Sulfuric acid

Molecular Structure:

Molecular Formula: H₂O₄S
Molecular Weight: 98.0785
IUPAC Name: Sulfuric acid
Synonyms of Sulfuric acid (CAS NO.7664-93-9): Oil of vitriol ; Sulfuric acid [Strong inorganic acid mists containing sulfuric acid] ; Sulfuric acid contained in strong inorganic acid mists ; Sulfuric acid with >51% acid ; Sulfuric acid with >51% acid [UN1830] [Corrosive] ; Sulfuric acid with not >51% acid ; Sulfuric acid with not >51% acid [UN2796] [Corrosive] ; Sulfuric acid, spent ; Sulfuric acid, spent [UN1832] [Corrosive] ; UN1830 ; UN1832 ; UN2796 ; sulfuric acid (acid aerosols including mists, vapors, gas, fog and other airborne forms of any particle size)
CAS NO: 7664-93-9
Classification Code: Agricultural Chemical ; Herbicide ; Human Data ; Mutation data ; Pharmaceutic aid [acidifying agent] ; Reproductive Effect ; Skin / Eye Irritant ; Tumor data
Melting point: 10°C 
Index of Refraction: 1.537
Molar Refractivity: 13.92 cm³
Molar Volume: 44.5 cm³
Surface Tension: 124.1 dyne/cm
Density: 2.2 g/cm³
Enthalpy of Vaporization: 62.94 kJ/mol
Boiling Point: 330 °C at 760 mmHg
Vapour Pressure: 3.35E-05 mmHg at 25°C

The discovery of sulfuric acid is credited to the 8th century Muslim chemist and alchemist, Jabir ibn Hayyan (Geber). The acid was later studied by 9th century Persian physician and alchemist Ibn Zakariya al-Razi (Rhazes), who obtained the substance by dry distillation of minerals including iron(II) sulfate heptahydrate, FeSO₄·7H₂O, and copper(II) sulfate pentahydrate, CuSO₄·5H₂O.
In the 17th century, the German-Dutch chemist Johann Glauber prepared sulfuric acid by burning sulfur together with saltpeter (potassium nitrate, KNO₃), in the presence of steam
Sulfuric acid created by John Roebuck's process only approached a 35–40% 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%.
Throughout the 18th century, this could only be made by dry distilling minerals in a technique similar to the original alchemical processes.
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.

Although sulfur is the common starting raw material, other sources of Sulfuric acid (CAS NO.7664-93-9) can be used, including iron, copper, lead, nickel, and zinc sulfides. Hydrogen sulfide, a by-product of petroleum refining and natural gas refining, can be burned to sulfur dioxide. Gypsum (CaSO₄) can also be used but needs high temperatures to be converted to sulfur dioxide. Other uses for it include the manufacture of fertilizers, chemicals, inorganic pigments, petroleum refining, etching, as a catalyst in alkylation processes, in electroplating baths, for pickling and other operations in iron and steel production, in rayon and film manufacture, in the making of explosives, and in nonferrous metallurgy

The manufacture of Sulfuric acid (CAS NO.7664-93-9) by the lead chamberprocess involves oxidation of sulfur to sulfur dioxide by oxygen, further oxidation of sulfur dioxide to sulfur trioxide with nitrogen dioxide, and, finally, hydrolysis of sulfur trioxide.
             S + O₂ → SO₂
             2NO + O₂→ 2NO₂
          SO₂ + NO₂ → SO₃ + NO
           SO₃ + H₂O → H₂SO₄
Modifications of the process include towers to recover excess nitrogen oxides and to increase the final acid concentration from 65% (chamber acid) to 78% (tower acid).
 The contact process has evolved to become the method of choice for sulfuric acid manufacture  because of the ability of the process to produce stronger acid.
              S + O₂ → SO₂
           2SO₂ + O₂ → 2SO₃
           SO₃ + H₂O → H₂SO₄
In the process, sulfur and oxygen are converted to sulfur dioxide at 1000 °C and then cooled to 420 °C. The sulfur dioxide and oxygen enter the converter, which contains a catalyst such as vanadium pentoxide (V₂O₅). About 60 to 65% of the sulfur dioxide is converted by an exothermic reaction to sulfur trioxide in the first layer with a 2 to 4-second contact time. The gas leaves the converter at 600°C and is cooled to 400°C before it enters the second layer of catalyst. After the third layer, about 95% of the sulfur dioxide is converted into sulfur trioxide. The mixture is then fed to the initial absorption tower, where the sulfur trioxide is hydrated to sulfuric acid after which the gas mixture is reheated to 420 °C and enters the fourth layer of catalyst that gives overall a 99.7% conversion of sulfur dioxide to sulfur trioxide. It is cooled and then fed to the final absorption tower and hydrated to sulfuric acid. The final sulfuric acid concentration is 98 to 99% (1 to 2% water). A small amount of this acid is recycled by adding some water and recirculating into the towers to pick up more sulfur trioxide.

Reported in EPA TSCA Inventory.

Hazard Codes of Sulfuric acid (CAS NO.7664-93-9): C,T,F,Xi
Risk Statements: 36/38-35-39-23/24/25-11 
R36/38: Irritating to eyes and skin. 
R35: Causes severe burns. 
R39: Danger of very serious irreversible effects. 
R23/24/25: Toxic by inhalation, in contact with skin and if swallowed. 
R11: Highly flammable.
Safety Statements: 26-30-45-36/37-16 
S26: In case of contact with eyes, rinse immediately with plenty of water and seek medical advice. 
S30: Never add water to this product. 
S45: In case of accident or if you feel unwell, seek medical advice immediately (show the label whenever possible.) 
S36/37: Wear suitable protective clothing and gloves. 
S16: Keep away from sources of ignition.
RIDADR: UN 3264 8/PG 3
WGK Germany: 1
RTECS: WS5600000
F: 3
HazardClass: 8
PackingGroup: II
HS Code: 28070010
Suspected human carcinogen when contained in strong inorganic mists. A human poison. Experimental poison by inhalation. Moderately toxic by ingestion. A severe eye irritant. Extremely irritating, corrosive, and toxic to tissue, resulting in rapid destruction of tissue, causing severe burns. If much of the skin is involved, exposure is accompanied by shock, collapse, and symptoms similar to those seen in severe burns. Repeated contact with dilute solutions can cause a dermatitis, and repeated or prolonged inhalation of a mist of sulfuric acid can cause inflammation of the upper respiratory tract, leading to chronic bronchitis. Sensitivity to sulfuric acid or its mists or vapors varies with individuals. Normally 0.125–0.50 ppm may be mildly annoying, 1.5–2.5 ppm can be definitely unpleasant, and 10–20 ppm is unbearable. Workers exposed to low concentrations of the vapor gradually lose their sensitivity to its irritating action. Inhalation of concentrated vapor or mists from hot acid or oleum can cause rapid loss of consciousness with serious damage to lung tissue. Severe exposure may cause a chemical pneumonitis; erosion of the teeth due to exposure to strong acid fumes has been recognized in industry. An experimental teratogen.

This is a very powerful acidic oxidizer that can ignite or explode on contact with many materials, e.g., acetic acid, acetone cyanhydrin, (acetone + HNO₃), (acetone + K₂Cr₂O₇), acetonitrile, acrolein, acrylonitrile, (acrylonitrile + H₂O), (alcohols + H₂O₂), allyl alcohol, allyl chloride, NH₄OH, 2-amino ethanol, NH₄, triperchromate, aniline, (bromates + metals), BrF₅, n-butyraldehyde, carbides, CoHC₂, chlorates, (metals + chlorates), ClF₃, chlorosulfonic acid, Cu₃N, diisobutylene, (dimethyl benzylcarbinol + H₂O₂), epichlorohydrin, ethylene cyanhydrin, ethylene diamine, ethylene glycol, ethylene imine, fulminates, HCl, H₂, IF₇, (indene + HNO₃), Fe, isoprene, Li₆Si₂, Hg₃N₂, mesityl oxide, metals, (HNO₃ + glycerides), p-nitrotoluene, perchlorates, HClO₄, (C₆H₆ + permanganates), pentasilver trihydroxydiamino phosphate, (1-phenyl-2-methyl propyl alcohol + H₂O₂), P, P(OCN)₃, picrates, potassium-tert-butoxide, KClO₃, KMnO₄, (KMnO₄ + KCl), (KMnO₄ + H₂O), β-propiolactone, RbHC₂, propylene oxide, pyridine, Na, Na₂CO₃, NaOH, steel, styrene monomer, water, vinyl acetate, (HNO₃ + toluene). When heated it emits highly toxic fumes; will react with water or steam to produce heat; can react with oxidizing or reducing materials. When heated to decomposition it emits toxic fumes of SO_x. See also SULFATES.

OSHA PEL: TWA 1 mg/m³
ACGIH TLV: TWA 1 mg/m³; STEL 3 mg/m³; Suspected Human Carcinogen (Contained in strong inorganic mists); (Proposed: TWA 0.2 mg/m³; Suspected Human Carcinogen (Contained in strong inorganic mists))
DFG MAK: 1 mg/m³
NIOSH REL: (Sulfuric Acid) TWA 1 mg/m³
DOT Classification:  8; Label: Corrosive

 Sulfuric acid (CAS NO.7664-93-9) ,its occupational chemical analysis uses OSHA: #ID-113 or NIOSH: Acids, inorganic, 7903.