Lead

of these articles is concerned with the metal lead. For the carp fish of the same name, see under Brachse.
Characteristics
thallium - lead - bismuth
SN
Pb
Uuq

[Xe] 4f 14 5d 10 6s 2 6p 2
,208
82
Pb

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generally
name, symbol, ordinal number lead, Pb, 82
series of metals
group, period, block 14 (IVA), 6, p
appearance bluish knows
proportion at the Earth's shell 2· 10 -3 %
atomically
atomic mass 207.2
atomic radius (computed) 180 (154) pm
Kovalenter radius 147 pm
van the Waals radius 202 pm
Elektronenkonfiguration [Xe] 4 f 14 5 D 10 6 s 2 6p 2
electrons per energy level 2, 8,18, 32, 18, 4
electron affinity 4.35 eV
1. Ionization energy 715.6 kJ/mol
2. Ionization energy 1450.5 kJ/mol
3. Ionization energy 3081.5 kJ/mol
4. Ionization energy 4083 kJ/mol
5. Ionization energy 6640 kJ/mol
physically
state of aggregation (magnetism) firmly
crystal structure cubically face-centered
density (Mohshärte) 11340 kg/m ³ (1,5)
melting point 600.61 K (327.46 °C)
boiling point 2022 K (1749 °C)
molecular volume 18,26 · 10 -3 m 3 /mol
heat of vaporization 177.7 kJ/mol
heat of fusion 4.799 kJ/mol
steam pressure 4,21 · 10,-07 Pa with 600 K
speed of sound 1260 m/swith 293,15 K
specific thermal capacity 129 j (kg · K)
Electrical conductivity 4,81 · 10 6 S /m
heat conductivity 35.3 w (m · K)
Chemically
oxidation conditions of 2, 4
hydrides and oxides (basicity) (amphoter)
Normalpotenzial -0.1262 V (Pb 2+ + 2e - → Pb)
Elektronegativität of 2.33 (Pauling scale)
isotopes
isotope NH t 1/2 ZM CPU M eV ZP
202 Pb {syn.} 52500 A alpha
Epsilon
2.598
0.050
198 Hg
202 tl
203 Pb {syn.} 51.873 h Epsilon 0,975 203 tl
204 Pb 1.4% >1,4 · 10 17 A alpha 2.186 200 Hg
205 Pb {syn.} 1,53 · 10 7 A Epsilon 0.051 205 tl
206 Pb 24.1% Pb 207 Pb are stable with
124 neutrons 22.1% Pb is stably with 125 neutrons
208 Pb 52.4% Pb is stably with 126 neutrons
209 Pb {syn.} 3.253 h beta 0.644 209 Bi
210 Pb {syn.} 22.3 A alpha
beta
3.792
0.064
206 Hg
210 Bi
As far as possible and common, SI-UNITs are used.
If not differently notes,
the indicated data apply with standard conditions.

Lead (lat. p lum b over, of plumbeus: bleiern,) a chemical element is blunt , lead-heavily. Chemical symbol: Pb. The nameLead is meant as many indogermanischen origin and as resplendent, bright or shining. Lead is a heavy metal with the ordinal number 82. The sturdy lead isotopes Pb 206, Pb 207 and Pb 208, the heaviest sturdy atomic nuclei at all, are the final products of the natural Decay chains of the radioactive elements. The metal can be deformed easily and can also into arbitrary form be poured. In the English word for plumbers („more plumber “) still the word is lead. Finally in former times world-wide all water pipes from lead were manufactured. Also thosePlombe has the word trunk Plumbum.

Table of contents

History

in the early Bronzezeit was used lead beside antimony and arsenic, in order to produce bronze, until tin interspersed itself to a large extent. Already the Babylonier knew vases from lead, the Romans used the metal as material for lead containers, as centrifuge projectile, for Plomben (name) and water pipelines. The high demand for lead and above all tin is stated even as a reason for Roman occupation Britanniens - in the southwest region Cornwall were at that time important ore occurrences. Also in The Romans up to their retreat won Westphalia after the Varusschlacht lead. The Roman lead processing led to one to today provable environmental pollution: Ice cores made of Greenland show 5 between that. Century v. Chr. and that 3. Century n. Chr. onemeasurable rise of the Bleigehalts in the atmosphere.

occurrence

lead ore

lead ore seems to PbS (Bleiglanz) in chemical compounds as lead sulfide. This mineral is also the most important commercial source for the production again lead.

One finds the largest occurrences in China, the USA, Australia, Russia and Canada. In Europe Sweden and Poland are the countries with the largest occurrences.

Also in Germany became in the Jülicher Börde, in the resin (Goslar/Rammelsberg) and in Saxonia (free mountain) in the past lead ore diminished, smelts and improves.

The most important source for lead is today the recycling of old lead products.

the largest promotion nations

the most important promotion nations for lead are Australia andChina, followed of the USA, Peru and Mexico. In Europe at present Poland is to call Ireland and Sweden as the largest lead producers.

The largest promotion nations (2003)
rank country deliveries
(in Tsd. t)
Country struggled deliveries
(in Tsd. t)
1 Australia 677 11 Sweden 50,3
2 China 670 12 Morocco 50
The 3 USA 448,7 13 Kazakhstan 38,2
4 Peru 308,9 14 India 34
5 Mexico 144,3 15 Bulgaria 31,3
6 Canada 77,1 16 North Korea 30
7 Poland 77 17 Greece 28,3
8 Russian Föd. 63 18 Iran 28
9 South Africa 53 19 Romania 14,1
10 Ireland 50,3 20 Namibia 13,4

source: Trade paper - the world in figures (2005)

production and representation

of pieces of lead in a glass ampul

of lead ores become todayin the open mining or promoted in the foundation engineering. Smelting of pure ore occurs today only very rarely. Almost exclusively the promoted ore is enriched to a concentrate. Of this concentrate lead is in two ways made.

  • Roasting reduction work:

This procedureruns in two stages, roasting and the reduction. When roasting the sulfur is removed. The lead sulfide PbS (Bleiglanz) is converted to lead oxide PbO.

<math> \ mathrm {2 PbS + 3 O_2 \ rightarrow 2 PbO + 2 SO_2}< /math>.

The reactionwith sintering plants one accomplishes. Subsequently, the reduction of the PbO to metallic lead takes place in the shaft furnace by coke. This coke burns to CO (Carbon monoxide), which reduces the PbO then.

<math> \ mathrm {PbO + CO \ rightarrow Pb + CO_2}< /math>.
  • Reaction work:

Into thatlast years the so-called reaction work is likewise accomplished. This makes the lead production possible in a step:

<math> \ mathrm {PbS + 2PbO \ rightarrow 3Pb + SO_2}< /math>
  • Refining:

Developing Werkblei (raw lead) often contains 2-5% impurities, among them copper, silver, tin, zinc, arsenic and bismuth. ThoseRefining and Entschlickerung contribute by the Aufreinigen and marked out these byproducts substantially for the economy of the lead production. This is done primarily by salts or air with selective oxidation of a component of the melt or displacing out of the melt via mixed crystal formationand taking the so-called off. Foam. Also galvanic procedures are common for higher purities.

Standardized commercialusual Hüttenblei (Weichblei) with 99,9% to 99.97% purity develops (e.g. Eschweiler Raffiné) or fine lead with 99,985% to 99.99% (DIN 1719, become outdated) according to thatIntended purpose are also designations such as cable lead common. Current standards such as DIN EN 12659 do not know these still common designations any longer.

use

metal

  • in lead-acid batteries as chemical energy stores (see connections)
  • because of its high density asWeight:
    • as counter balances for balancing car wheels (since 1. July 2003 with passenger car new vehicle and since 1. July 2005 with all passenger cars (until 3.5 t) forbade - with it this replaces smoothly by zinc
    • or copper weights) as lead chain in curtains,hang
    • when dipping leads are used, in order to adjust the lift of diver and equipment.
    • the stabilization of ships
    • as shock-mounts in vibration-sensitive (auto) parts
    • for special applications of the noise control
  • because of its shield effect against high-energy radiation and elementary particle it becomes the protection for examplein x-ray units in addition, assigned in cathode ray tubes (computer screens, television sets, etc.).
  • for sharper radiographs than scattered ray rasters.
  • because of its chemical stability approximately and. A. Sulfuric acid and bromine by passivation as corrosion protection in the apparatus and tank construction.
  • Lead became also the production of Pipes uses. Due to the toxicity of the lead and its connections (lead poisoning) lead pipes come however for the 1970er years no longer to the employment. Despite a formed lime layer in the pipes the lead separates further in the drinking water. According to experienceafter few meters the limit value of the valid drinking water regulation is already not kept.
  • Lead was used long time also as main material for window versions, as one can often still recognize it by medieval Kirchenfenstern.
  • in old buildings from natural stone for the connection ofStones by cast in metal clips or metal pegs
  • as roofing or for roof conclusions
  • in earlier times as well as this very day lead than material for projectiles is used, both for centrifuges and for Feuerwaffen to in 21. Century („powders and lead “). InKartät so mentioned chopped lead was fired. The soldiers manufactured their projectiles themselves, and it was not uncommon that soldiers stole all lead, which they could find, in order to make ammunition from it. Nowadays becomes around the lead usually stilla coat from copper poured, in order to work against a Verbleiung of the run and to achieve a better Führigkeit and stability of the ammunition.
  • Customs to Silvester are the lead pouring, with that liquid lead (nowadays also tin) in cold water toSolidify one brings. On the basis the coincidentally developing forms over the future one associates.

alloying constituent

  • hard lead in connection with tin and antimony
  • Letternmetall in connection with tin and antimony to the production of type characters
  • babbitt metal to the production of camps
  • as alloying constituent of tin - plumb bob is used lead in the solder among other things in electro-technology. The use of lead in plumb bobs amounted to 1998 world-wide about 20,000 tons. The EEC guideline 2002/95/EG RoHS banishes lead to a large extent starting from July 2006 from that Soldering technique.

connections

  • as chemical energy stores in lead-acid batteries, with delivery of energy transformation of lead and lead dioxide in lead sulfate.
  • as tetraethyl lead Pb (C 2 H 5) 4 serves fuels as additive, as knock inhibitor in carburetors, todayhowever only with Flugbenzin.
  • as lead oxide PbO is admitted it with the production of the lead crystal of the Glasschmelze.
  • as Farbpigmente white lead
    • Pb (OH) serves 2·2 PbCO 3, the white pigment with the highest cover strength
    • chrome-yellow PbCrO 4 and Chrome-red PbO 2·PbCrO 4
    • red lead “Pb 3 O 4 “Pb 2 [PbO 4] is used, a red pigment, also as rust preventives
  • historically as rather poisonous lead sugar for the sweet one in particular of wine.

biological meaning

toxicity

acute highly toxically are the volatile Organobleiverbindungen, likewise many tri alkyl lead connections. Their handling requires relevant safety precautions.

With unique admission of metallic lead or the usually with difficulty soluble lead salts a poison effect is to be noticed only with high dosage. Howeverenrich themselves even smallest quantities, during a longer period constantly taken, in the body, there them e.g. in the bones to be stored and be only very slowly again separated. Lead can cause so a chronic poisoning, itself among other things inHeadache, tiredness, Abmagerung and defects of the blood formation, the nervous system and the musculature shows. Lead can cause also fruit damage and generation inability, in extreme cases can the lead poisoning to death lead. The use of lead in mess kits is therefore today forbidden, Zinngeschirre must lead free its, likewise many further utensils.

Further details under lead poisoning, also: Gressenicher illness, servant illness and lead children.

lead free

the use of lead, lead alloys and lead connections increasing legal restrictions is subjected to ways of its toxicity. Appropriate productsand applications are completely replaced either (as Bleitetraethylen in the gasoline) or the Bleigehalt by limit values on one the technical pollution corresponding value limits (z. B. Tin and plumb bob). These products are called gladly „lead free “. Limit values there are and.A. in the legislation around the so-called.RoHS (guideline 2002/95/EG), which plans 1000ppm (0.1%). The limit value for packing with 100ppm (guideline 94/62/EG) is stricter.

The political will for replacing the lead applies also, where the use due to thatCharacteristics technically or economically interesting, the health danger would be small and a recycling at meaningful expenditure would be possible (z. B. Lead as roofing).

proof

a possibility of accomplishing a microscopic proof reaction for lead ions is the proof with potassium iodides.

The sample is loosened in diluted hydrochloric acid and evaporated carefully up to the crystallization. The arrears are taken up with a drop water and shifted afterwards with a crystal potassium iodide. Yellow hexagonal lamellas after short time (lead (II) develop - iodid), which show high interference colors between crossed polarizers. To some time it comes to the redissolution of the initially yellow crystals, and the colorless Kaliumtetraiodoplumbat (II) develops.

One points lead ions in solution alternatively also with sulfide solution post it falls black lead sulfidePbS out so e.g. from lead ii-nitrate solution:

<math> \ mathrm {S^ {\ operator name {2}} + Pb (NO_3) _2 \ longrightarrow PbS + 2 NO_3^ {\ operator name {-}}} </math>

The proof is disturbed however by other heavy metal - cations. With iodine ID solution yellow lead II iodid PbI 2 falls out (even when using only inhot water soluble lead ii-chloride):

<math> MgI_2 + PbCl_2 \ rightarrow MgCl_2 + PbI_2 \ downarrow< /math>

With Dichromatlösung (orange, sourly) yellow Bleichromat out the pigment falls chrome-yellow PbCrO 4

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