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| {{chembox
| | It really is not straightforward to figure out how to repair your car. Nevertheless, you can start off on the proper track by taking the guidance to offered to you in this write-up. You just could be shocked.<br><br> |
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| | verifiedrevid = 445299286
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| | ImageFile = Manganese(IV) oxide.jpg
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| | ImageName = Manganese(IV) oxideMn4O2
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| | ImageFile1 = Rutile-unit-cell-3D-balls.png
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| | ImageName1 =
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| | IUPACName = Manganese oxide<br />Manganese(IV) oxide
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| | OtherNames = [[Pyrolusite]]
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| | Section1 = {{Chembox Identifiers
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| | CASNo = 1313-13-9
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| | PubChem = 14801
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| | CASNo_Ref = {{cascite|correct|CAS}}
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| | ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
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| | ChemSpiderID = 14117
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| | StdInChI_Ref = {{stdinchicite|correct|chemspider}}
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| | StdInChI = 1S/Mn.2O
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| | StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
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| | StdInChIKey = NUJOXMJBOLGQSY-UHFFFAOYSA-N
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| | SMILES = O=[Mn]=O
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| | EINECS = 215-202-6
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| | RTECS = OP0350000
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| }}
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| | Section2 = {{Chembox Properties
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| | Formula = MnO<sub>2</sub>
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| | MolarMass = 86.9368 g/mol
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| | Appearance = Brown-black solid
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| | Density = 5.026 g/cm<sup>3</sup>
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| | Solubility = insoluble
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| | MeltingPt = 535 °C (decomposes)
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| }}
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| | Section4 = {{Chembox Thermochemistry
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| | DeltaHf = −520 kJ·mol<sup>−1</sup><ref name=b1>{{cite book| author = Zumdahl, Steven S.|title =Chemical Principles 6th Ed.| publisher = Houghton Mifflin Company| year = 2009| isbn = 0-618-94690-X|page=A22}}</ref>
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| | Entropy = 53 J·mol<sup>−1</sup>·K<sup>−1</sup><ref name=b1/>
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| }}
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| | Section7 = {{Chembox Hazards
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| | ExternalMSDS = [http://www.inchem.org/documents/icsc/icsc/eics0175.htm ICSC 0175]
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| | EUIndex = 025-001-00-3
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| | EUClass = Harmful ('''Xn''')<br />Oxidizer ('''O''')
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| | RPhrases = {{R20/22}}
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| | SPhrases = {{S2}}, {{S25}}
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| | NFPA-H = 1
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| | NFPA-F = 1
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| | NFPA-R = 2
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| | NFPA-O = OX
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| | FlashPtC = 535
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| }}
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| | Section8 = {{Chembox Related
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| | OtherAnions = [[Manganese disulfide]]
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| | OtherCations = [[Technetium dioxide]]<br/>[[Rhenium dioxide]]
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| | OtherFunctn = [[Manganese(II) oxide]]<br/>[[Manganese(II,III) oxide]]<br/>[[Manganese(III) oxide]]<br/>[[Manganese heptoxide]]
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| | Function = [[manganese]] [[oxide]]s
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| }}
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| }}
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| '''Manganese(IV) oxide''' is the [[inorganic compound]] with the [[chemical formula|formula]] {{chem|MnO|2}}. This blackish or brown solid occurs naturally as the mineral [[pyrolusite]], which is the main ore of [[manganese]] and a component of [[manganese nodule]]s. The principal use for MnO<sub>2</sub> is for dry-cell [[battery (electricity)|batteries]], such as the [[alkaline battery]] and the [[zinc-carbon battery]].<ref name="G&E">{{Greenwood&Earnshaw1st|pages=1218–20}}.</ref> {{chem|MnO|2}} is also used as a [[pigment]] and as a precursor to other manganese compounds, such as {{chem|link=potassium permanganate|KMnO|4|}}. It is used as a [[reagent]] in [[organic synthesis]], for example, for the oxidation of [[allylic]] [[alcohol]]s.
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| ==Structure==
| | There are many how-to videos that you can turn to for auto repairs. Every thing from a easy tire adjust to altering your fuel filter can be found in video type. These videos will take you through every step in creating the repair and will save you the time and the cost of taking it to a mechanic.<br><br>The best way to discover a very good auto mechanic is getting referrals. Can you get a recommendation from a buddy or somebody that you perform with? You can locate out about the top quality of service and the expenses. Folks can inform you what type of knowledge they had and regardless of whether the mechanic was truthful or not.<br><br>Preventative maintenance is quite crucial if you own a automobile. Do not hesitate to devote funds on the tools you want to inspect and keep your vehicle or possessing a mechanic look at your auto regularly. My friend learned about [http://www.prweb.com/releases/used-transmissions-online/transmissions-sale-prices/prweb11075863.htm this page is not affiliated] by browsing newspapers. Maintaining your auto often could support you save a lot on repairs or towing if your automobile breaks down.<br><br>If you feel pressured by the garage or dealership you visit to get your vehicle maintained or repaired, do not hesitate to leave. Dependable mechanics will not place any pressure on their clients and will concentrate on offering high quality service. Learn further on our affiliated paper by navigating to [http://www.prweb.com/releases/toyota-pickup-truck/engines-import-v6-i4/prweb11580889.htm toyota tundra engines]. Follow your gut feeling and keep away from the mechanics who do not look trustworthy.<br><br>Take the time to place these suggestions to use as you face your subsequent auto repair. Do not [http://Browse.deviantart.com/?qh=§ion=&global=1&q=permit+oneself permit oneself] to become overwhelmed or bankrupt due to your ignorance. My cousin learned about [http://www.prweb.com/releases/44re-jeep-grand-cherokee/transmission-for-sale/prweb10997246.htm analyze 1996 jeep grand cherokee transmission] by browsing books in the library. Take control of your scenario with the suggestions you have learned so that you can get the appropriate deal..<br><br>If you adored this information and you would certainly like to get additional details relating to [http://www.kiwibox.com/berserkfer774/blog independent health insurance] kindly go to our own site. |
| Several [[Polymorphism (materials science)|polymorph]]s of {{chem|MnO|2}} are claimed, as well as a hydrated form. Like many other dioxides, {{chem|MnO|2}} crystallizes in the [[rutile]] [[crystal structure]] (this polymorph is called β-{{chem|MnO|2}}), with three-coordinate oxide and octahedral metal centres.<ref name=G&E/> {{chem|MnO|2}} is characteristically [[nonstoichiometric compound|nonstoichiometric]], being deficient in oxygen. The complicated [[solid-state chemistry]] of this material is relevant to the lore of "freshly prepared" {{chem|MnO|2}} in [[organic synthesis]].
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| ==Production==
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| Naturally occurring manganese dioxide contains impurities and a considerable amount of manganese in its [[Manganese#Chemical|3+]] [[oxidation state]]. Only a limited number of deposits contain the γ modification in purity sufficient for the battery industry. The production of [[Ferrite (magnet)|ferrite]] also requires high purity manganese dioxide. Therefore the production of synthetic manganese dioxide is important. Two groups of methods are used, yielding "chemical manganese dioxide" (CMD) and "electrolytical manganese dioxide" (EMD). The CMD is mostly used for the production of ferrites, whereas EMD is used for the production of batteries.<ref name="ChiuZMnO2">{{citation | last = Preisler | first = Eberhard | title = Moderne Verfahren der Großchemie: Braunstein | journal = Chemie in unserer Zeit | year = 1980 | volume = 14 | pages = 137–48 | doi = 10.1002/ciuz.19800140502}}.</ref>
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| ===Chemical manganese dioxide===
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| One of the two chemical methods starts from natural manganese dioxide and converts it using [[dinitrogen tetroxide]] and water to [[manganese(II) nitrate]] solution. Evaporation of the water, leaves the crystalline nitrate salt. At temperatures of 400 °C, the salt decomposes, releasing N<sub>2</sub>O<sub>4</sub> and leaving a residue of purified manganese dioxide.<ref name="ChiuZMnO2"/> These two steps can be summarized as:
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| :MnO<sub>2</sub> + N<sub>2</sub>O<sub>4</sub> <math>\overrightarrow{\leftarrow}</math> Mn(NO<sub>3</sub>)<sub>2</sub>
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| In the other chemical process, manganese dioxide ore is reduced by heating with oil or coal. The resulting [[manganese(II) oxide]] is dissolved in [[sulfuric acid]], and the filtered solution is treated with [[ammonium carbonate]] to precipitate MnCO<sub>3</sub>. The carbonate is [[calcined]] in air to give a mixture of manganese(II) and manganese(IV) oxides. To complete the process, a suspension of this material in sulfuric acid is treated with [[sodium chlorate]]. [[Chloric acid]], which forms in situ, converts any Mn(III) and Mn(II) oxides to the dioxide, releasing chlorine as a by-product.<ref name="ChiuZMnO2"/>
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| ===Electrolytical manganese dioxide===
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| Electrolytical manganese dioxide (EMD) is used in [[zinc-carbon batteries]] together with [[zinc chloride]] and [[ammonium chloride]]. EMD is commonly used in zinc manganese dioxide rechargeable alkaline (Zn RAM) cells also. For these applications, purity is extremely important.
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| ==Reactions==
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| The important reactions of {{chem|MnO|2}} are associated with its redox, both oxidation and reduction.
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| ===Reduction===
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| {{chem|MnO|2}} is the principal [[Precursor (chemistry)|precursor]] to [[ferromanganese]] and related alloys, which are widely used in the steel industry. The conversions involve [[carbothermal reduction]] using [[Coke (fuel)|coke]]:
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| :{{chem|MnO|2}} + 2 C → Mn + 2 CO
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| The key reactions of {{chem|MnO|2}} in batteries is the one-electron reduction:
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| :{{chem|MnO|2}} + e<sup>−</sup> + H<sup>+</sup> → MnO(OH)
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| {{chem|MnO|2}} [[catalysis|catalyses]] several reactions that form {{chem|O|2}}. In a classical laboratory demonstration, heating a mixture of [[potassium chlorate]] and manganese dioxide produces oxygen gas. Manganese dioxide also catalyses the decomposition of [[hydrogen peroxide]] to oxygen and [[water (molecule)|water]]:
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| :2 H<sub>2</sub>O<sub>2</sub> → 2 H<sub>2</sub>O + O<sub>2</sub>
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| Manganese dioxide decomposes above about 530 °C to [[manganese(III) oxide]] and oxygen. At temperatures close to 1000 °C, the [[mixed-valence compound]] Mn<sub>3</sub>O<sub>4</sub> forms. Higher temperatures give MnO.
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| Hot concentrated [[sulfuric acid]] reduces the MnO<sub>2</sub> to [[manganese(II) sulfate]]:<ref name="G&E"/>
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| :2 MnO<sub>2</sub> + 2 H<sub>2</sub>SO<sub>4</sub> → 2 MnSO<sub>4</sub> + O<sub>2</sub> + 2 H<sub>2</sub>O
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| The reaction of [[hydrogen chloride]] with MnO<sub>2</sub> was used by [[Carl Wilhelm Scheele]] in the original isolation of [[chlorine]] gas in 1774:
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| :MnO<sub>2</sub> + 4 HCl → MnCl<sub>2</sub> + Cl<sub>2</sub> + 2 H<sub>2</sub>O
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| As a source of hydrogen chloride, Scheele treated [[sodium chloride]] with concentrated sulfuric acid.<ref name=G&E>{{Greenwood&Earnshaw1st}}.</ref>
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| ::''E''<sup><s>o</s></sup> (MnO<sub>2</sub>(s) + 4 H<sup>+</sup> + 2 e<sup>−</sup> {{eqm}} Mn<sup>2+</sup> + 2 H<sub>2</sub>O) = +1.23 V
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| ::''E''<sup><s>o</s></sup> (Cl<sub>2</sub>(g) + 2 e<sup>−</sup> {{eqm}} 2 Cl<sup>−</sup>) = +1.36 V
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| The [[standard electrode potential]]s for the [[half reaction]]s indicate that the reaction is [[endothermic]] at pH = 0 (1 M [H<sup>+</sup>]), but it is favoured by the lower [[pH]] as well as the evolution (and removal) of gaseous chlorine.
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| This reaction is also a convenient way to remove the manganese dioxide [[precipitate]] from the [[ground glass joint]]s after running a reaction (i. e., an oxidation with [[potassium permanganate]]).
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| ===Oxidation===
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| Heating a mixture of [[potassium hydroxide|KOH]] and {{chem|MnO|2}} in air gives green [[potassium manganate]]:
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| :2 MnO<sub>2</sub> + 4 KOH + O<sub>2</sub> → 2 K<sub>2</sub>MnO<sub>4</sub> + 2 H<sub>2</sub>O
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| Potassium manganate is the precursor to [[potassium permanganate]], a common oxidant.
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| ==Applications==
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| The predominant application of MnO<sub>2</sub> is as a component of [[dry cell]] batteries, so called [[Leclanché cell]], or [[Zinc–carbon battery|zinc–carbon batteries]]. Approximately 500,000 [[tonne]]s are consumed for this application annually.<ref name=Ullmann>{{citation | first = Arno H. | last = Reidies | contribution = Manganese Compounds | title = Ullmann's Encyclopedia of Industrial Chemistry | publisher = Wiley-VCH | location = Weinheim | year = 2002 | doi = 10.1002/14356007.a16_123 | volume = 20 | pages = 495–542 | isbn = 3-527-30385-5}}.</ref> Other industrial applications include the use of {{chem|MnO|2}} as an inorganic [[pigment]] in [[ceramic]]s and in [[glassmaking]].
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| ===Organic synthesis===<!--used in ind production of p-quinone from aniline-->
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| A specialized use of manganese dioxide is as oxidant in [[organic synthesis]].<ref>{{citation | last1 = Cahiez | first1 = G. | last2 = Alami | first2 = M. | last3 = Taylor | first3 = R. J. K. | last4 = Reid | first4 = M. | last5 = Foot | first5 = J. S. | contribution = Manganese Dioxide | title = Encyclopedia of Reagents for Organic Synthesis | editor-first = Leo A. | editor-last = Paquette | year = 2004 | publisher = J. Wiley & Sons | location = New York}}.</ref> The effectiveness of the reagent depends on the method of preparation, a problem that is typical for other heterogeneous reagents where surface area, among other variables, is a significant factor.<ref>{{citation | last1 = Attenburrow | first1 = J. | last2 = Cameron | first2 = A. F. B. | last3 = Chapman | first3 = J. H. | last4 = Evans | first4 = R. M. | last5 = Hems | first5 = B. A. | last6 = Jansen | first6 = A. B. A. | last7 = Walker | first7 = T. | journal = J. Chem. Soc. | year = 1952 | page = 1094}}.</ref> The mineral [[pyrolusite]] makes a poor reagent. Usually, however, the reagent is generated in situ by treatment of an aqueous solution KMnO<sub>4</sub> with a Mn(II) salt, typically the sulfate. MnO<sub>2</sub> oxidizes [[allylic]] alcohols to the corresponding [[aldehyde]]s or [[ketone]]s:<ref>{{OrgSynth | author = Leo A. Paquette and Todd M. Heidelbaugh | title = (4S)-(−)-tert-Butyldimethylsiloxy-2-cyclopen-1-one | |collvol = 9 | collvolpages = 136 | year = | prep = cv9p0136}} (this procedure illustrates the use of MnO2 for the oxidation of an allylic alcohol.</ref>
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| ::cis-RCH=CHCH<sub>2</sub>OH + MnO<sub>2</sub> → cis-RCH=CHCHO + “MnO” + H<sub>2</sub>O
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| The configuration of the [[double bond]] is conserved in the reaction. The corresponding [[acetylenic]] alcohols are also suitable substrates, although the resulting [[propargylic]] aldehydes can be quite reactive. [[Benzylic]] and even unactivated alcohols are also good substrates. 1,2-[[Diol]]s are cleaved by MnO<sub>2</sub> to [[dialdehyde]]s or [[diketone]]s. Otherwise, the applications of MnO<sub>2</sub> are numerous, being applicable to many kinds of reactions including [[amine]] oxidation, aromatization, [[oxidative coupling]], and [[thiol]] oxidation.
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| ===Pigment===
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| Manganese dioxide was one of the earliest natural substances used by human ancestors. It was used as a [[pigment]] at least from the [[middle paleolithic]]. It was possibly used first for [[body painting]], and later for [[cave painting]]. Some of the most famous early cave paintings in Europe were executed by means of manganese dioxide.
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| ==Hazards==
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| Manganese dioxide can slightly [[stain]] human skin if it is damp or in a [[heterogeneous mixture]], but the stains can be washed off quite easily with some rubbing.
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| ==References==
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| {{Reflist}}
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| ==External links==
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| * [http://www.mn-consortium.org/ REACH Mn Consortium]
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| * [http://www.orgsyn.org/orgsyn/chemname.asp?nameID=33430 Index of Organic Synthesis procedures utilizing MnO<sub>2</sub>]
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| * [http://www.organic-chemistry.org/chemicals/oxidations/manganese(IV)oxide.shtm Example Reactions with Mn(IV) oxide]
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| * [http://www.npi.gov.au/database/substance-info/profiles/52.html National Pollutant Inventory - Manganese and compounds Fact Sheet]
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| * [http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=14801 PubChem summary of MnO<sub>2</sub>]
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| * [http://www.inchem.org/documents/icsc/icsc/eics0175.htm International Chemical Safety Card 0175]
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| *[http://web.archive.org/web/20041124065033/ceramic-materials.com/cermat/education/139.html Potters Manganese Toxicity by Elke Blodgett]
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| {{Manganese compounds}}
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| {{DEFAULTSORT:Manganese Dioxide}}
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| [[Category:Manganese compounds]]
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| [[Category:Manganese minerals]]
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| [[Category:Oxide minerals]]
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| [[Category:Oxides]]
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| [[Category:Inorganic pigments]]
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It really is not straightforward to figure out how to repair your car. Nevertheless, you can start off on the proper track by taking the guidance to offered to you in this write-up. You just could be shocked.
There are many how-to videos that you can turn to for auto repairs. Every thing from a easy tire adjust to altering your fuel filter can be found in video type. These videos will take you through every step in creating the repair and will save you the time and the cost of taking it to a mechanic.
The best way to discover a very good auto mechanic is getting referrals. Can you get a recommendation from a buddy or somebody that you perform with? You can locate out about the top quality of service and the expenses. Folks can inform you what type of knowledge they had and regardless of whether the mechanic was truthful or not.
Preventative maintenance is quite crucial if you own a automobile. Do not hesitate to devote funds on the tools you want to inspect and keep your vehicle or possessing a mechanic look at your auto regularly. My friend learned about this page is not affiliated by browsing newspapers. Maintaining your auto often could support you save a lot on repairs or towing if your automobile breaks down.
If you feel pressured by the garage or dealership you visit to get your vehicle maintained or repaired, do not hesitate to leave. Dependable mechanics will not place any pressure on their clients and will concentrate on offering high quality service. Learn further on our affiliated paper by navigating to toyota tundra engines. Follow your gut feeling and keep away from the mechanics who do not look trustworthy.
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