# zinc

properties
[ Ar ] 3 d 10 4 s 2
30 notes
General
Name , symbol , atomic number Zinc, Zn, 30
Element category Transition metals
Group , period , block 12 , 4 , d
Appearance bluish pale gray
CAS number 7440-66-6
EC number 231-175-3
ECHA InfoCard 100.028.341
ATC code
Mass fraction of the earth's envelope 0.012%
Atomic
Atomic mass 65.38 (2) u
Atomic radius (calculated) 135 (142) pm
Van der Waals radius 139 pm
Electron configuration [ Ar ] 3 d 10 4 s 2
1. Ionization energy 9.394 197 (6) eV 906.4 kJ / mol
2. Ionization energy 17th.96439 (25) eV1 733.3 kJ / mol
3. Ionization energy 39.72330 (12) eV3 832.71 kJ / mol
4. Ionization energy 59.573 (19) eV5 747.9 kJ / mol
5. Ionization energy 82.6 (9) eV7 970 kJ / mol
Physically
Physical state firmly
Crystal structure hexagonal
density 7.14 g / cm 3 (25 ° C )
Mohs hardness 2.5
magnetism diamagnetic ( Χ m = −1.6 10 −5 )
Melting point 692.68 K (419.53 ° C)
boiling point 1180 K (907 ° C)
Molar volume 9.16 10 −6 m 3 mol −1
Heat of evaporation 115 kJ / mol
Heat of fusion 7.4 kJ mol −1
Speed ​​of sound 3700 m s −1
Specific heat capacity 388 J kg −1 K −1
Electric conductivity 16.7 · 10 6 A · V −1 · m −1
Thermal conductivity 120 W m −1 K −1
Chemically
Oxidation states 2
Normal potential −0.7926 V (Zn 2+ + 2 e - → Zn)
Electronegativity 1.65 ( Pauling scale )
Isotopes
isotope NH t 1/2 ZA ZE (M eV ) ZP
64 notes 48.6  % Stable
65 notes {syn.} 244.06 d β + 1.352 65 Cu
66 notes 27.9% Stable
67 notes 4.1% Stable
68 notes 18.8% Stable
69 notes {syn.} 56.4 min β - 0.906 69 Ga
70 notes 0.6% Stable
For other isotopes see list of isotopes
NMR properties
Spin
quantum
number I
γ in
rad · T −1 · s −1
E r  ( 1 H) f L at
B = 4.7 T
in MHz
67 notes 5/2 1.677 · 10 7 0.000118 6.26
safety instructions
GHS hazard labeling from  Regulation (EC) No. 1272/2008 (CLP) , expanded if necessary

powder

danger

H and P phrases H: 250-260-410
P: 222-210-231 + 232-280-370 + 378-273
As far as possible and customary, SI units are used.
Unless otherwise noted, the data given apply to standard conditions .

Zinc is a chemical element with the element symbol Zn and the atomic number 30. Zinc is counted among the transition metals , but has a special position in it because its properties are more similar to the alkaline earth metals due to the closed d-shell . According to the outdated census, the zinc group is referred to as the 2nd  subgroup (analogous to the alkaline earth metals as the 2nd  main group ); according to the current IUPAC nomenclature, zinc forms group 12 with cadmium , mercury and copernicium, which is exclusively relevant in research bluish-white brittle metal and is used, among other things, for galvanizing iron and steel parts and for rain gutters. Zinc is essential for all living things and is a component of important enzymes . The name zinc comes from Zinke, Zind ("tooth, point"), because zinc solidifies in the form of a point.

## history

Zinc was already in use as an alloy component of brass in ancient times . However, zinc was not discovered and processed as an independent metal until the 14th century in India and brass from the 17th century. Galmei was smelted in the brass yard in Kassel , built in 1679 . In 1743 the first zinc smelter was opened in Bristol . Others emerged in Upper Silesia in the 19th century , e.g. B. Georg von Giesche or their successor company, in the Aachen - Liège area as well as in Upper Saxony and Westphalia . In the Ruhr area , the first huts were built in Mülheim an der Ruhr in 1845 and in Borbeck (now Essen) in 1847 .

## Occurrence

Zinc is a relatively common element on earth with a content of 0.0076% (or 76 ppm) in the earth's crust . If you order the elements by frequency, it is in 24th position. It's more common than copper or lead . Although zinc is rarely dignified before, but as a mineral usually recognized. So far, around 30 registered sites for native zinc are known.

Zinc is mainly found bound in ores . The most common ores that are most important for zinc production are zinc sulphide ores . These come naturally as either sphalerite or wurtzite and contain around 65% zinc. Another zinc ore is calamine, which means both smithsonite (also zinc spar ) ZnCO 3 (approx. 52% zinc) and willemite Zn 2 [SiO 4 ]. In addition, there are even rarer zinc minerals such as zincite (also red zinc ore ) ZnO (approx. 73% zinc), hemimorphite Zn 4 (OH) 2 [Si 2 O 7 ] (54% zinc), adamin Zn 2 (AsO 4 ) (OH ) (approx. 45% zinc), minrecordite CaZn [CO 3 ] 2 (approx. 29% zinc) and franklinite (Zn, Fe, Mn) (Fe 2 Mn 2 ) O 4 (16% zinc). In total, over 300 zinc minerals are currently (as of 2010) known.

Large deposits exist in North America (United States, Canada), Australia, the People's Republic of China and Kazakhstan. There were also zinc ore deposits in Germany, for example in Brilon , in the Eschweiler-Stolberg area in the Rhineland , on Rammelsberg in the Harz Mountains , Freiberg or near Ramsbeck in the Sauerland . Above ground you can find rare plants in these areas that grow particularly well on zinc-rich soils, such as the yellow calamine particle , which is named after the old name for the zinc ore, smithsonite ( calamine ).

## States with the greatest funding

Zinc Mine Rosh Pinah, Namibia
Zinc Mine Scorpion, Namibia

Zinc ores are mainly mined in the People's Republic of China , Australia , Peru , India , the United States , Mexico and Canada . In Europe some zinc mines are still active in Ireland , Poland , Finland , Bulgaria and Sweden . The total production of zinc amounted to 13.4 million tons in 2015, another 14 million tons were obtained from recycling . The most important company for the extraction of zinc is the Swiss Nyrstar .

Zinc ore production in thousands of tons (2017)
1  People's Republic of China 5,100 41,000
2  Peru 1,400 28,000
3  Australia 1,000 64,000
4th  United States 730 9,700
5  Mexico 680 20,000
6th  Kazakhstan 360 13,000
8th  Sweden 260 3,800

## Extraction and presentation

Zinc is mainly obtained from zinc sulfide ores. To use these, they must first be converted to zinc oxide. This is done by roasting in the air. In addition to the zinc oxide, large amounts of sulfur dioxide are produced , which can be further processed into sulfuric acid .

${\ displaystyle \ mathrm {2 \ ZnS \ + \ 3 \ O_ {2} \ \ longrightarrow 2 \ ZnO \ + \ 2 \ SO_ {2} \ uparrow}}$

If Smithsonite is used as a raw material, this can be done by burning with the release of carbon dioxide .

${\ displaystyle \ mathrm {ZnCO_ {3} \ \ longrightarrow \ ZnO \ + \ CO_ {2} \ uparrow}}$
Wet (electrochemical) and dry (metallurgical) extraction of zinc

Further processing can be done by two possible methods, the wet and the dry method. Today, only around 10% of the world's zinc produced is obtained using the dry process . The zinc oxide is mixed with finely ground coal and heated to 1100–1300 ° C in a fan shaft furnace (Imperial Smelting furnace). Carbon monoxide is initially formed . This then reduces the zinc oxide to metallic zinc. According to the Boudouard equilibrium , carbon monoxide is formed from the resulting carbon dioxide.

${\ displaystyle \ mathrm {ZnO \ + \ CO \ \ longrightarrow \ Zn \ uparrow + \ CO_ {2}}}$
Reduction of zinc
${\ displaystyle \ mathrm {CO_ {2} \ + \ C \ \ longrightarrow \ 2 \ CO}}$
Boudouard equilibrium

Since temperatures in the furnace are above the boiling point of zinc, the zinc escapes as vapor at the top of the furnace. Lead is now sprayed in there and the zinc condenses out.

The resulting raw zinc contains large amounts of impurities, especially lead, iron and cadmium . The raw zinc can be further purified by fractional distillation . In a first stage, the raw product is heated in such a way that only zinc and cadmium evaporate, while iron and lead remain. Cadmium and zinc can be separated from one another by condensation. Zinc condenses at higher temperatures and forms 99.99% pure zinc. Cadmium is more volatile and is collected in a different location than cadmium dust. As a by-product of the distillation, finely powdered zinc, known as zinc dust, is produced .

The wet method is used when cheaper electricity is available. For the process, the raw zinc oxide is dissolved in dilute sulfuric acid. Impurities in noble metals like cadmium are precipitated by zinc powder. Then the solution is using lead anodes and aluminum cathode electrolyzed . As with the dry process, 99.99% pure electrolytic zinc is produced at the cathode.

## properties

### Physical Properties

Zinc is a bluish-white, non-noble metal, which quite at room temperature and above 200 ° C brittle is. However, between 100 and 200 ° C it is quite ductile and can be easily deformed. Its break is silvery white. Zinc crystallizes in a hexagonal close packing of spheres . However, this is stretched perpendicular to the spherical layers, the distances between the zinc atoms differ slightly (in one layer 264.4 pm, between the layers 291.2 pm).

### Chemical properties

In the air, zinc forms a weather-resistant protective layer made of zinc oxide and carbonate (Zn 5 (OH) 6 (CO 3 ) 2 ). Therefore, despite its ignoble character, it is used as protection against corrosion ( galvanizing iron). Zinc dissolves in acids with the formation of zinc (II) salts and in alkalis with the formation of zincates , [Zn (OH) 4 ] 2− . An exception is zinc with a very high purity (99.999%), which does not react with acids. Almost without exception, zinc is present in its compounds in the + II oxidation state .

Chemically, zinc is one of the base metals ( redox potential −0.763 volts). This can be used, for example, to separate more noble metals from their salts by elemental reduction , as shown here using the example of the conversion of a copper salt :

${\ displaystyle \ mathrm {Cu ^ {2 +} + \ Zn \ rightarrow Cu \ downarrow + \ Zn ^ {2+}}}$

In powder form, zinc is a self-igniting (pyrophoric) solid. At room temperature it can heat up in the air without any energy input and finally ignite. The readiness to ignite depends very much on the grain size and the degree of distribution. On contact with water, zinc powder forms flammable gases which can ignite spontaneously.

## Isotopes

31 isotopes from Zn 54 to Zn 85 and a further eleven core isomers are known of zinc . Five of them, the isotopes 64 Zn, 66 Zn, 67 Zn, 68 Zn and 70 Zn are stable and natural. There are no radioactive natural isotopes. The most common isotope is 64 Zn with 48.63% of the natural isotope ratio . This is followed by 66 Zn with 27.90%, 68 Zn with 18.75%, 67 Zn with 4.10% and the rarest natural isotope 70 Zn with a share of 0.62%. The most stable artificial isotope is the beta and gamma emitter (K / β + decay) 65 Zn with a half-life of 244 days. This and the core isomer 69m serve as tracers . The only natural isotope that can be detected by NMR spectroscopy is 67 Zn .

## use

Zinc, crystalline fragment and sublimated.
World zinc production

In 2018 over 13.5 million tons of zinc were produced. Of this, 47% was used for the corrosion protection of iron and steel products by galvanizing . The most important areas of application in terms of consumption quantities are its alloys, preferably those with copper, such as brass , or with aluminum, either as AlZn alloy or with significantly higher zinc contents than Alzen, which is used for parts made by sand casting and permanent mold casting . The standardized magnesium alloys also contain up to 5% zinc. The standardized fine zinc cast alloys , which are mainly cast in the die casting process, but also in sand and chill molds, are far more important. Zinc alloys are also processed into rolled material such as zinc sheets.

### Corrosion protection

Zinc has long been used as an anticorrosive (rust preventive) for steel and iron parts by galvanizing them , i. H. covered with a metallic coating of zinc. The zinc protects actively and passively against corrosion, i. This means, on the one hand, it forms a barrier and, on the other hand, it also protects adjacent exposed iron surfaces and layer defects from corrosion by acting like a sacrificial anode .

The galvanizing can be done in different ways. Methods are hot-dip galvanizing , electro- galvanizing, mechanical coatings , spray galvanizing and zinc flake coatings . They differ in the way the zinc layer is applied, the thickness and thus the durability.

Hot-dip galvanized (individually galvanized) facade of the elementary school at the water tower in Karlsruhe

The oldest galvanizing method is discontinuous hot-dip galvanizing (batch galvanizing). Here, pre-treated and prefabricated steel components (e.g. balcony railings) are immersed in a bath with liquid zinc. In the 1930s, continuous hot-dip galvanizing (strip galvanizing) was used for the first time as a process variant, in which steel strips are galvanized as semi-finished products in a continuous process and only then further processed. Batch galvanizing creates zinc layers that are usually between 50 and 150 µm and, depending on the atmospheric conditions, protect against corrosion for decades. Strip-galvanized sheets have a very thin zinc layer between 7 and 25 µm and therefore only achieve significantly shorter protection periods. The duration of protection of hot-dip galvanized steel can be further increased by an additional coating (duplex system).

In the galvanic process, the zinc layer is applied electrolytically . To do this, the workpiece and a piece of pure zinc are dipped in an acidic or basic solution of a zinc salt. Then DC voltage is applied, with the workpiece forming the cathode and the piece of zinc the anode . Zinc is formed on the workpiece through the reduction of zinc ions. At the same time, the pure zinc of the anode is oxidized and the anode dissolves in the process. A dense zinc layer is created, which in practice is 2.5 to 25 µm. and is therefore significantly lower than with discontinuous hot-dip galvanizing. Theoretically, the zinc layer could also be brought to the thickness of a hot-dip galvanized layer in the galvanic process. However, this would no longer be economical due to the duration (approx. 0.5 µm in one minute) and the energy costs.

In spray galvanizing, the zinc is melted and then sprayed onto the workpiece with the aid of compressed air . The thermal load is lower than with hot-dip galvanizing. This can be important for sensitive materials. If the zinc is applied mechanically to the workpiece, it is called plating . One process that is used for galvanizing small parts, such as screws , is sherardizing . The zinc layer is created by the diffusion of zinc into the iron of the workpiece. Another possible way of applying zinc layers is zinc sprays.

Zinc is used as a sacrificial anode to protect larger steel parts. The object to be protected is conductively connected to the zinc. A galvanic cell is created with zinc as the anode and the object as the cathode. Since the base zinc is now preferentially oxidized and slowly dissolves, the steel part remains unchanged. As long as zinc is present, the piece of steel is thus protected from corrosion.

The white and colored pigments based on zinc compounds also have corrosion protection tasks. Zinc compounds are also part of the phosphating agents ( phosphating ), which enable processes such as bonding sheet metal in the first place.

### Zinc in batteries

Zinc-manganese dioxide cell in section

Metallic zinc is one of the most important materials for negative electrodes ( anodes ) in non-rechargeable batteries and is used on an industrial scale. Examples are alkaline-manganese batteries , zinc-carbon batteries , zinc-air batteries , silver-oxide-zinc batteries and mercury-oxide-zinc batteries . Zinc was also used as an anode in many historical galvanic elements . These include the voltaic column , the Daniell element and the Bunsen element . Zinc is also used to a lesser extent for negative electrodes in accumulators (rechargeable batteries).

The reason for the widespread use of zinc in batteries is the combination of physical and electrochemical properties with good environmental compatibility and relatively low costs. Zinc is a good reducing agent with a high theoretical capacity (0.82 Ah / g). Due to the low standard potential of around −0.76 V or −1.25 V in an alkaline medium, relatively high cell voltages can be achieved. In addition, zinc has good electrical conductivity and is sufficiently stable in aqueous electrolyte solutions.

In order to reduce the corrosion of zinc in the battery and to improve the electrochemical properties, amalgamated zinc with a mercury content of up to 9 percent was used in the past . For environmental reasons, this practice has been almost completely stopped, at least in industrialized countries. In 2006, amalgamated zinc powder will only be used in zinc-air and silver oxide-zinc button cells .

The anode in zinc-carbon batteries is shaped like a zinc can. The cups are produced by multi-stage deep - drawing from sheet zinc or by sudden deformation (English impact extrusion ) of round or hexagonal disks made of thick sheet zinc (so-called domes ). To improve formability and to inhibit corrosion , the zinc used for this purpose contains small amounts of cadmium , lead and / or manganese . In alkaline manganese batteries, zinc powder is used as the active material in the anode. It is mostly produced by atomizing molten zinc in an air jet. To inhibit corrosion, small amounts of other metals are added to the zinc, e.g. B. lead, bismuth , indium , aluminum and calcium .

### Zinc sheet in construction

Zinc sheet roofing (Toruń)

Important zinc products are also semi-finished products , mostly in the form of sheets made of alloyed zinc / titanium zinc. Titanium zinc sheet is used as a material in construction . Today titanium zinc is used almost exclusively , which is more corrosion-resistant, less brittle and therefore significantly more mechanically resilient than unalloyed zinc or the zinc sheet that was common until the 1960s and manufactured using the so-called stack rolling process. Rolled, solid titanium zinc sheet is mainly used for roofing, as facade cladding, for roof drainage ( rain gutters , downpipes), for covers e.g. B. of cornices or exterior window sills or for connections and roof valleys . It lasts up to 100 years and does not need to be serviced or repaired during this time if it has been processed properly. The processing is done by the plumbing trade .

Zinc sheet should not be confused with hot-dip galvanized sheet steel, which is often incorrectly called zinc sheet or tinplate.

Alloy zinc sheet is supplied in coils or in sheets. Metal sheets ( shares ) that are between 40 and 60 centimeters wide and up to 16 meters long are often used for roofing . The material thickness is different, mostly it is 0.7 millimeters. In the case of small-scale elements, the individual sheet metal parts are usually connected by soldering, and in the case of roof coverings, mostly by double folding (double standing seam covering). Due to the thermal expansion of alloyed zinc of 22 · 10 −6 / K, the connections and connections of the zinc profiles must allow material movements.

Modern architects implement extravagant ideas with titanium zinc. Daniel Libeskind has z. B. the Jewish Museum Berlin or the Libeskind Villa in Datteln with a facade made of zinc. Zaha Haddid chose the material for the Transport Museum in Glasgow, which impressively shows the deformation properties of the material.

### Zinc die cast

Diecast zinc car with sprue and not deburred

Zinc die-casting is the common name for parts made from fine zinc cast alloys using the die -casting process. These alloys produce far better values ​​for the cast parts than is possible when casting pure zinc. The alloys are standardized. The alloy GD ZnAl4Cu1 (Z 410) is widely used. Zinc die casting enables - like any die casting process - the production of large quantities. The cast parts are characterized by high dimensional accuracy, have very good mechanical properties and are well suited for surface treatment such as nickel or chrome plating . The range of applications includes automotive accessories and those in machine and apparatus construction, as well as all kinds of fittings , parts for the sanitary industry, for fine appliances and electrical engineering, for metal toys and many household items.

### Coinage

Since zinc as a coin metal costs comparatively little, it was used in times of need, most recently in the two world wars, in the form of zinc alloys for minting coins, but this use as so-called "war metal" was shared with coins made of an aluminum alloy. Since 1982 the core of the US cent (penny) has also been made of zinc.

### Analytics

Reagent grade zinc powder serving as primary standard by pharmacopoeia for setting EDTA - standard solutions .

### Organic chemistry

Zinc serves various purposes in organic synthesis. It functions as a reducing agent and as such can be activated in different ways. One example is the Clemmensen reduction of carbonyl compounds with amalgamated zinc. In addition, allyl alcohols can be reduced to alkenes and acyloins to ketones . The reduction of the aromatic nitro group can lead to different products depending on the reaction conditions: arylamine, arylhydroxylamine, azoarene, N, N'-diarylhydrazine.

In the organometallic area, zinc organyls offer selectivity advantages over Grignard compounds , since they are generally less reactive and tolerate more functional groups - a fact which the Reformatzki reaction makes use of. The organyls can be made directly or by transmetalation . In the presence of asymmetrically complexing auxiliaries , of which catalytic amounts are sometimes sufficient, a stereoselective addition is possible. The effect of amplifying chirality was observed.

Last but not least, halogen elimination and dehalogenation are possible. The Simmons-Smith reaction is one of the rarer preparation methods. The journal Organic Syntheses lists a number of syntheses in which elemental zinc serves as a reagent.

### Production of hydrogen

Zinc is used in the so-called Solzinc process to produce hydrogen . In a first step, zinc oxide is thermally split into zinc and oxygen by solar energy , and in a second step the zinc obtained in this way is converted with water to form zinc oxide and hydrogen.

## Biological importance

Zinc is a trace element for humans and other animals, for plants and for microorganisms .

### Effect in the body

Zinc is one of the indispensable ( essential ) trace elements for the metabolism . It is part of a large number of enzymes , for example RNA polymerase and carbonic anhydrase . Zinc fulfills many different functions in the body. It plays a key role in the sugar , fat and protein metabolism and is involved in the development of genetic material and cell growth . Both the immune system and many hormones need zinc for their function. Zinc promotes the immune system and a. through a weakening of the immune reaction when the immune system reacts excessively. Zinc is also part of zinc finger proteins , which are important transcription factors . In the blood, zinc is mainly bound to albumin .

### Recommended daily dose

According to the World Health Organization, the recommended daily amount for zinc in 1996 was 15 mg for adult men, 12 mg for women, 10 mg for prepubertal children and 5 mg for infants. Because the body can absorb less zinc than expected - only 30 percent can be absorbed - the German Nutrition Society has reduced the recommended amount of zinc for adult men to 10 mg per day and for adult women to 7 mg per day. In the United States, dietary intake is currently 9 mg / day for women and 14 mg / day for men. A sustained increase in zinc intake can lead to a copper deficiency and blood formation disorders.

The recommended tolerable upper intake level of the European Food Safety Authority is 25 mg zinc per day, the Standing Committee on the Scientific Evaluation of Dietary Reference Intakes of the Food and Nutrition Board, Institute of Medicine, National Academy of Sciences , recommends 40 for adults mg / day as the Tolerable Upper Intake Level. According to the magazine Ökotest , the Federal Institute for Risk Assessment recommends a daily intake of a maximum of 2.25 mg zinc via food supplements . In addition, it also regards 25 mg / day as a tolerable upper intake level.

An intake of more than 100 mg per day is not recommended; symptoms such as nausea , vomiting or diarrhea can occur from 200 mg . In humans, the intake of zinc from around 2 g leads to acute symptoms of intoxication. Zinc supplements should only be taken if there is a zinc deficiency (see below) and an increased zinc requirement (e.g. after operations , trauma or burns ).

If zinc is consumed in high doses, e.g. For example, if zinc vapors are inhaled when flame cutting galvanized steels, this creates what is known as “ zinc fever ”. The poisoned person develops flu-like symptoms, sometimes with severe attacks of fever. The symptoms generally subside after 1–2 days.

### performance increase

A study presented at a conference of the United States Nutritional Society in San Diego in 2005 indicated that children who received twice the recommended daily dose of zinc (20 mg) per day experienced marked improvements in mental performance. Zinc improved visual memory , word-finding test performance, and concentration .

### Deficiency symptoms

The trace element cannot be stored in the body; it has to be regularly supplied from the outside. Due to wrong eating habits , zinc deficiency is not uncommon in western countries, especially in infants, the elderly, adolescents and women of childbearing age. It is estimated that two billion people worldwide are deficient in zinc and that this deficiency is partly responsible for the death of a million children each year.

Zinc deficiency leads to underactive gonads , growth disorders and anemia . A low zinc level often manifests itself in a reduced immune function, hair loss , dry skin and brittle nails. Zinc-reactive dermatoses occur in domestic dogs . Zinc deficiency can lead to sterility in men. Zinc deficiency is often caused by a high copper level (e.g. when drinking plenty of drinking water from domestic copper pipe networks), since zinc and copper are antagonists . The same applies to iron , e.g. B. through a very iron-rich diet or the use of iron-containing drugs. The absorption of zinc (as well as other metal ions) from the intestines is also reduced by foods containing phytic acid .

### Zinc in plants

The species Calluna , Erica and Vaccinium can grow on zinc-rich soils because the uptake of excess zinc ions by mycorrhiza is reduced. Zinc deficiencies in soils are among the most common trace element deficiencies in agricultural plants and occur more frequently in soils with a high pH value . Agricultural zinc-deficient soils occur half in Turkey and India, one third in China, and in large parts of Western Australia. Zinc-deficient plants are more susceptible to plant diseases. Zinc occurs in soils primarily as a weather product from stones, but also man-made, such as through the production of fossil energy , mining waste, phosphate fertilizers , pesticides such as zinc phosphide , limestone, slurry, sediments from the sewer system, and corrosion of galvanized metals. Excess zinc is toxic to plants, although this is less common.

### Zinc content in food

Foods high in zinc

The following foods are good sources of zinc:

Peanuts contain a relatively large amount of zinc (approx. 3 mg per 100 g), but like other legumes they also contain a lot of phytic acid , which hinders absorption. The same applies to oilseeds and whole grain products .

Table for food with

a lot of zinc per 100 g a lot of zinc per 100 g zinc on average per 100 g little zinc per 100 g
Oysters 7.0-160.0 mg Brazil nuts 4.0 mg millet 3.4 mg chicken 1.0 mg
Liver (veal, pork, beef) up to 6.3 mg (pork) lamb 2.3-6.0 mg crispbread 3.1 mg fish 0.4-1.1 mg
Soy flour 5.7 mg Lentils (dried) 3.7 mg Pasta (uncooked) 3.1 mg vegetables 0.2-1.0 mg
Emmentaler 30% or 45% FiTr. 4.6 mg Soybeans (dried) 0.7-4.2 mg walnut 2.7 mg yogurt 0.3-0.5 mg
oatmeal 4.0-4.5 mg Corn 2.5-3.5 mg Whole grain biscuits 2.7 mg potato 0.4-0.6 mg
Butter cheese , Tilsiter , Gouda , Edam 3.5-4.0 mg Peanuts (roasted) 3.0-3.5 mg Camembert 2.7 mg Whole milk 0.4 mg
beef 3.0-4.4 mg Mixed wheat bread 3.5 mg Beans (white) 2.6 mg fruit 0.1-0.5 mg

### Zinc as a remedy

Zinc-containing ointments are used for wound healing and skin rashes ( eczema ). Examples of pharmaceutically used zinc salts are zinc acetate , zinc acexamate , zinc chloride , zinc gluconate , zinc oxide , zinc stearate , zinc sulfate , zinc undecylenate .

Zinc acts on the metabolism of the intestinal cells in such a way that less copper is absorbed. Zinc salts (e.g. zinc sulfate , zinc acetate ) are therefore suitable as medicinal substances in the treatment of Wilson's disease , a disease in which the copper metabolism in the liver is disturbed and this leads to an increased accumulation of copper in the liver, the eye, the central nervous system and other organs.

An often-cited meta study by the Indian Institute of Medical Education and Research, which was supposed to prove that zinc had a mitigating effect on colds and shortening the duration of the illness, had such serious deficiencies that it was withdrawn by the Cochrane Collaboration . Older studies could not prove a positive effect either.

In 2004, the World Health Organization (WHO) and the United Nations Children's Fund (UNICEF) issued a statement on the treatment of acute diarrhea , recommending combined treatment with zinc and oral rehydration solution (ORS) . A meta-analysis by the Cochrane Collaboration also found a positive effect of zinc in the treatment of diarrhea in children, limited to children over six years of age and from regions with potential zinc deficiency.

## proof

A simple zinc detection is based on heating a sample with a few drops of a dilute solution of a cobalt salt on a magnesia channel in the Bunsen burner. If zinc is present, the so-called Rinman's green can be seen after a short time .

The quantitative determination can be carried out by means of complexometry with an EDTA standard solution. The various methods of polarography can be used to determine traces . The graphite tube AAS is used in the ultra- trace range . Zinc is a relatively volatile element, which is why matrix modifiers such as palladium and magnesium nitrate are important because they increase the possible pyrolysis temperature. Alternatively, inverse voltammetry or ICP-MS are extremely sensitive instrumental methods.

### Oxides

Zinc oxide forms colorless, hexagonal crystals . It is used as a pigment , in paints , rubber , photocopy paper , and chemicals . Other uses can be found in floor coverings , glasses , enamels , fabrics , plastics , lubricants , in the manufacture of rayon and in pharmaceuticals .

### Halides

Zinc chloride is white and very hygroscopic . It is used in flux for soldering and welding , for fire protection , as a wood preservative , as an etching agent , for the production of parchment paper , rayon , activated carbon , cold water glues, cement and golf balls , as an electrolyte in dry batteries , as a corrosion inhibitor in water treatment , as an agent in the vulcanization of Rubber and used for many other purposes.

Zinc fluoride has a rutile - crystal structure in the space group P 4 2 / mnm (space group # 136.) . It is used for the fluorination of organic compounds , for the preparation of phosphors , for the preservation of wood , for galvanic baths, for galvanizing of steel , for the production of ceramics , in medicaments and in glazes and enamels for porcelain used.

### Other inorganic compounds

Zinc sulfide in the form of sphalerite (zinc blende)
Zinc sulfide in the form of wurtzite

Zinc sulfide occurs naturally as sphalerite (zinc blende) and as wurtzite . It is used as pigment for paints , oil cloth , linoleum , leather and tooth rubber, white, and opaque glass , plastics , fungicides , as semiconductors , photoconductor for solar cells as fluorescent in television and X-ray screens and in light dials of clocks used.

Zinc sulfate is used as a reagent in analytical chemistry , for bleaching of paper , in the production of rayon , as a fire retardant , in fertilizers and as a dietary supplement used.

Zinc carbonate is used as a refractory filler for rubber and plastic compositions , as a feed additive , as a pigment , in cosmetics and in the production of zinc salts, porcelain , ceramics and rubber.

Zinc cyanide is poisonous and harmful to the environment. It is used for plating , for the preparation of insecticides , for electroplating , for the removal of ammonia from the produced gas, to gold recovery , as a chemical reagent , in the medicine and in the chemical analysis used.

### Organic compounds

Zinc acetate is a colorless solid and is used in wood preservation , as a mordant for dyeing , as a food additive , as a feed additive , as a component of adhesives , as a glaze for porcelain and as a reagent for testing for albumin , tannin and phosphate .

Zinc stearate is the zinc salt of stearic acid and belongs to the group of metal soaps . It consists of a zinc ion and two long-chain stearate ions.

## literature

Commons : Zinc  - Collection of pictures, videos and audio files
Wiktionary: Zinc  - explanations of meanings, word origins, synonyms, translations

## Individual evidence

1. a b Harry H. Binder: Lexicon of the chemical elements . S. Hirzel Verlag, Stuttgart 1999, ISBN 3-7776-0736-3
2. The values ​​for the properties (info box) are taken from www.webelements.com (zinc) , unless otherwise stated
3. ^ IUPAC, Standard Atomic Weights Revised 2013
4. entry on zinc in Kramida, A., Ralchenko, Yu., Reader, J. and NIST ASD Team (2019): NIST Atomic Spectra Database (ver. 5.7.1) . Ed .: NIST , Gaithersburg, MD. doi : 10.18434 / T4W30F ( https://physics.nist.gov/asd ). Retrieved June 11, 2020.
5. entry on zinc at WebElements, https://www.webelements.com , accessed on June 11, 2020.
6. ^ A b c N. N. Greenwood, A. Earnshaw: Chemistry of the elements . 1st edition. VCH, Weinheim 1988, ISBN 3-527-26169-9 , p. 1545
7. David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Magnetic Susceptibility of the Elements and Inorganic Compounds, pp. 4-147. The values ​​there are based on g / mol and are given in cgs units. The value specified here is the SI value calculated from it, without a unit of measure
8. a b Yiming Zhang, Julian RG Evans, Shoufeng Yang: Corrected Values ​​for Boiling Points and Enthalpies of Vaporization of Elements in Handbooks . In: Journal of Chemical & Engineering Data . 56, 2011, pp. 328-337, doi: 10.1021 / je1011086
9. ^ GG Graf: Zinc . In: Ullmann's Encyclopedia of Industrial Chemistry . Wiley-VCH Verlag, Weinheim 2005, doi: 10.1002 / 14356007.a28 509
10. a b c Entry on zinc, powder or dust, not stabilized in the GESTIS substance database of the IFA , accessed on August 9, 2016 (JavaScript required)
11. Entry on Zinc in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA), accessed on August 1, 2016. Manufacturers or distributors can expand the harmonized classification and labeling .
12. ^ Initiative Zinc: The Significance of Zinc in History
13. Early brass production in India . In: NZZ online . September 7, 2005
14. Mineral Atlas: Zinc (Wiki)
15. MinDat - Localities for Zinc (English)
16. Stefan Weiß: The large Lapis mineral directory . 4th edition. Christian Weise Verlag, Munich 2002, ISBN 3-921656-17-6 .
17. Galmei ( memento of March 13, 2016 in the Internet Archive ) Entry on the website of the Museum Zinkhütter Hof (visited on April 30, 2016)
18. Webmineral - Mineral Species containing Zinc (Zn)
19. USGS 2016 Minerals Yearbook. (PDF; 276 kB) Accessed November 21, 2017 .
20. USGS: World Mine Production, Reserves, and Reserve Base (PDF; 90 kB)
21. Zinc production. Initiative Zink, accessed on November 21, 2013 .
22. ^ A b A. F. Holleman , E. Wiberg , N. Wiberg : Textbook of Inorganic Chemistry . 102nd edition. Walter de Gruyter, Berlin 2007, ISBN 978-3-11-017770-1 .
23. Entry on zinc. In: Römpp Online . Georg Thieme Verlag, accessed on June 18, 2014.
24. a b G. Audi, FG Kondev, Meng Wang, WJ Huang, S. Naimi: The NUBASE2016 evaluation of nuclear properties . In: Chinese Physics C . 41, 2017, p. 030001, doi : 10.1088 / 1674-1137 / 41/3/030001 ( full text )
25. a b International Lead and Zinc Study Group.
26. a b Information from the Institute for Hot-Dip Galvanizing.
27. Guide to corrosion protection
28. ^ A b F. Sempf: Script “Organozinc Compounds”. ( Memento from June 11, 2007 in the Internet Archive ) (PDF; 174 kB)
29. I. Elphimoff-Felkin, P. Sarda: Reductive Cleavage of allylic Alcohols, ether, or acetate to olefins: 3-methyl Cyclohexene In: Organic Synthesis . 56, 1977, p. 101, doi : 10.15227 / orgsyn.056.0101 ; Coll. Vol. 6, 1988, p. 769 ( PDF ).
30. Reinhard Brückner: reaction mechanisms . 3. Edition. Spektrum Akademischer Verlag, Munich 2004, ISBN 3-8274-1579-9 , p. 776
31. Oliver Kamm: β-Phenylhydroxylamine In: Organic Syntheses . 4, 1925, p. 57, doi : 10.15227 / orgsyn.004.0057 ; Coll. Vol. 1, 1941, p. 445 ( PDF ).
32. ^ HE Bigelow, DB Robinson: Azobenzene In: Organic Syntheses . 22, 1942, p. 28, doi : 10.15227 / orgsyn.022.0028 ; Coll. Vol. 3, 1955, p. 103 ( PDF ).
33. ^ Reformatzky reaction: sketch. Organic Chemistry Portal
34. JC Sauer: 1,1-Dichloro-2,2-Difluoroethylene In: Organic Syntheses . 36, 1956, p. 19, doi : 10.15227 / orgsyn.036.0019 ; Coll. Vol. 4, 1963, p. 268 ( PDF ).
35. Louis F. Fieser: Cholesterol, Δ 5 -Cholesten-3-One, and Δ 4 -Cholesten-3-One In: Organic Syntheses . 35, 1955, p. 43, doi : 10.15227 / orgsyn.035.0043 ; Coll. Vol. 4, 1963, p. 195 ( PDF ).
36. S. Gronowitz, T. Raznikiewicz: 3-Bromothiophene In: Organic Syntheses . 44, 1964, p. 9, doi : 10.15227 / orgsyn.044.0009 ; Coll. Vol. 5, 1973, p. 149 ( PDF ).
37. ^ Simmons-Smith reaction. Organic Chemistry Portal
38. Organic Syntheses: Complete overview of zinc. ( Memento from October 10, 2012 in the web archive archive.today )
39. Wolfgang Maret: Chapter 12. Zinc and Human Disease . In: Astrid Sigel, Helmut Sigel, Roland KO Sigel (eds.): Interrelations between Essential Metal Ions and Human Diseases  (= Metal Ions in Life Sciences), Volume 13. Springer, 2013, ISBN 978-94-007-7499-5 , Pp. 389-414, doi : 10.1007 / 978-94-007-7500-8_12 . PMID 24470098
40. ^ Prasad AS: Zinc in Human Health: Effect of Zinc on Immune Cells . In: Mol. Med. . 14, No. 5-6, 2008, pp. 353-7. doi : 10.2119 / 2008-00033.Prasad . PMID 18385818 . PMC 2277319 (free full text).
41. a b c M. R. Broadley, PJ White, JP Hammond, I. Zelko, A. Lux: Zinc in plants . In: New Phytologist . 173, No. 4, 2007, pp. 677-702. doi : 10.1111 / j.1469-8137.2007.01996.x . PMID 17286818 .
42. Zinc's role in microorganisms is particularly reviewed in: Sugarman B: Zinc and infection . In: Reviews of Infectious Diseases . 5, No. 1, 1983, pp. 137-47. doi : 10.1093 / clinids / 5.1.137 . PMID 6338570 .
43. rhw-Redaktion (Ed.): Ökotrophologie . Volume 2, Verlag Neuer Merkur, 2005, ISBN 3-937346-03-1 , p. 202
44. ^ Ming-Jie Liu et al .: ZIP8 Regulates Host Defense through Zinc-Mediated Inhibition of NF-kB . In: Cell Reports . February 21, 2013, Retrieved November 2, 2013 (PDF, 2.6 MB)
45. ^ A b Hans Konrad Biesalski , Stephan Bischoff, Christoph Puchstein: Nutritional medicine . 4th, completely revised and expanded edition. Georg Thieme, Stuttgart 2010, ISBN 978-3-13-100294-5 .
46. ^ German Society for Nutrition. Retrieved November 25, 2015
47. Independent health advice e. V. Accessed November 25, 2015
48. a b Colin Tidy: Zinc Supplements . Patient.co.uk. March 22, 2010. Retrieved November 2, 2013
49. a b c preparations with zinc plus vitamin C . ( Memento from November 4, 2013 in the Internet Archive ) Ökotest. In: Ratgeber Eating, Drinking and Enjoying . Edition 8/2008, accessed on November 2, 2013
50. Panel on Micronutrients, Subcommittees on Upper Reference Levels of Nutrients and of Interpretation and Use of Dietary Reference Intakes, and the Standing Committee on the Scientific Evaluation of Dietary Reference Intakes: Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium , Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc . 2001
51. European Food Safety Authority: Scientific Opinion: Chromium picolinate, zinc picolinate and zinc picolinate dihydrate added to food supplements for nutritional purposes . 2009, ( full text as PDF file ( Memento from August 10, 2013 in the Internet Archive ))
52. Federal Institute for Risk Assessment (2004): Use of Minerals in Food, p. 24. Accessed on November 25, 2018 .
53. EUFIC : Zinc - a super nutrient? ( Memento from November 24, 2010 in the Internet Archive ) In: Food today . 05/2008
54. rhw-Redaktion (Ed.): Ökotrophologie . Volume 2, Verlag Neuer Merkur, 2005, ISBN 3-937346-03-1 , p. 204
55. Burgerstein zinc tablets 15 mg . In: Swiss Medicines Compendium . September 7, 2009, Retrieved November 2, 2013
56. Zinc makes young people mentally fit . In: Wissenschaft.de. April 5, 2005, accessed September 10, 2019 .
57. Irmgard Niestroj: Practice of orthomolecular medicine: Physiological foundations. Micronutrient therapy . 2nd edition. Georg Thieme Verlag, 2000, ISBN 3-7773-1470-6 ( p. 419 in the Google book search)
58. ^ Ivonne Silvester: Psyche-Physe-Fit . BoD - Books on Demand, ISBN 978-3-8311-2209-7 , pp. 199-200
59. AH Colagar, ET Marzony, MJ Chaichi: Zinc levels in seminal plasma are associated with sperm quality in fertile and infertile men . In: Nutr Res . 29 (2), Feb 2009, pp. 82-88
60. Rainer Elschenbroich: Zinc deficiency due to copper water pipes? (PDF; 87 kB), 2009
61. Zinc - effect and application . ( Memento from May 29, 2012 in the web archive archive.today ) at aktivapo.de
62. a b Austrian Chamber of Pharmacists: Zinc: an important trace element
63. Geoffrey Michael Gadd: Metals, minerals and microbes: geomicrobiology and bioremediation. Archived from the original on October 25, 2014. In: Microbiology . 156, No. 3, March 2010, pp. 609-643. doi : 10.1099 / mic.0.037143-0 . PMID 20019082 .
64. ^ Brian J. Alloway: Zinc in Soils and Crop Nutrition, International Fertilizer Industry Association, and International Zinc Association . 2008. Archived from the original on February 19, 2013.
65. Table - nutritional value and zinc content. Retrieved May 18, 2010 .
66. Recommendation of the German Nutrition Society (DGE). Retrieved May 18, 2010 .
67. Zinc: Help for the skin . on: Medizinauskunft.de , May 16, 2006, accessed on May 27, 2013
68. Meenu Singh, Rashmi R Das: Zinc for the common cold . In: Cochrane Database of Systematic Reviews . doi : 10.1002 / 14651858.CD001364.pub5
69. ^ TJ Caruso, CG Prober, JM Gwaltney: Treatment of naturally acquired common colds with zinc: a structured review . In: Clin. Infect. Dis . 45, No. 5, September 2007, pp. 569-574. doi: 10.1086 / 520031 . PMID 17682990
70. ^ I. Marshall: Zinc for the common cold . In: Cochrane Database Syst Rev . No. 2, 2000, p. CD001364. doi: 10.1002 / 14651858.CD001364 . PMID 10796643
71. WHO / UNICEF JOINT STATEMENT: CLINICAL MANAGEMENT OF ACUTE DIARRHOEA. Archived from the original on July 27, 2007 ; accessed on January 24, 2017 .
72. Marzia Lazzerini, Humphrey Wanzira: Oral zinc for Treating diarrhea in children . In: Cochrane Database of Systematic Reviews . No. 12 , 20 December 2016, doi : 10.1002 / 14651858.CD005436.pub5View (Art. No .: CD005436).
73. a b c d National Pollutant Inventory: Zinc and compounds
74. Norman N. Greenwood, A. Earnshaw: Chemistry of the Elements . 2nd edition, Butterworth-Heinemann, Oxford 1997, ISBN 0-7506-3365-4