Aluminium sulfateAluminium sulfate is a chemical compound with the formula Al2(SO4)3. It is soluble in water and is mainly used as a flocculating agent in the purification of drinking water[3][4] and waste water treatment plants, and also in paper manufacturing.

Aluminium sulfate is sometimes referred to as a type of alum. Alums are double sulfate salts, with the formula AM(SO4)2·12H 2O, where A is a monovalent cation such as potassium or ammonium and M is a trivalent metal ion such as aluminium.[5] The anhydrous form occurs naturally as a rare mineral millosevichite, found e.g. in volcanic environments and on burning coal-mining waste dumps. Aluminium sulfate is rarely, if ever, encountered as the anhydrous salt. It forms a number of different hydrates, of which the hexadecahydrate Al2(SO4)3•16H2O and octadecahydrate Al2(SO4)3•18H2O are the most common. The heptadecahydrate, whose formula can be written as [Al(H2O)6]2(SO4)3•5H2O, occurs naturally as the mineral alunogen.

Aluminium sulfate may be made by adding aluminium hydroxide, Al(OH)3, to sulfuric acid, H2SO4:2 Al(OH)3 + 3 H2SO4 → Al2(SO4)3+6H2Oor by heating aluminum metal in a sulfuric acid solution:2 Al(s) + 3 H2SO4 → Al2(SO4)3 + 3 H2 (g)

UsesAluminium sulfate is used in water purification and as a mordant in dyeing and printing textiles. In water purification, it causes impurities to coagulate into larger particles and then settle to the bottom of the container (or be filtered out) more easily. This process is called coagulation or flocculation. Research suggests that in Australia, aluminium sulfate used this way in drinking water treatment is the primary source of hydrogen sulfide gas in sanitary sewer systems.[6] Improper and excess application polluted the water supply of Camelford in Cornwall.

When dissolved in a large amount of neutral or slightly alkaline water, aluminium sulfate produces a gelatinous precipitate of aluminium hydroxide, Al(OH)3. In dyeing and printing cloth, the gelatinous precipitate helps the dye adhere to the clothing fibers by rendering the pigment insoluble.

Aluminium sulfate is sometimes used to reduce the pH of garden soil, as it hydrolyzes to form the aluminium hydroxide precipitate and a dilute sulfuric acid solution. An example of what changing the pH level of soil can do to plants is visible when looking at Hydrangea macrophylla. The gardener can add aluminium sulfate to the soil to reduce the pH which in turn will result in the flowers of the Hydrangea turning a different color (blue). The aluminium is what makes the flowers blue; at a higher pH, the aluminium is not available to the plant. Thus, both the aluminium and sulfur keep the plants blue.

Aluminium potassium sulfate and another form of alum, aluminium ammonium sulfate, are the active ingredients in some antiperspirants; however, beginning in 2005 the US Food and Drug Administration no longer recognized it as a wetness reducer. Despite this, several countries, primarily in Asia, still use the widely available and cheap alum sulfate as a very effective cure for a medical condition known as Hyperhydrosis.

Aluminium potassium sulfate is usually found in baking powder.

In the construction industry, it is used as waterproofing agent and accelerator in concrete. Another use is a foaming agent in fire fighting foam.

It is also used in styptic pencils, and pain relief from stings and bites.[medical citation needed]

It can also be very effective as a molluscicide, killing spanish slugs.

It is used in dentistry (especially in gingival retraction cords) because of its astringent and hemostatic properties

Calcium hypochlorite

Uses

Calcium hypochlorite is an inorganic compound with formula Ca(ClO)2. As a mixture with lime and calcium chloride, it is marketed as chlorine powder or bleach powder for water treatment and as a bleaching agent.[1] This compound is relatively stable and has greater available chlorine than sodium hypochlorite (liquid bleach).[2] It is a white solid, although commercial samples appear yellow. It strongly smells of chlorine, owing to its slow decomposition in moist air. It is not highly soluble in water and is more preferably used in soft to medium-hard water. It has two forms: dry and hydrated.

SanitationCalcium hypochlorite is commonly used to sanitize public swimming pools and disinfect drinking water. Generally the commercial substance is sold with a purity of a 68% (with other additives and contaminants varying based upon the product's intended purpose). For instance as a swimming pool chemical it is often mixed with cyanuric acid stabilizers and anti-scaling agents (in order to reduce the loss of chlorine from ultraviolet radiation and to prevent calcium hardening). Calcium hypochlorite is also used in kitchens to disinfect surfaces and equipment.[3] Other common uses include bathroom cleansers, household disinfectant sprays, algaecides, herbicides, and laundry detergents.Organic chemistryCalcium hypochlorite is a general oxidizing agent and therefore finds some use in organic chemistry.[4] For instance the compound is used to cleave glycols, α-hydroxy carboxylic acids and keto acids to yield fragmented aldehydes or carboxylic acids.[5] Calcium hypochlorite can also be used in the haloform reaction to manufacture chloroform.

PropertiesCalcium hypochlorite reacts with carbon dioxide to form calcium carbonate and release dichlorine monoxide:

Ca(ClO)2 + CO2 → CaCO3 + Cl2O↑A calcium hypochlorite solution is basic. This basicity is due to the hydrolysis performed by the hypochlorite ion, as hypochlorous acid is weak, but calcium hydroxide is a strong base. As a result, the hypochlorite ion is a strong conjugate base, and the calcium ion is a weak conjugate acid:

ClO− + H2O → HClO + Oh−Similarly, calcium hypochlorite reacts with hydrochloric acid to form calcium chloride, water and chlorine:

Ca(OCl)2 + 4 HCl → CaCl2 + 2 H2O + 2 Cl2

ProductionCalcium oxychloride is produced industrially by treating lime

(Ca(OH)2) with chlorine gas. The reaction can be conducted in stages to

give various compositions, each with different concentration of calcium

hypochlorite, together with unconverted lime and calcium chloride. The

full conversion is shown[1]

2 Cl2 + 2 Ca(OH)2 → Ca(OCl)2 + CaCl2 + 2 H 2OBleaching powder is not a simple mixture of calcium hypochlorite,

calcium chloride, and calcium hydroxide. Instead, it is a mixture

consisting principally of calcium hypochlorite Ca(OCl)2, dibasic

calcium hypochlorite, Ca3(OCl)2(OH)4, and dibasic calcium chloride,

Ca3Cl2(OH)4.[7] It is made from slightly moist slaked lime.

SafetyCalcium hypochlorite is stored dry and cold, away from any organic

material and metals. The hydrated form is safer to handle.

Sulfuric acidSulfuric acid (alternative spelling sulphuric acid) is a highly corrosive strong mineral acid with the molecular formula H2SO4 and molecular weight 98.079 g/mol. It is a pungent-ethereal, colorless to slightly yellow viscous liquid that is soluble in water at all concentrations.[6] Sometimes, it is dyed dark brown during production to alert people to its hazards.[7] The historical name of this acid is oil of vitriol.[8]Sulfuric acid is a diprotic acid and shows different properties depending upon its concentration. Its corrosiveness on other materials, like metals, living tissues or even stones, can be mainly ascribed to its strong acidic nature and, if concentrated, strong dehydrating and oxidizing properties. Sulfuric acid at a high concentration can cause very serious damage upon contact, since not only does it cause chemical burns via hydrolysis, but also secondary thermal burns through dehydration.[9][10] It can lead to permanent blindness if splashed onto eyes and irreversible damage if swallowed.[9] Accordingly, safety precautions should be strictly observed when handling it. Moreover, it is hygroscopic, readily absorbing water vapour from the air.[6]Sulfuric acid has a wide range of applications including in domestic acidic drain cleaners,[11] as an electrolyte in lead-acid batteries and in various cleaning agents. It is also a central substance in the chemical industry. Principal uses include mineral processing, fertilizer manufacturing, oil refining, wastewater processing, and chemical synthesis. It is widely produced with different methods, such as contact process, wet sulfuric acid process, lead chamber process and some other methods.

UsesSulfuric acid is a very important commodity chemical, and indeed, a nation's sulfuric acid production is a good indicator of its industrial strength.[27] World production in 2004 was about 180 million tonnes, 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%.[28] 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 pigments and include paints, enamels, 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.

The study of vitriol, a category of glassy minerals from which the acid can be derived, began in ancient times. Sumerians had a list of types of vitriol that they classified according to the substances' color. Some of the earliest discussions on the origin and properties of vitriol is 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.Persian alchemists Jābir ibn Hayyān (c. 721 – c. 815 AD, also known as Geber), Razi (865 – 925 AD), and Jamal Din al-Watwat (d. 1318, wrote the book Mabāhij al-fikar wa-manāhij 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 because it was prepared by roasting "green vitriol" (iron (II) sulfate) in an iron retort. There are references to it in the works of Vincent of Beauvais and in the Compositum de Compositis ascribed to Saint 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 seventeenth century, the German-Dutch chemist Johann Glauber prepared sulfuric acid by burning sulfur together with saltpeter (potassium nitrate, KNO3), in the presence of steam. As saltpeter decomposes, it oxidizes the sulfur to SO3, 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 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.[2]

Hydrochloric acidHydrochloric acid is a clear, colorless, highly pungent solution of hydrogen chloride (HCl) in water. It is a highly corrosive, strong mineral acid with many industrial uses. Hydrochloric acid is found naturally in gastric acid. When it reacts with an organic base it forms a hydrochloride salt.

It was historically called acidum salis, muriatic acid, and spirits of salt because it was produced from rock salt and green vitriol (by Basilius Valentinus in the 15th century) and later from the chemically similar common salt and sulfuric acid (by Johann Rudolph Glauber in the 17th century). Free hydrochloric acid was first formally described in the 16th century by Libavius. Later, it was used by chemists such as Glauber, Priestley, and Davy in their scientific research.

With major production starting in the Industrial Revolution, hydrochloric acid is used in the chemical industry as a chemical reagent in the large-scale production of vinyl chloride for PVC plastic, and MDI/TDI for polyurethane. It has numerous smaller-scale applications, including household cleaning, production of gelatin and other food additives, descaling, and leather processing. About 20 million tonnes of hydrochloric acid are produced worldwide annually.

a mixture consisting of hydrochloric and nitric acids, prepared by dissolving sal ammoniac in nitric acid, was described in the works of Pseudo-Geber, a 13th-century European alchemist. Other references suggest that the first mention of aqua regia is in Byzantine manuscripts dating to the end of the 13th century.Free hydrochloric acid was first formally described in the 16th century by Libavius, who prepared it by heating salt in clay crucibles. Other authors claim that pure hydrochloric acid was first discovered by the German Benedictine monk Basil Valentine in the 15th century, when he heated common salt and green vitriol, whereas others argue that there is no clear reference to the preparation of pure hydrochloric acid until the end of the 16th century.In the 17th century, Johann Rudolf Glauber from Karlstadt am Main, Germany used sodium chloride salt and sulfuric acid for the preparation of sodium sulfate in the Mannheim process, releasing hydrogen chloride gas. Joseph Priestley of Leeds, England prepared pure hydrogen chloride in 1772, and by 1808 Humphry Davy of Penzance, England had proved that the chemical composition included hydrogen and chlorine.

History

During the Industrial Revolution in Europe, demand for alkaline substances increased. A new industrial process developed by Nicolas Leblanc of Issoundun, France enabled cheap large-scale production of sodium carbonate (soda ash). In this Leblanc process, common salt is converted to soda ash, using sulfuric acid, limestone, and coal, releasing hydrogen chloride as a by-product. Until the British Alkali Act 1863 and similar legislation in other countries, the excess HCl was vented into the air. After the passage of the act, soda ash producers were obliged to absorb the waste gas in water, producing hydrochloric acid on an industrial scale.

In the 20th century, the Leblanc process was effectively replaced by the Solvay process without a hydrochloric acid by-product. Since hydrochloric acid was already fully settled as an important chemical in numerous applications, the commercial interest initiated other production methods, some of which are still used today. After the year 2000, hydrochloric acid is mostly made by absorbing by-product hydrogen chloride from industrial organic compounds production.

Since 1988, hydrochloric acid has been listed as a Table II precursor under the 1988 United Nations Convention Against Illicit Traffic in Narcotic Drugs and Psychotropic Substances because of its use in the production of heroin, cocaine, and methamphetamine.

Hydrochloric acid is a strong inorganic acid that is used in many industrial processes such as refining metal. The application often determines the required product quality.

Applications