Inorganic chemistry

The inorganic chemistry (abbreviated AC) or inorganic chemistry is the chemistry of all -carbon compounds and some exceptions (see Inorganic substances ). A border area of organic chemistry, the organometallic compounds. While the Organic Chemistry uses this only as a tool or reagent, inorganic chemistry considers the coordination chemistry of metals.

Historically employed inorganic chemistry with substances that are not produced by organic life by life force. Since the synthesis of urea in 1828 by Friedrich Wöhler, in which the organic substance urea was prepared from the inorganic compound ammonium cyanate, the boundaries between substances blur from the inanimate ( the " inorganic " substances) and the living world ( the " organic " substances). To make living beings also manufactures a variety of inorganic materials, while in the laboratory almost all organic materials can be produced now. Nevertheless, the modern distinction is still meaningful, since the reaction mechanisms and fabric structures in the inorganic and organic differ widely.

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History of inorganic chemistry

Many inorganic substances and some inorganic nutrient cycling were already known in antiquity. The metal extraction from ores (gold, silver, copper, tin, lead, iron, mercury), the pottery industry, the glass preparation (Egypt), the production of porcelain (China), the mineral colors ( white lead, red lead, verdigris, vermilion, orpiment ), the sulfur for smoking, the lime ( for mortar for residential), salts such as sodium chloride ( for food preparation ), soda ( for the manufacture of glass and soap), nitric ( as a remedy ), alum ( tanneries ).

In alchemical era, in the 13th century, production methods for recovering sulfuric acid, dilute hydrochloric acid, nitric acid ( aqua fortis to the dissolution of silver from gold-silver alloys) and aqua regia ( hydrochloric and nitric acid to dissolve gold) by Arab alchemists ( Pseudo-Geber were fonts ) are known. The manufacturing process of acids were significantly improved later by Johann Rudolph Glauber in 1650, still he developed a method for obtaining fuming hydrochloric acid.

Robert Boyle described in his major work The Sceptical Chemist in rejection of the Aristotelian theories of alchemy a turn to experimental research and conclusions on the basis of experiments. Significant was his thesis that the chemical elements from swallowed divisible, same, small atoms, chemical compounds are composed of a variety of small, different elements.

Georg Ernst Stahl and Johann Joachim Becher developed in 1700 the theory of phlogiston. With this theory, 80 years later it turned out to be incorrect, combustion processes, oxidations and reductions as well as the fermentation could be chemically interpreted. Cause of the misinterpretation of the phlogiston theory was then still unknown substance (oxygen) in the air.

Joseph Priestley made ​​studies with the air and realized that in the air a substance is present, respiration processes and favors the oxidation of metals to metal oxides. From heating mercury (II ) oxide Priestley was the substance - of Respiratory and combustion processes promotes - gaseous win and also determine the level of this substance in the air. Only Antoine Laurent de Lavoisier drew from the findings of Priestley concluded that this newly discovered substance (oxygen) must be a member. The theory of the elements of Boyle was confirmed by Lavoisier's conclusions and considers the elements and a plurality of identical, indivisible atoms. A chemical compound contains several different elements. As pure metals, the elements gold, silver, copper, tin, lead, zinc, and the non-metallic elements phosphorus, sulfur, carbon, oxygen, nitrogen, classified. Lavoisier also recognized that any material implementation of the sum of the weights of starting materials and end products remains the same ( mass conservation law ). The old alchemical names of inorganic materials have been modified by a rational number with the respective elementary components of the mixture. The oxidation theory by Lavoisier represented a major breakthrough in chemistry, the following chemists now had to find the pure elements.

Almost at the same time was the discovery of electricity by Luigi Galvani and Alessandro Volta. Through this voltaic pile to let the water decompose oxygen and hydrogen gas in the elements and determine the composition of water by volume and weight determination of the two gases accurately.

Humphry Davy was deposited as new elements with the voltaic pile sodium and potassium. John Dalton presented a first - still very inaccurate - together table of atomic weights for elements Jöns Jacob Berzelius devised a method for the determination of very precise atomic weights of metals and other elements, and also developed the formula language to the one or two Latin letters for the elements and related the relative atomic weights of oxygen as a reference point. Amedeo Avogadro hypothesized that in equal-sized rooms and at the same temperature always the same number of particles of a gas must be present.

In the following years the search for new chemical elements, the determination of their exact relative atomic weights and their characterization were by reactions with other substances to the most important tasks of the inorganic chemist.

Joseph Louis Gay -Lussac developed the titration and was able to determine the quantitative content of individual elements in an inorganic compound. Later the Electrogravimetric deposition for the content determination of mineral samples was used. Robert Bunsen improved the method of power generation by developing a zinc -carbon battery. In his lab, the new elements magnesium, chromium and strontium could be won. Developed by Bunsen spectral analysis led to the discovery of the elements cesium and rubidium, and later by William Ramsay also of helium.

Lothar Meyer and Dmitri Mendeleev sorted the chemical elements according to atomic weight and binding capacity in a periodic table. This facilitates the predictions for the chemical behavior of elements could be made and as yet unknown elements are visited in the system.

Svante Arrhenius, Jacobus Henricus van't Hoff and Wilhelm Ostwald realized that the molecules of acids, bases and salts are present in aqueous solutions as ions. The discovery of the dissociation of salts and acids was the basis for important new insights ( eg, reaction mechanisms, kinetics ) and measurement methods (eg pH measurement, Conductometry ) in chemistry.

Inorganic substances

The inorganic materials of the elements and all links are counted traditionally do not contain carbon.

There are also some exceptions of carbon compounds that are constructed exactly like typical inorganic substances or are historically associated with the inorganic matter. These include hydrogen-free chalcogenides of carbon ( carbon monoxide, carbon dioxide, carbon disulfide ), the carbon dioxide and carbonates, carbides and the ionic cyanides, cyanates and thiocyanates. The hydrocyanic acid is considered as a limiting case and is treated in both the organic and inorganic chemistry. Although one would count traditionally used inorganic chemistry, it is seen as nitrile (organic material group ) of formic acid.

Inorganic chemistry textbooks are ordered by the chemical elements of the Periodic Table. In the textbooks the occurrence and recovery of the elements or compounds of elements from minerals, salts, aqueous solutions or gases are handled. Furthermore, important transformations of these elements with other elements are described.

Metals

Of the hundreds of elements of the periodic table are 76 % metals. As early as 3000-2000 BC won people from ore metals such as tin, copper, silver and iron. Metals were obtained by the high heating of mineral ores. With the exception of mercury, all metals at room temperature are fixed and can be liquefied by heating. The good formability of liquefied metals for the production of commodities is still used today on a large scale. Metal properties are the conductivity for heat and electricity.

Since the 19th century metals can be recovered by the electric current (electrolysis and electrolytic refining ). New metals - such as the aluminum and the alkali and alkaline earth metals - were discovered there. For many applications, light metals such as aluminum or titanium are needed so that airplanes, automobiles, trains, machines which do not have excessive energy consumption. Iron is the most important metal in the automotive industry due to the high hardness and temperature resistance. The surface of the iron tends under the influence of moisture on the formation of rust. In the early eighties of the last century showed many vehicles on a significant rust. Ten years later, many vehicles already had a rust protective zinc coating.

Metals are used as batteries and accumulators to generate electricity. In the low-cost carbon zinc batteries, the zinc is oxidized to zinc salt during power delivery. Other important batteries include nickel -metal hydride batteries ( wiederaufladbar! ), lithium batteries (very light battery ) or the low-cost lead- lead oxide batteries ( wiederaufladbar! ).

Alloys of metals may sometimes have better properties than the pure elements. The duralumin is a mixture of magnesium, copper and aluminum, it has a higher hardness than the pure aluminum. The Wood's metal is an alloy of bismuth, lead, cadmium and tin with a very low melting point, it is used for fusible shapes. Other significant metallic alloys are bronze ( copper and tin), brass ( copper and zinc ) and steel ( iron alloys with different admixtures ).

Some metals can combine with non-metals to crystal structure with new properties. The silicon combines with germanium, indium or arsenic. Such crystals are used as a semiconductor ( or light emitting diodes ) in the electronics. Other metals - such as the tantalum - find capacitors as a field of application in electronics.

Metals or metal ions are in the reactions in the gas phase or in a liquid used as catalysts, for example iron in the ammonia or aluminum ions in the synthesis of polyethylene.

Salts, minerals

The water is the most important material of inorganic chemistry, it has covalent, polarized bonds between the atoms and can have many inorganic salts dissolve well. The temperature range between the freezing and boiling point of water makes life possible on our planet by the solubility of inorganic and organic substances in liquid water.

Inorganic salts differ in their solubility in water. Due to the different solubility in water, salts can often be separated by filtration.

The mixture of two salts which are soluble in water - for example, barium chloride and sodium sulphate - can lead to the formation of a sparingly soluble salt ( barium sulfate). If the solubility of a salt low, it falls out.

Many metal cations form with sulfide anions in a solution sparingly soluble sulfides. By a proper choice of acids and bases can be enriched and specific groups of chemical elements determined as sulphide precipitation. In analytical chemistry which sulphide precipitation is a major division of transition metal cations. Even in rocks and minerals, metal cations are included. The metals in rocks are frequently in silicates and they are not soluble in water. In addition to very strong acids inorganic chemists use the Sodaufschluss to solve the ingredients of the rocks.

Concrete: silicates have a very great importance, for example, the Aluminiumsilkate, known as clay minerals. If we mix this clay with lime, the result is cement. When mixing gravel, stone gravel with cement mortar is obtained concrete. Almost all residential buildings in Germany A major part of concrete.

Porcelain: Another key is the kaolin. With quartz and feldspar to the clay by firing porcelain is converted.

Glass: If quartz sand heated by the addition of salt soda at 1000 ° C, the result is glass.

Poorly soluble salts have been and are used as pigments for the coloration of paints.

Inorganic salts are of great importance as a fertilizer. These salts are usually soluble in water. Sometimes in fertilization too high solubility is not always desirable. Ammonium sulfate, potassium chloride, and phosphate fertilizers ( less water soluble) increase the fertility of the soil considerably.

Acids and Bases

Very important inorganic acids are:

• Sulfuric acid

• Hydrochloric acid

• Nitric acid

• Phosphoric acid

Important inorganic bases are:

• Sodium hydroxide solution
• Ammonia

The inorganic acids and bases needed for the recovery of inorganic salts and organic substances. Sulfuric acid is quantitatively the most important link of the entire chemical industry. In contrast, inorganic acids metals are broken down into salts, and it forms hydrogen.

The knowledge of acids and bases has been significantly enhanced by the dissociation theory.

Gases

Many inorganic material reactions are associated with the development of gases. In water electrolysis evolve hydrogen and oxygen gas.

In the chlor-alkali electrolysis, the gases hydrogen and chlorine produced. These gases can react to the hydrogen chloride gas and forms with water containing hydrochloric acid.

Through the burning of sulfur in the air, the sulfur dioxide gas is evolved. Through an catalyst (contact method with vanadium oxide ) can react to sulfur trioxide two sulfur molecules with another oxygen atom. In water, the sulfur trioxide dissolves to form sulfuric acid.

Hydrogen sulfide can of pyrite ( FeS2 ) and hydrochloric acid are produced.

Carbon dioxide is produced by heating the lime burning of calcium carbonate for the production of cement. When hardening of the cement resumes carbon dioxide from the air.

From the atmospheric nitrogen and hydrogen gas, the ammonia gas can be produced by the Haber -Bosch process under high pressure and at 500 ° C.

The ammonia can be linked to nitric oxide, which reacts with more oxygen to form nitrogen dioxide by the Ostwald process with oxygen. Dissolved in water then forms nitric acid.

Oxygen, nitrogen and argon can be obtained from the air by the Linde process. Growing economic interest for the separation of individual gases also gain method to gas separation by means of very fine-pored membranes ( membrane gas ).

A very important field of study of gases in the air is the atmospheric chemistry.

Others

Inorganic cations can exist in different oxidation states as solid salts or in solution. This has the consequence that they also can have many different anions as counterions. In a solution particles can accumulate (ligands ) with ( eg, chloride, thiocyanate ) or without negative charge ( for example, ammonia or water by free electron pairs ) on cations and form colored complexes. They form complexes with more - for steric reasons, often four to six - ligands on the cation, as the oxidation number pretending. The ions of the transition metals ( titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper ), having the d- electrons on the shell which form colored complexes with many ligands. The copper (II ) ion forms with ammonia the blue colored Kupfertetraminkomplex. In Prussian blue, the iron (III ) hexacyanoferrate, each iron ion is surrounded by six cyanide ions as ligands.

The ligand field theory describes the spatial coordination. With the magneto chemistry and about the color of the solution inorganic chemist can make statements about the coordination of such complexes. In Permanganatanion manganese has (VII ) ion four oxygen atoms as ligands. The well- colored complex of the potassium permanganate is used for quantitative determination in the titrimetry.

Organic acids such as EDTA ( quantitative determination of alkaline earth ions ) or tartaric acid or citric acid ( with copper (II) as Fehling's solution or Benedict's reagent for the determination of oxidizable sugars ) and dioxime ( dimethylglyoxime for nickel determination ) are suitable as often chromophoric ligands (specifically chelates ) for cations.

Inorganic reactions

In inorganic chemistry a variety of reactions play a role. The most important of which are the redox reactions and the acid -base reactions. These reactions are always equilibrium reactions, however, the balance is often very strong in these reactions on one side and there is a high reaction enthalpy. Thus, many reactions in the Inorganic and quickly achieve a high yield. In contrast, in the organic chemistry, many reactions slow equilibrium reactions, which do not always achieve high yields.

In redox reactions, electrons are transferred from one to the other reactants. Typical redox reactions are reactions of elements to form compounds. The redox reactions are known to react with oxygen to form oxides, the oxyhydrogen reaction of hydrogen and oxygen into water, and corrosion in the base metals (eg, iron ).

Acid -base reactions are reactions in which protons are transferred. The acid in this case indicates the base (also: liquor) from a proton. In acid -base reactions usually form water and a salt ( the best known example is the reaction of hydrochloric acid with sodium hydroxide to form sodium chloride and water). Since these reactions occur very rapidly and can be checked exactly with indicators, they play an important role in analytical chemistry.

In inorganic chemistry, the formation of insoluble salts or gaseous compounds is an important driving force for reactions, because this reaction products leave the balance and hence the reaction is complete in only one direction. So when poured together a barium chloride solution and abundant sodium sulfate solution in a precipitation reaction is very sparingly soluble barium sulphate is precipitated, and indeed so complete that after filtering off the barium sulfate no more barium ions can be detected in the remaining sodium chloride solution:

As an example of a directional equilibrium reaction due to escaping gases, the reaction of ammonium chloride, with sodium hydroxide solution to volatile ammonia:

Such reactions play in analytical chemistry also play an important role.

Various inorganic compounds may decompose at higher temperatures, by escaping gases. One example is the lime burning, where calcium carbonate from escaping carbon dioxide and calcium oxide remaining.

Branches of inorganic chemistry

• Chemistry of metals
• Chemistry of non-metals
• Complex chemistry including bioinorganic chemistry
• Solid State Chemistry
• Crystallography
• Structural Chemistry
• Organometallic Chemistry ( stands between inorganic and organic chemistry )
• Colloid Chemistry
• Atmospheric chemistry
• Mineral acids

Technical Applications

The inorganic chemistry is based on a variety of technical applications, for example,

• Semiconductor Research
• Mineralogy
• Metallurgy Production of iron and steel

Inorganic Chemistry in Schools and Universities

School

In the education of the students basics of atomic theory, the chemical behavior of elements, the oxidation numbers of the elements, the properties of inorganic salts ( color reactions, solubilities ), precipitation reactions, the ionic theory, acid -base reactions, determination of content gets in the field of inorganic chemistry by titration, redox reactions, electrolysis and important technical methods offered.

Study

In studying the independent scientific papers taught in inorganic chemistry. The chemistry student learns the detection reactions for cations and anions know from unknown samples. The placement of the inorganic analytical chemistry is divided into qualitative and quantitative analysis of inorganic substances. Furthermore, the representation of preparative inorganic materials being taught. The student learns to sharpen the powers of observation to work carefully and methodically to think combinatorially.