Sulfuric acid

“ V = volume, in mL, of the sample test solutions 1 Fd = dilution factor for each sample test solution Fc = conversion factor to convert from anion to acid concentration: Fc = 1.021 for sulfate; Fc = 1.031 for phosphate EVALUATION OF METHOD: Laboratory testing with generated atmospheres of sulfuric acid mist yielded a collection efficiency of greater than 95% over the range 0.5 to 10 mg/m3 of H2SO4 on 0.45 μm pore size PTFE filters [4] . Greater than 95% recovery of sulfuric acid and phosphoric acid was found four weeks after sample collection. ”

“ Of all the products of chemical industry, sulfuric acid has always held the first place, and its importance increases yearly, since there is hardly a branch of manufacture in which it is not largely used. ”

“ The sulfur trioxid set free acts upon the organic matter in the powerful manner peculiar to it, and the potassium sulfate formed in the last reaction above unites with another molecule of sulfuric acid, and the same round of reactions is repeated continuously so long as there is an excess of free sulfuric acid present in the mixture. As the liquid becomes more concentrated with the continuation of the digestion, the boiling-point increases so that the effect is the same as heating under pressure. ”

“ Organic carbon, during this process, is converted chiefly into carbon dioxid, but small quantities of formic, propionic, and butyric acids are also produced. Any organic sulfur which is present is converted into acid. No hydrogen or nitrogen is eliminated in a free state. While slight alkalinity is favorable to the development of this bacterium, yet it may be propagated in a feeble sulfuric acid solution when the acid is less than one per cent. ”

“ Chlorosulfonic acid fumes in the air, because reaction with water forms sulfuric acid and hydrochloric acid.
ClSO2OH + H2O = H2SO4 + HCl
This material was not used by the United States since oleum was found superior.
Oleum. Oleum is a solution of 20 to 30 per cent sulfur trioxide (SO3) in concentrated sulfuric acid. It has been used by the Germans to produce clouds on land and sea, by its contact with quicklime, and by the Americans for screening tanks and aeroplanes. Sulfur trioxide has been found to be superior as a shell filling. ”

“ IN a 5-l. round-bottom flask, fitted with a mechanical stirrer, are placed 680 g. of sodium dichromate, 1500 cc. of water, and 230 g. of p-nitrotoluene. Stirring is started, and 1700 g. of concentrated sulfuric acid are allowed to flow in during about thirty minutes. The heat of dilution of the sulfuric acid will cause the nitrotoluene to melt, and rapid oxidation will soon take place. The last half of the sulfuric acid must be added gradually, in order to prevent too violent a reaction. Since a small amount of nitrotoluene is volatilized, it is advisable to carry on this work under a hood. ”

“ Then add 1 cc. of strong nitric acid and heat till red fumes are given off. Freshly ignited magnesia in the proportion of 0.5 gram for each cc. of sulfuric and nitric acid previously used is now stirred into the mass and the whole ignited at a dull red heat. This is best done in a gas-muffle. When cool, moisten the ash with nitric acid and gently re-ignite, repeating this treatment till the carbon [12] is entirely consumed. Treat the residue with 8 or 10 drops of strong sulfuric acid, heat till fumes are given off, cool, boil with water, dilute to about 100 cc. ”

“ It is prepared on the industrial scale for the manufacture of sulphuric acid, for the preparation of sodium sulphate by the Hargreaves process, and for use as a bleaching-disinfecting agent and as a preservative. When compressed it is also used largely as a refrigerating agent, and in virtue of its property of neither burning nor supporting combustion it is also used as a fire extinct or. The solution of the gas in water is used under the name of sulphurous acid. The free acid has not been isolated, since on evaporation the solution gradually loses sulphur dioxide. ”

“ The main action of sulphuric acid, so long associated with the alkali process, has made enormous strides during the present century, but is still, in the main, the original process of causing sulphur dioxide in presence of water to absorb the oxygen of the air through68 nitric oxide. But the saving of the oxides of nitrogen through the invention of a sulphuric acid power by Gay-Lussac, known by his name, and the re-utilization of these oxides in the “Glover” power, invented by John Glover, of Newcastle, have greatly lessened the cost of the acid. ”

“ The greater number of physiological and hygienic experts agree that the fumes of burning sulfur, commonly known as sulfurous acid, are injurious to health. It has been shown by researches in the Bureau of Chemistry that sulfurous acid or sulfites have a specific influence upon the red corpuscles of the blood, tending to diminish them very largely in relative numbers. ”

“ The general characters of sulphuric acid are as follows:—When pure, it is a colourless, or, when impure, a dark brown to black, oily liquid, without odour at common temperatures, of an exceedingly acid taste, charring most organic tissues rapidly, and, if mixed with water, evolving much heat. If 4 parts of the strong acid are mixed with 1 part of water at 0°, the mixture rises to a heat of 100°; a still greater heat is evolved by mixing 75 parts of acid with 27 of water. ”

“ Sulphur is also recovered in a very pure state from the “alkali waste ” of the Leblanc process, but this “recovered sulphur” is too expensive to be burned for the purpose in question. In the United Kingdom much gas sulphur is used for the manufacture of sulphuric acid, together with a limited quantity of Sicilian sulphur for the production of sulphuric acid free from arsenic.-A
much larger percentage of the sulphuric acid is made from pyrites, i.e. more or less pure disulphide of iron which occurs in arge quantities in many countries. ”

“ If the filtrate is examined, it is found to be strongly acid, since sulphuric acid has been liberated by the action of hydrogen sulphide on zinc sulphate: ZnSO4 + H2S → ZnS ↓ + H2SO4. Sulphuric acid is a strong acid, which is very highly ionized, much more so than the exceedingly weak acid hydrogen sulphide, and consequently, as the precipitation of zinc sulphide proceeds, the concentration of hydrogen-ion in the solution rapidly grows larger and larger. ”

“ Precipitation with sulphur dioxide and sulphuretted hydrogen proceeds much more rapidly, and has been adopted at many works. Sulphur dioxide, generated by burning sulphur, is forced into the solution under pressure, where it interacts with any free chlorine present to form hydrochloric and sulphuric acids. Sulphuretted hydrogen, obtained by treating iron sulphide or a coarse matte with dilute sulphuric acid, is forced in similarly. The gold is precipitated as the sulphide, together with any arsenic, antimony, copper, silver and lead which may be present. ”

“ Sulphurous Acid, H2SO3.—The reagent used may be regarded as a saturated solution of sulphur dioxide in water. It may be purchased, and keeps for a long time. It may be made by heating copper with sulphuric acid and passing the gas formed into water. The heat should be withdrawn when the gas is coming off freely. It is used as a reducing agent, and should not be diluted.
Sulphuric Acid, H2SO4. (Sp. gr. 1.84, containing 96 per cent. of real acid, H2SO4.) —This acid forms insoluble sulphates with salts of lead, strontium, and barium. ”

“ The action of diluted sulphuric acid on metals closely resembles that of dilute hydrochloric acid. Magnesium, aluminium, iron, zinc, nickel, cobalt, manganese, and cadmium dissolve, with evolution of hydrogen, in the cold acid, or when warmed. The action of hot and strong sulphuric acid is [Pg 59] altogether different; it acts as an oxidising agent, and is itself reduced to sulphur dioxide or even to sulphur. The following metals are attacked in this way:—copper, bismuth, mercury, silver, antimony, tin, and lead. Gold, platinum, and arsenic are not affected. ”

“ The presence of a salt of lead is detected by adding a few drops of sulphuric acid to the solution of nitrate of silver, which precipitates the lead as sulphate if present. It is, however, necessary to dilute the acid with a considerable quantity of water, and, if any precipitate forms, to allow it to subside previous to using it as a test for lead, as ordinary sulphuric acid is frequently contaminated with sulphate of lead, which is soluble in the strong, but not in dilute, acid. ”

“ SULPHURIC ACID, or Oil of Vitriol, H2SO4, perhaps the most important of all chemicals, both on account of the large quantities made in all industrial countries and of the multifarious uses to which it is put. It is not found in nature in the free state to any extent, and although enormous quantities of its salts, especially calcium and barium sulphate, are found in many localities, the free acid is never prepared from these salts, as it is more easily obtainable in another way, viz. by burning sulphur or a sulphide, and combining the sulphur dioxide thus formed with more oxygen (and water) . ”

“ Chemical Analysis.—Sulphonal is very stable, and is unaffected by boiling alkalies or by concentrated nitric or sulphuric acids. From its solution in concentrated sulphuric acid it may be recovered by dilution. It is easily recovered from the body after death, as its stability prevents its decomposition. It is isolated from organic matter by treatment with alcohol, evaporation, and extraction of the residue with hot water, evaporation and final extraction with ether. ”

“ Sulphuric acid, when well prepared, is a colourless and inodorous liquid, of an oily aspect, possessing a specific gravity, in its most concentrated state, of 1·842, when redistilled, but as found in commerce, of 1·845. It is eminently acid and corrosive, so that a single drop will communicate the power of reddening litmus to a gallon of water, and will produce an ulcer of the skin when allowed to remain upon it. If swallowed in its strongest state, in even a small quantity, it acts so furiously on the throat and stomach as to cause intolerable agony and speedy death. ”

“ It is also evolved from decaying animal matter containing albumen, such as white-of-egg, as well as from putrisable animal and vegetable substances, when in contact with a soluble sulphate, and is always one of the gases present in the air of drains and sewers. Sulphuretted hydrogen may be procured by the direct union of hydrogen and sulphur, as by passing hydrogen into boiling sulphur. But this method of procuring it is rarely, if ever, adopted. The much readier process of acting upon a metallic sulphide by an acid constitutes the means by which the chemist almost invariably obtains this gas. ”

“ When sulphides or mercaptans in glacial acetic acid solution are heated with permanganate, the resulting sulphonic acid compounds exhibit great similarity to compounds containing free carboxyl groups. The sulphonic acid group may also be directly introduced either by concentrated, or by fuming sulphuric acid, or by elimination of halogen by the action of sodium or silver sulphite on the halogen derivatives of the aliphatic compounds. ”

“ Sulphuric acid itself forms a compound with sodium sulphate, which is exactly like these double salts. It is formed with great ease when sodium sulphate is dissolved in sulphuric acid and the solution evaporated. On evaporation, crystals of the acid salt separate, Na2SO4 + H2SO4 = 2NaHSO4. This separates from hot solutions, whilst the crystallo-hydrate, NaHSO4,H2O, [10] separates from cold solutions. The crystals when exposed to damp air decompose into H2SO4, which deliquesces, and Na2SO4 (Graham, Rose) ; alcohol also extracts sulphuric acid from the acid salt. ”

“ It would be difficult to find another artificially-prepared substance which is so frequently applied in the arts as sulphuric acid. Where there are not works for its manufacture, the economical production of many other substances of great technical importance is impossible. In those localities which have arrived at a high technical activity the amount of sulphuric acid consumed is proportionally large; sulphuric acid, sodium carbonate, and lime are the most important of the artificially-prepared agents employed in factories. ”

“ When the sulphur has been completely burnt off, the residue (which consists chiefly of sand) is collected and weighed. In a separate portion the moisture and arsenic are determined; the amounts of [Pg 368] these are deducted from the loss in the first experiment. The difference, multiplied by 10, gives the percentage of sulphur.
WET METHODS.
Solution.—All sulphates, excepting those of lead, barium, strontium, and lime, are soluble in water or dilute acid. All sulphides, except cinnabar, are converted into sulphates by the action of nitric acid at a gentle heat ”

“ The second class of causes of contamination consists of chemicals. The most important chemical product is sulphuric acid. This used to be made from brimstone or native volcanic sulphur, which is virtually free from arsenic. But since about 1860 sulphuric acid has been more largely made from iron or copper pyrites. Pyrites-acid is always arsenical, but can, by suitable treatment, be easily freed from that impurity. For many purposes acid that has not been purified is employed. In the Leblanc process of manufacture the first step is the conversion of salt into sodium sulphate by sulphuric acid. ”