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| | Possibly the most useful place to find details about claims filed against homeowner insurance companies will be the Better Business Bureau. Just visit the site, decide to check out a small business, and enter the name and location of the homeowner insurance provider you need to study. <br><br>As soon as you get the organization in qu... <br><br>Many individuals want to browse the claims made against a insurance company before deciding whether to complete business with that company. They are able to try this online. <br><br>Probably the most readily useful spot to find information about claims filed against homeowner insurance providers will be the Better Business Bureau. Going To [http://pills-info.info/2014/08/06/acquiring-law-school-info/ learn about orange county seo complaints] likely provides cautions you might use with your girlfriend. Simply visit the site, decide to check out a small business, and enter the location and name of the homeowner insurance company you need to research. <br><br>As soon as you discover the company in question, youll be offered with: <br><br>Standard company information This includes the start time, administrative/management personnel, contact information, other company names, etc. <br><br>Membership status Although the BBB studies problem information about insurance companies no matter membership status, if your [http://www.ehow.com/search.html?s=organization organization] is an associate, it shows they support the public services supplied by the BBB. <br><br>Complaint issues There are always a variety of issues customers may have reported billing/collection, about: contract, revenue training, supply, restoration, service, client service, and refund/exchange. To research more, please check-out: [http://www.hpggsc.com/showthread.php?tid=9913 complaint]. <br><br>Resolution information The BBB provides the amount of claims against the homeowner insurance provider in the last 3 years. The BBB will state whether the problem was successfully resolved, or if the company made an endeavor to solve the matter but was rejected by the consumer. (In such instances since the latter, the BBB will state whether they believe the companys work was acceptable or not.) <br><br>As youre reading each homeowner insurance companys report, remember the size of the organization. Its affordable for large companies with many customers to get more problems than small companies with fewer customers. <br><br>Also, pay more attention to how a complaints were handled compared to the actual number of complaints. If a insurance company has had many complaints and treated all of them in a way, its could possibly be doing much better than a insurance company thats just had a complaints but neglected to take care of them in a satisfactory way..<br><br>When you loved this informative article and you would love to receive more info with regards to health news articles ([http://storify.com/imperfecti113 related web site]) generously visit our web-page. |
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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==
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| 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]]
| |
Possibly the most useful place to find details about claims filed against homeowner insurance companies will be the Better Business Bureau. Just visit the site, decide to check out a small business, and enter the name and location of the homeowner insurance provider you need to study.
As soon as you get the organization in qu...
Many individuals want to browse the claims made against a insurance company before deciding whether to complete business with that company. They are able to try this online.
Probably the most readily useful spot to find information about claims filed against homeowner insurance providers will be the Better Business Bureau. Going To learn about orange county seo complaints likely provides cautions you might use with your girlfriend. Simply visit the site, decide to check out a small business, and enter the location and name of the homeowner insurance company you need to research.
As soon as you discover the company in question, youll be offered with:
Standard company information This includes the start time, administrative/management personnel, contact information, other company names, etc.
Membership status Although the BBB studies problem information about insurance companies no matter membership status, if your organization is an associate, it shows they support the public services supplied by the BBB.
Complaint issues There are always a variety of issues customers may have reported billing/collection, about: contract, revenue training, supply, restoration, service, client service, and refund/exchange. To research more, please check-out: complaint.
Resolution information The BBB provides the amount of claims against the homeowner insurance provider in the last 3 years. The BBB will state whether the problem was successfully resolved, or if the company made an endeavor to solve the matter but was rejected by the consumer. (In such instances since the latter, the BBB will state whether they believe the companys work was acceptable or not.)
As youre reading each homeowner insurance companys report, remember the size of the organization. Its affordable for large companies with many customers to get more problems than small companies with fewer customers.
Also, pay more attention to how a complaints were handled compared to the actual number of complaints. If a insurance company has had many complaints and treated all of them in a way, its could possibly be doing much better than a insurance company thats just had a complaints but neglected to take care of them in a satisfactory way..
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