Name: Sulfuric Acid
CAS No: Sulfuric acid [7664-93-9].
BP: Sulphuric Acid PhEur: Sulphuric Acid USP-NF: Sulfuric Acid
Acidum sulfuricum; E513; hydrogen sulfate; oil of vitriol.
Sulfuric acid [7664-93-9].
H2SO4 98.08
See Section 4.
Sulfuric acid is used as an acidifying agent in a variety of pharmaceutical and food preparations. It may also be used to prepare dilute sulfuric acid, which, in addition to its use as an excipient, has some therapeutic use for the treatment of gastric hypoacidity, as an astringent in diarrhea, or to stimulate appetite. Sulfuric acid has been used in parenteral, oral, topical, and ophthalmic pharmaceutical formulations.
Sulfuric acid occurs as a clear, colorless, odorless, oily liquid. It is very corrosive and has a great affinity for water. The USP32–NF27 specifies that sulfuric acid contains not less than 95% and not more than 98%, by weight, of H2SO4; the remainder is water
See Table I.
Boiling point 2908C for H2SO4 (95%–98% w/w); 3308C for H2SO4 (100% w/w). Density 1.84 g/cm3 at 208C Dissociation constant pKa1 = 3.00; pKa2 = 1.99. Freezing point 108C for H2SO4 (100% w/w); 38C for H2SO4 (98% w/w); 328C for H2SO4 (93% w/w). Solubility Miscible with ethanol and water. Vapor density 3.4 (air = 1.0) Vapor pressure <0.3 mmHg at 208C
Sulfuric acid is stable but very corrosive and hygroscopic. It will draw moisture from the atmosphere. Sulfuric acid should be stored in a tightly closed container in an explosion-proof area. Containers should be stored out of direct sunlight and away from heat. Avoid heat and moisture. Isolate from incompatible materials
Avoid storage in close proximity to water, most common metals, organic materials, strong reducing agents, combustible materials, strong bases, carbonates, sulfides, cyanides, strong oxidizing agents, and carbides. Sulfuric acid is a powerful oxidizer and may ignite or explode on contact with many materials. It can react violently with the evolution of a large amount of heat. Oxides of sulfur and hydrogen can be generated during reactions. Great care must be exercised when mixing with other liquids. Always add sulfuric acid to the diluent with great caution
Sulfuric acid may be prepared industrially by either the contact process or the chamber process.(1,2) Contact Process 2SO2 þO2 !2SO3 SO3 þH2O ! H2SO4 Chamber Process 2NO þ O2 ! 2NO2 NO2 þ SO2 þ H2O ! H2SO4 þ NO
Sulfuric acid is widely used in a variety of pharmaceutical formulations. Although concentrated sulfuric acid is very corrosive, it is normally used well diluted in formulations. Concentrated sulfuric acid will react violently with water and much heat is generated. When diluting sulfuric acid, the acid should always be added to the other liquid with great caution. The concentrated solution is extremely corrosive and can cause severe damage or necrosis on contact with the eyes and skin. Ingestion may cause severe injury or death. Inhalation of concentrated vapors can cause serious lung damage. LD50 (rat, oral): 2.14 g/kg(3
Caution should be exercised when handling sulfuric acid and suitable protection against inhalation and spillage should be made. Respiratory protection may not be required where adequate ventilation exists. Eye protection (safety goggles and face shield), rubber gloves, and apron are recommended, depending on the circumstances and quantity of sulfuric acid handled. Do not dilute spills of concentrated acid with water since an exothermic reaction will occur. Spills should be neutralized with soda ash or lime. Splashes on the skin and eyes should be treated by immediate and prolonged washing (10–15 minutes) with large amounts of water, and medical attention should be sought. Do not neutralize acid in contact with skin or eyes as the exothermic reaction can increase the severity of the burn. Remove contaminated clothing immediately. Fumes can cause irritation or permanent damage to the eyes, nose, and respiratory system; prolonged exposure to fumes may damage the lungs.
GRAS listed. Accepted for use as a food additive in Europe. Included in the FDA Inactive Ingredients Database (IM, IV, and IP injections, inhalation solutions, irrigation solutions, nasal, ophthalmic solutions and suspensions, oral solutions, and topical emulsions and creams). Included in nonparenteral and parenteral medicines licensed in Europe. Included in the Canadian List of Acceptable Non-medicinal Ingredients. The United Nations Convention Against Illicit Traffic in Narcotic Drugs and Psychotropic Substances (1988) lists sulfuric acid as a chemical frequently used in the illicit manufacture of narcotic drugs or psychotropic substances.(4) In the USA, sulfuric acid is included in the list of essential or precursor chemicals established pursuant to the Chemical Diversion and Trafficking Act. Accordingly, transactions of sulfuric acid such as imports, exports, sales, and transfers are subject to regulation and monitoring by the Drug Enforcement Administration.(5
Dilute sulfuric acid; fuming sulfuric acid. Dilute sulfuric acid Density 1.062–1.072 g/cm3 Comments Prepared by adding 104 g of sulfuric acid to 896 g of purified water with constant stirring and cooling. Dilute sulfuric acid contains between 9.5% and 10.5% w/w of H2SO4. Fuming sulfuric acid Synonyms oleum. Comments Fuming sulfuric acid consists of H2SO4 with free sulfur trioxide (SO3). It is prepared by adding sulfur trioxide to sulfuric acid. Available in grades containing up to about 80% free SO3. Fuming sulfuric acid is a colorless or slightly colored, viscous liquid that emits choking fumes of sulfur trioxide. It is extremely corrosive and should be handled with great care and stored in tightly closed glass-stoppered bottles.
A specification for sulfuric acid is contained in the Food Chemicals Codex (FCC).(6) The EINECS number for sulfuric acid is 231-639-5. The PubChem Compound ID (CID) for sulfuric acid is 1118.