Acids Sulfuric

Sulfuric acid is the most important and widely used inorganic chemical. The 1994 U.S. production of sulfuric acid was 89.2 billion pounds. 

Sulfuric acid is primarily used to make fertilizers. It is also used in other major industries such as detergents, paints, pigments, and pharmaceuticals. 

2-16 Sulfuric Acid Partial Pressure, bar, over Aqueous 

2-17 Total Pressure, bar, of Aqueous Sulfuric Acid Solutions.. 2-87 

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In its pure liquid state, sulfuric acid has a high electrical conductivity and high viscosity. Self-dissociation occurs in the pure liquid the reaction  

It has been estimated that the total amount of self-dissociation products is. 043 molal. in comparison with the 2.xl0 medal concentration of H and OH ions in water. 

In solution with water this polyprotic acid disscciates  

The first dissociation is usually treated as being complete however, at high concentrations of sulfuric acid, the acid may be said to be the solvent and the water the solute. The second dissociation prevails only in very low sulfuric acid concentrations. In 1949, Young and Blatz (HIS) presented the following diagram to describe the concentrations of the SO and HSO ions and undissociated acid ( HHSOi,) based on Raman spectrum measurements  

The second dissociation constant has been the subject of much study. Hamer (H5) estimated a value of. 0120 at 25 in 1934 based on his e.m.f. measurements of a cell containing NaHSOi., Na2SO and NaCl. The data was recalculated to take into consideration the NaSO complex in 1952 by Davies et al. (HI) which resulted in Kj( =. 0102. Robinson and Stokes (8) presented a temperature fit for the second ionization constant based on values presented by Singleterry (H13)  

DOT Label Corrosive Material, UN 1830, UN 1832 (for the concentrated and spent acids) 

Inhalation of its vapors or mist can pro-dnce severe bronchial constriction. Becanse the vapor pressnre of snlfnric acid is negligible, 0.001 torr at 20°C (68°F), the inhalation hazard is low. However, the acid mists, having a particle size of 7 pm, may penetrate the upper respiratory tract and nasal passage. Hnman exposure to acid mist at a concentration of 5 mg/m in air prodnced coughing. At concentrations of 1 mg/m, there was no irritation. Chronic exposnre to sulfuric acid mist may produce bronchitis, conjnnctivitis, skin lesions, and erosion of teeth. Freqnent contact with dilute acid can canse dermatitis of skin. 

Colorless, odorless, viscous oily liquid absorbs moisture from air abstracts water from many organic substances chars sugar and wood bp 338°C (640°F) decomposes at 340°C (644°F) to sulfur trioxide and water anhydrous acid freezes at 10°C (SOT) 98% acid freezes at 3°C (37°F) density 1.84 infinitely soluble in water and alcohol, evolving heat. 

Concentrated sulfuric acid is a very corrosive liquid that can cause severe, deep bums to 

LD50 value, oral (rats) 2140 mg/kg LC50 value, inhalation (rats) 510 mg/m /2 h 

The primar uses for hydrogen fluoride in the United States are in the manufacture of chlorofluorocarbons, aluminum fluoride, sodium aluminum fluoride (cryolite). md uranium tetrafluoride, and in petroleum alkylation. 

Sulfur dioxide is extremely stable to heat, even up to 3600°F. It docs not form flammable or cxplosi c mixtures witli air. It will, however, react with water or steam to produce toxic and corrosive fumcs. When the gas dissoh es in water it forms a weak acid solution of sulfurous acid (H2SO3), which is corrosi C and unstable when exposed to heat.  

TABLE 8.6.1 Physical Properties of Sulfur Dioxide (SO2) CAS Registry 

Additional properties useful in determining other properties from physical  

The deleterious effect of sulfur dioxide and sulfites in domestic water is increased corrosivity owing to the lowered pH. However, oxidation of sulfite to sulfate in aqueous solutions uses dissolved oxygen, and tliis may retard corrosion. While tlie oxidjition of sulfite and sulfurous acid to sulfate and sulfuric acid in the atmosphere is an environmental concern, tliis reaction is too 

Specific heat of vapor at constant pressure 0.149 Btu7(lb-°F) at 77°F 37 

Elemental sulfur exhibits complicated allotropy, that is, it exists in many modifications.The stable, prismatic crystal form at room temperature, o-S or orthorhombic sulfur, is built up of stacks of Sg rings (Section 3.4). If heated quickly, it melts at 112.8 °C. If it is heated slowly, however, it changes to needlelike crystals of /3-S or monoclinic sulfur, which is the stable form above 95.5 °C and which melts at 119 °C. Both /3-S and the yellow mobile melt (below 160 °C) are composed exclusively of Sg rings. Solids containing S7, Sg, Sio, S12, and other rings are known, but all slowly revert to Sg below 160 °C. 

As noted in Section 8.5, there are two important complications in the conversion of SO2 to liquid H2SO4 the oxidation of SO2 is generally slow and must be catalyzed, and the direct reaction of SO3 with water tends to produce intractable aerosols (mists) of H2SO4. The lead chamber process, which dates back to 1746, employs nitrogen oxides as the catalyst the intermediate HO—SO2—O—NO, or nitrosylsulfuric acid, is easily 

At present, almost all sulfuric acid is made by the contact process, which has been in use since 1831. The first step is exothermic air oxidation of SO2 catalyzed by vanadium pentoxide (V2O5) or platinum (reaction 10.5). The yield of SO3 is limited on the first pass to some 60% because the temperature rises to 600 °C or more usually, three more passes over the catalyst are made, and the yield can be increased to 98%. The SO3 vapor is then absorbed into 100% H2SO4 (reaction 10.6), and water is added to the resulting mixture of disulfuric (H2S2O7) and sulfuric acids (known as oleum) until the H2S2O7 is all hydrolyzed to H2SO4 (reaction 10.7). This obviates the aerosol problem. 

There are several sources of sulfur. Elemental sulfur is naturally occurring and can be mined by a process invented in the late 19 century by Herman Frasch. The Frasch process takes advantage of the relatively low melting point of sulfur at 115 C. Superheated water at 168 °C is pumped through pipes inserted into a well and molten sulfur is pumped from the well [4]. 

Another source is pyrite. Pyrite is iron sulfide (FeS2 . Pyrite is also known as fool s gold because of its visual resemblance to the precious metal. With 

Fundamentals of Industrial Chemistry- Pharmaceuticals, Polymers, and Business, First Edition. John A. lyrell. 2014 John Wiley Sons, Inc. Published 2014 by John Wiley Sons, Inc. 

A major source of sulfur is refinery and natural gas streams. This is done by the Claus process which was discovered more than 100 years ago and has been used by the natural gas and refinery industries for 50 years. In the Claus process, hydrogen sulfide from the gas stream is converted to elemental sulfur. Air is introduced into a furnace to oxidize about one-third of the hydrogen sulfide to sulfur dioxide. In the next stage, the reaction furnace, unconverted hydrogen sulfide reacts with the sulfur dioxide to form elemental sulfur. The Claus process generally produces an overall recovery of sulfur of 95-97%, but several modifications have been invented and sulfur recoveries of 99.9% are now achievable [6]. The chemistry is represented hy the following reactions the equilibrium to form elemental sulfur is favored at lower temperatures. 

The population of the U.S. is around 300 million people, so this is equivalent to each and every person in the United States making 0.1 metric tons each year. A metric ton is 1,000 kg or 2,240 pounds (not to be confused with a U.S. ton which is 2,000 pounds) so this is equivalent to each person making 

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Product removal during reaction. Sometimes the equilibrium conversion can be increased by removing the product (or one of the products) continuously from the reactor as the reaction progresses, e.g., by allowing it to vaporize from a liquid-phase reactor. Another way is to carry out the reaction in stages with intermediate separation of the products. As an example of intermediate separation, consider the production of sulfuric acid as illustrated in Fig. 2.4. Sulfur dioxide is oxidized to sulfur trioxide ... 

Intermediate separation followed by further reaction is clearly most appropriate when the intermediate separation is straightforward, as in the case of sulfuric acid production. 

Catalytic gas-phase reactions play an important role in many bulk chemical processes, such as in the production of methanol, ammonia, sulfuric acid, and nitric acid. In most processes, the effective area of the catalyst is critically important. Since these reactions take place at surfaces through processes of adsorption and desorption, any alteration of surface area naturally causes a change in the rate of reaction. Industrial catalysts are usually supported on porous materials, since this results in a much larger active area per unit of reactor volume. 

Example 2.5 tert-Butyl hydrogen sulfate is required as an intermediate in a reaction sequence. This can be produced by the reaction between isobutylene and moderately concentrated sulfuric acid ... 

Laboratory studies indicate that the reactor yield is a maximum when the concentration of sulfuric acid is maintained at 63 percent. ... 

However, the laboratory data seem to indicate that a constant concentration in the reactor to maintain 63 percent sulfuric acid would be beneficial. Careful temperature control is also important. These two factors would suggest that a continuous well-mixed reactor is appropriate. There is a conflict. How can a well-defined residence time be maintained and simultaneously a constant concentration of sulfuric acid be maintained ... 

Using a batch reactor, a constant concentration of sulfuric acid can be maintained by adding concentrated sulfuric acid as the reaction progresses, i.e., semi-batch operation. Good temperature control of such systems can be maintained, as we shall discuss later. 

In these methods, the sulfur oxides produced during combustion are, before detection, either converted into sulfuric acid by bubbling in a hydrogen peroxide-water solution or converted into sulfates. 

The main justification for diesel fuel desulfurization is related to particulate emissions which are subject to very strict rules. Part of the sulfur is transformed first into SO3, then into hydrated sulfuric acid on the filter designed to collect the particulates. Figure 5.21 gives an estimate of the variation of the particulate weights as a function of sulfur content of diesel fuel for heavy vehicles. The effect is greater when the test cycle contains more high temperature operating phases which favor the transformation of SO2 to SO3. This is particularly noticeable in the standard cycle used in Europe (ECE R49). 

Sulfonic acids can come from the sulfonation of oil cuts from white oil production by sulfuric acid treatment. Sodium salts of alkylaromatic sulfonic acids are compounds whose aliphatic chains contain around 20 carbon atoms. The aromatic ring compounds are mixtures of benzene and naphthalene rings. 

Carbonizable substances (paraffin) NFT 60-134 ASTM D 612 Coloration after treatment in concentrated sulfuric acid... 

Sulfated ash in lubricating oils in greases NF T 60-143 ISO 3987 ASTM D 874 NF T 60-144 ASTM D 128 Weight of residue after treatment of the ash by sulfuric acid and calcination As above... 

As mentioned in Section IX-2A, binary systems are more complicated since the composition of the nuclei differ from that of the bulk. In the case of sulfuric acid and water vapor mixtures only some 10 ° molecules of sulfuric acid are needed for water oplet nucleation that may occur at less than 100% relative humidity [38]. A rather different effect is that of passivation of water nuclei by long-chain alcohols [66] (which would inhibit condensation note Section IV-6). A recent theoretical treatment by Bar-Ziv and Safran [67] of the effect of surface active monolayers, such as alcohols, on surface nucleation of ice shows the link between the inhibition of subcooling (enhanced nucleation) and the strength of the interaction between the monolayer and water. 

A new dimension to acid-base systems has been developed with the use of zeolites. As illustrated in Fig. XVIII-21, the alumino-silicate faujasite has an open structure of interconnected cavities. By exchanging for alkali metal (or NH4 and then driving off ammonia), acid zeolites can be obtained whose acidity is comparable to that of sulfuric acid and having excellent catalytic properties (see Section XVIII-9D). Using spectral shifts, zeolites can be put on a relative acidity scale [195]. An important added feature is that the size of the channels and cavities, which can be controlled, gives selectivity in that only... 

Raduge C, Pfiumio V and Shen Y R 1997 Surface vibrational spectroscopy of sulfuric acid-water mixtures at the liquid-vapor interface Chem. Phys. Lett. 274 140... 

Nishihara C and Nozoye H 1995 influence of underpotentiai deposition of copper with submonolayer coverage on hydrogen adsorption at the stepped surfaces Pt(955), Pt(322) and Pt(544) in sulfuric acid solution J. Electroanal. Chem. 396 139-42... 

Ikemiya N, Miyaoka S and Hara S 1994 Observation of the Cu(1 1) adlayer on Au(111) in a sulfuric acid solution using atomic force microscopy Surf. Sc/. 311 L641-8... 

Toney M F, Howard J N, Richer J, Borges G L, Gordon J G, Melroy O R, Yee D and Sorenson L B 1995 Electrochemical deposition of copper on a gold electrode in sulfuric acid Resolution of the interfacial structure Phys. Rev. Lett. 75 4472-5... 

Sulfur is a component of black gunpowder, and is used in the vulcanization of natural rubber and a fungicide. It is also used extensively in making phosphatic fertilizers. A tremendous tonnage is used to produce sulfuric acid, the most important manufactured chemical. 

Lead is a bluish-white metal of bright luster, is very soft, highly malleable, ductile, and a poor conductor of electricity. It is very resistant to corrosion lead pipes bearing the insignia of Roman emperors, used as drains from the baths, are still in service. It is used in containers for corrosive liquids (such as sulfuric acid) and may be toughened by the addition of a small percentage of antimony or other metals. 

Selenium is found in a few rare minerals such as crooksite and clausthalite. In years past it has been obtained from flue dusts remaining from processing copper sulfide ores, but the anode metal from electrolytic copper refineries now provide the source of most of the world s selenium. Selenium is recovered by roasting the muds with soda or sulfuric acid, or by smelting them with soda and niter. 

Technetium is a silvery-gray metal that tarnishes slowly in moist air. The common oxidation states of technetium are +7, +5, and +4. Under oxidizing conditions technetium (Vll) will exist as the pertechnetate ion, TcOr-. The chemistry of technetium is said to be similar to that of rhenium. Technetium dissolves in nitric acid, aqua regia, and cone, sulfuric acid, but is not soluble in hydrochloric acid of any strength. The element is a remarkable corrosion inhibitor for steel. The metal is an excellent superconductor at IIK and below. 

The element is a steel-white metal, it does not tarnish in air, and it is the least dense and lowest melting of the platinum group of metals. When annealed, it is soft and ductile cold-working greatly increases its strength and hardness. Palladium is attacked by nitric and sulfuric acid. 

Tellurium improves the machinability of copper and stainless steel, and its addition to lead decreases the corrosive action of sulfuric acid on lead and improves its strength and hardness. Tellurium is used as a basic ingredient in blasting caps, and is added to cast iron for chill control. Tellurium is used in ceramics. Bismuth telluride has been used in thermoelectric devices. 

In the finely divided state platinum is an excellent catalyst, having long been used in the contact process for producing sulfuric acid. It is also used as a catalyst in cracking petroleum products. Much interest exists in using platinum as a catalyst in fuel cells and in antipollution devices for automobiles. 

Thallium occurs in crooksite, lorandite, and hutchinsonite. It is also present in pyrites and is recovered from the roasting of this ore in connection with the production of sulfuric acid. It is also obtained from the smelting of lead and zinc ores. Extraction is somewhat complex and depends on the source of the thallium. Manganese nodules, found on the ocean floor, contain thallium. 

Until the late 1950s chemists generally considered mineral acids, such as sulfuric, nitric, perchloric, and hydrofluoric acids, to be the strongest acid systems in existence. This has changed considerably as extremely strong acid systems—many billions or even trillions of times stronger than sulfuric acid—have been discovered. 

In the 1960s Gillespie suggested calling protic acids stronger than 100% sulfuric acid superacids. This arbitrary but most useful definition is now generally accepted. It should be mentioned, however, that... 

During my Cleveland years, I also continued and extended my studies in nitration, which I started in the early 1950s in Hungary. Conventional nitration of aromatic compounds uses mixed acid (mixture of nitric acid and sulfuric acid). The water formed in the reaetion dilutes the acid, and spent aeid disposal is beeoming a serious environ-... 

To solve some of the environmental problems of mixed-acid nitration, we were able to replaee sulfuric acid with solid superacid catalysts. This allowed us to develop a novel, clean, azeotropic nitration of aromatics with nitric acid over solid perfluorinated sulfonic acid catalysts (Nafion-H). The water formed is continuously azeotroped off by an excess of aromatics, thus preventing dilution of acid. Because the disposal of spent acids of nitration represents a serious environmental problem, the use of solid aeid eatalysts is a significant improvement. 

To be able to prepare and study these elusive species in stable form, acids billions of times stronger than concentrated sulfuric acid were needed (so called superacids). Some substituted carbocations, however, are remarkably stable and are even present in nature. You may be surprised to learn that the fine red wine we drank tonight contained carbocations which are responsible for the red color of this natural 12% or so alcoholic solution. I hope you enjoyed it as much as I did. 

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