) or the wet sulfuric acid process (WSA).

Contact process

In the first step, sulfur is burned to produce sulfur dioxide.
: S (s) + (g) ? (g)

This is then oxidized to sulfur trioxide using oxygen in the presence of a vanadium(V) oxide catalyst . This reaction is reversible and the formation of the sulfur trioxide is exothermic.
: 2 (g) + (g) 2 (g) (in presence of )

The sulfur trioxide is absorbed into 97–98% to form oleum (), also known as fuming sulfuric acid. The oleum is then diluted with water to form concentrated sulfuric acid.

: (l) + (g)? (l)

: (l) + (l) ? 2 (l)

Note that directly dissolving in water is not practical due to the highly Exothermic reaction|exothermic nature of the Chemical reaction|reaction between sulfur trioxide and water. The reaction forms a corrosive aerosol that is very difficult to separate, instead of a liquid.

: (g) + (l) ? (l)

Wet sulfuric acid process

In the first step, sulfur is burned to produce sulfur dioxide:
: S(s) + (g) ? (g)

or, alternatively, hydrogen sulfide () gas is incinerated to gas:
: 2 + 3 ? 2 + 2 (-518& nbsp;kJ/mol)
This is then oxidized to sulfur trioxide using oxygen with vanadium(V) oxide as catalyst .
: 2 + ? 2 (-99& nbsp;kJ/mol) (reaction is reversible)

The sulfur trioxide is hydrated into sulfuric acid :
: + ? (g) (-101& nbsp;kJ/mol)

The last step is the condensation of the sulfuric acid to liquid 97–98% :
: (g) ? (l) (-69& nbsp;kJ/mol)

Other methods

Another method is the less well-known metabisulfite method, in which metabisulfite is placed at the bottom of a beaker, and 12.6 molar concentration hydrochloric acid is added. The resulting gas is bubbled through nitric acid, which will release brown/red vapors. The completion of the reaction is indicated by the ceasing of the fumes. This method does not produce an inseparable mist, which is quite convenient.

Sulfuric acid can be produced in the laboratory by burning sulfur in air and dissolving the gas produced in a hydrogen peroxide solution.

: SO₂ + H₂O₂ ? H₂SO₄

Prior to 1900, most sulfuric acid was manufactured by the lead chamber process . As late as 1940, up to 50% of sulfuric acid manufactured in the United States was produced by chamber process plants.

In early to mid 19th century "vitriol" plants existed, among other places, in Prestonpans Scotland, Shropshire and the Lagan Valley in County Anrim Ireland where it was used as a bleach for linen. Early bleaching of linen was done using milk but this was a slow process and the use of vitriol speeded up the bleaching process.

Uses

Sulfuric acid is a very important commodity chemical, and indeed, a nation's sulfuric acid production is a good indicator of its industrial strength. World production in 2004 was about 180 million tonne s, with the following geographic distribution: Asia 35%, North America (including Mexico) 24%, Africa 11%, Western Europe 10%, Eastern Europe and Russia 10%, Australia and Oceania 7%, South America 7%. Most of this amount (~60%) is consumed for fertilizers, particularly superphosphates, ammonium phosphate and ammonium sulfates. About 20% is used in chemical industry for production of detergents, synthetic resins, dyestuffs, pharmaceuticals, petroleum catalysts, insecticides and antifreeze , as well as in various processes such as oil well acidicizing, aluminium reduction, paper sizing, water treatment. About 6% of uses are related to pigment s and include paints, Enamel paint|enamel s, printing inks, coated fabrics and paper, and the rest is dispersed into a multitude of applications such as production of explosives, cellophane , acetate and viscose textiles, lubricants, non-ferrous metals and batteries.

Industrial production of chemicals

The major use for sulfuric acid is in the "wet method" for the production of phosphoric acid , used for manufacture of phosphate fertilizer s. In this method, phosphate rock is used, and more than 100 million tonnes are processed annually. This raw material is shown below as fluorapatite , though the exact composition may vary. This is treated with 93% sulfuric acid to produce calcium sulfate , hydrogen fluoride (HF) and phosphoric acid . The HF is removed as hydrofluoric acid . The overall process can be represented as:

: + 5 + 10 ? 5 + HF + 3
Ammonium sulfate , an important nitrogen fertilizer, is most commonly produced as a byproduct from Coke (fuel)|coking plants supplying the iron and steel making plants. Reacting the ammonia produced in the thermal decomposition of coal with waste sulfuric acid allows the ammonia to be crystallized out as a salt (often brown because of iron contamination) and sold into the agro-chemicals industry.

Another important use for sulfuric acid is for the manufacture of aluminium sulfate , also known as paper maker's alum. This can react with small amounts of soap on paper pulp fibers to give gelatinous aluminium carboxylate s, which help to coagulate the pulp fibers into a hard paper surface. It is also used for making aluminium hydroxide , which is used at water treatment plants to filter (water)|filter out impurities, as well as to improve the taste of the water . Aluminium sulfate is made by reacting bauxite with sulfuric acid:

: + 3 ? + 3
Sulfuric acid is also important in the manufacture of dye stuffs solutions.

Sulfur-iodine cycle

The sulfur-iodine cycle is a series of thermo-chemical processes used to obtain hydrogen . It consists of three chemical reactions whose net reactant is water and whose net products are hydrogen and oxygen .
:{|
|-
| 2 ? 2 + 2 + || & nbsp;& nbsp;& nbsp; || (830& nbsp;°C)
|-
| + + 2 ? 2 HI + || & nbsp;& nbsp;& nbsp; || (120& nbsp;°C)
|-
| 2 HI ? + || & nbsp;& nbsp;& nbsp; || (320& nbsp;°C)
|}

The sulfur and iodine compounds are recovered and reused, hence the consideration of the process as a cycle. This process is endothermic and must occur at high temperatures, so energy in the form of heat has to be supplied.

The sulfur-iodine cycle has been proposed as a way to supply hydrogen for a hydrogen economy|hydrogen-based economy . It does not require hydrocarbons like current methods of steam reforming . But note that all of the available energy in the hydrogen so produced is supplied by the heat used to make it.

The sulfur-iodine cycle is currently being researched as a feasible method of obtaining hydrogen, but the concentrated, corrosive acid at high temperatures poses currently insurmountable safety hazards if the process were built on a large scale.

Industrial cleaning agent

Sulfuric acid is used in large quantities by the iron and steel making industry to remove oxidation, rust and scaling from rolled sheet and billets prior to sale to the automobile and major appliances industry. Used acid is often recycled using a spent acid regeneration (SAR) plant. These plants combust spent acid with natural gas, refinery gas, fuel oil or other fuel sources. This combustion process produces gaseous sulfur dioxide () and sulfur trioxide () which are then used to manufacture "new" sulfuric acid. SAR plants are common additions to metal smelting plants, oil refineries, and other industries where sulfuric acid is consumed in bulk, as operating a SAR plant is much cheaper than the recurring costs of spent acid disposal and new acid purchases.

Catalyst

Sulfuric acid is used for a variety of other purposes in the chemical industry. For example, it is the usual acid catalyst for the conversion of cyclohexanone oxime to caprolactam , used for making nylon . It is used for making hydrochloric acid from salt via the Mannheim process . Much is used in petroleum refining, for example as a catalyst for the reaction of isobutane with isobutylene to give isooctane , a compound that raises the octane rating of gasoline (petrol).

Electrolyte

Sulfuric acid acts as the electrolyte in lead-acid batteries|lead-acid (car) batteries (lead-acid accumulator):

At anode :
: + + 2 e^-

At cathode :
: + 4 H⁺ + + 2 e^- + 2 H₂O

Overall:
: + + 4 H⁺ + 2 2 + 2 H₂O

Domestic uses

Sulfuric acid is hygroscopic which readily absorbs atmospheric water vapour and hence it is usually used as a drying agent . Besides, it is used as a general dehydrating agent in its concentrated form due to its strong dehydrating property.

Concentrated sulfuric acid is frequently the major ingredient in drain cleaner|acidic drain cleaners which are used to remove lipids|grease , hair , tissue paper , etc. But they are advised to be used by licensed plumbers because of safety considerations.

Health

Sulfuric acid and sulfonated phenolics are the primary ingredients in Debacterol , a liquid topical agent that is used in the treatment of Recurrent Aphthous Stomatitis (canker sores) or for any procedures in the oral cavity which require controlled, focal debridement of necrotic tissues. Application completely stops oral ulcer pain, seals damaged oral mucosal tissues and aids natural healing processes after just one application, which requires only minutes to perform (actual application time is only 5 seconds). Although Debacterol can only be purchased and administered by a licensed medical or dental professional, concentrated 98% sulfuric acid alone is also extremely effective in achieving the same results. Although 98% sulfuric acid can be purchased online by anyone, much caution must be taken since it is a dangerous substance. The area around the sore must be thoroughly dried, and the applicator should have a small tip and be made of a material that does not react with sulfuric acid (such as glass). A sufficient amount can be obtained by just wetting the tip of the applicator, and much care must be taken to not damage too much of the surrounding tissue. The initial contact with the sore is extremely painful, but the relief from ulcer pain is immediate and complete. The resulting damaged tissue is not painful and heals much more quickly than an untreated sore.

Safety

Laboratory hazards

Sulfuric acid is highly corrosive and can cause very severe chemical burn upon contact as it decomposes proteins and lipids via amide hydrolysis and ester hydrolysis readily, like what other corrosive strong acids and alkali|strong alkalis do. Yet, its corrosiveness is also accentuated by its dehydration|dehydrating property in which it can dehydrate the carbohydrates in Tissue (biology)|organisms’ tissues as well, liberating heat and posing secondary thermal burn in addition to the chemical burn. Due to such reasons, damage caused by sulfuric acid is potentially more serious than that of other comparable strong acids (e.g. hydrochloric acid , nitric acid ). If it contacts eyes, permanent blindness may result and it can cause irreversible damage to internal organs and may be fatal if swallowed. Protective equipment s should always be used when handling the acid.
Moreover, sulfuric acid at a high concentration is a strong oxidizing agent being corrosive to many metal s which should be stored carefully .

The danger is greater with more concentrated preparations of sulfuric acid. Solutions equal to or stronger than 1.5& nbsp;M are labeled "CORROSIVE", while solutions greater than 0.5& nbsp;M but less than 1.5& nbsp;M are labeled "IRRITANT". However, even the normal laboratory "dilute" grade (approximately 1& nbsp;M, 10%) will char paper by dehydration if left in contact for a sufficient time.

The standard first aid treatment for acid spills on the skin is, as for other corrosion|corrosive agents, irrigation with large quantities of water. Washing is continued for at least ten to fifteen minutes to cool the tissue surrounding the acid burn and to prevent secondary damage. Contaminated clothing is removed immediately and the underlying skin washed thoroughly.

Preparation of the diluted acid can also be dangerous due to the heat released in the dilution process. The concentrated acid is always added to water and not the other way around, to take advantage of the relatively high heat capacity of water. Addition of water to concentrated sulfuric acid leads to the dispersal of a sulfuric acid aerosol or worse, an explosion . Preparation of solutions greater than 6& nbsp;M (35%) in concentration is most dangerous, as the heat produced may be sufficient to boil the diluted acid: efficient mechanical stirring and external cooling (such as an ice bath) are essential.

On a laboratory scale, sulfuric acid can be diluted by pouring concentrated acid onto crushed ice made from de-ionized water. The ice melts in an endothermic process while dissolving the acid. The amount of heat needed to melt the ice in this process is greater than the amount of heat evolved by dissolving the acid so the solution remains cold. After all the ice has melted, further dilution can take place using water.

Pure sulfuric acid should be safely stored in glass vessels or bottles.

Industrial hazards

Although sulfuric acid is non-flammable, contact with metals in the event of a spillage can lead to the liberation of hydrogen gas. The dispersal of acid aerosols and gaseous sulfur dioxide is an additional hazard of fires involving sulfuric acid.

The main occupational of risks posed by this acid are skin contact leading to burns (see above) and the inhalation of aerosols. Exposure to aerosols at high concentrations leads to immediate and severe irritation of the eyes, respiratory tract and mucous membranes: this ceases rapidly after exposure, although there is a risk of subsequent pulmonary edema if tissue damage has been more severe. At lower concentrations, the most commonly reported symptom of chronic exposure to sulfuric acid aerosols is erosion of the teeth, found in virtually all studies: indications of possible chronic damage to the respiratory tract are inconclusive as of 1997. In the United States, the permissible exposure limit (PEL) for sulfuric acid is fixed at 1& nbsp;mg/m³: limits in other countries are similar. There have been reports of sulfuric acid ingestion leading to vitamin B12 deficiency with subacute combined degeneration. The spinal cord is most often affected in such cases, but the optic nerves may show demyelination , loss of axon s and gliosis .

Legal restrictions

International commerce of sulfuric acid is controlled under the United Nations Convention Against Illicit Traffic in Narcotic Drugs and Psychotropic Substances|United Nations Convention Against Illicit Traffic in Narcotic Drugs and Psychotropic Substances, 1988 , which lists sulfuric acid under Table II of the convention as a chemical frequently used in the illicit manufacture of narcotic drugs or psychotropic substances., 11th Edition, January 2007 (p. 4). International Narcotics Control Board . Vienna, Austria ; 2007.

In the US sulfuric acid is included in DEA list of chemicals#List II chemicals|List II of the DEA list of chemicals|list of essential or precursor chemicals established pursuant to the Chemical Diversion and Trafficking Act . Accordingly, transactions of sulfuric acid—such as sales, transfers, exports from and imports to the United States—are subject to regulation and monitoring by the Drug Enforcement Administration . 17 October 2001.

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