https://www.sciencemadness.org/smwiki/index.php?title=Purple_acid&feed=atom&action=historyPurple acid - Revision history2024-03-29T09:29:20ZRevision history for this page on the wikiMediaWiki 1.25.1https://www.sciencemadness.org/smwiki/index.php?title=Purple_acid&diff=14902&oldid=prevDiachrynic: /* Chemical */2023-01-28T13:07:21Z<p><span dir="auto"><span class="autocomment">Chemical</span></span></p>
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<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>Dilution with water also destroys the colored compound. If strongly cooled, the solution changes to an intense red, so that if a solution is too weak to possess a marked color at the ordinary temperature, the presence of the "purple acid" can easily be detected by cooling in a mixture of [[acetone]] and [[carbon dioxide|dry ice]].</div></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>Dilution with water also destroys the colored compound. If strongly cooled, the solution changes to an intense red, so that if a solution is too weak to possess a marked color at the ordinary temperature, the presence of the "purple acid" can easily be detected by cooling in a mixture of [[acetone]] and [[carbon dioxide|dry ice]].</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'>−</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div><del class="diffchange diffchange-inline">Certain of </del>the <del class="diffchange diffchange-inline">salts in </del>solution have a stronger color than <del class="diffchange diffchange-inline">the free acid</del>, and in some cases <del class="diffchange diffchange-inline">are more stable</del>. A deep blue solution of the copper salt may be obtained by the reduction of nitrosylsulfuric acid in sulphuric acid by mercury in the presence of [[copper]]. It has been suggested that the color in the "brown ring" test for a nitrate is due to the formation of the ferrous salt of "purple acid," but this is improbable.<ref>https://www.degruyter.com/document/doi/10.1515/znb-1953-1011/html</ref></div></td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins class="diffchange diffchange-inline">Some metal ions cause </ins>the solution <ins class="diffchange diffchange-inline">to </ins>have a stronger color than <ins class="diffchange diffchange-inline">it would have in their absence</ins>, and in some cases <ins class="diffchange diffchange-inline">increase the stability. In the older texts this was interpreted as formation of salts of purple acid</ins>. A deep blue solution of the <ins class="diffchange diffchange-inline">"</ins>copper salt<ins class="diffchange diffchange-inline">" for example </ins>may be obtained by the reduction of nitrosylsulfuric acid in sulphuric acid by mercury in the presence of [[copper]]. It has been suggested that the color in the "brown ring" test for a nitrate is due to the formation of the ferrous salt of "purple acid," but this is improbable.<ref>https://www.degruyter.com/document/doi/10.1515/znb-1953-1011/html</ref></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div> </div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins class="diffchange diffchange-inline">The idea of salt formation is incompatible with the modern notion of purple acid as the cationic species N<sub>2</sub>O<sub>2</sub><sup>+</sup>. The deep blue color of the "copper salt" has instead be interpreted as a complex like CuSO<sub>4</sub> · NO or [CuNO]<sup>2+</sup>.<ref>N. Tsumori, Q. Xu, ''Bulletin of the Chemical Society of Japan'' '''2002''', 75(8), 1861–1862. [https://doi.org/10.1246/bcsj.75.1861 10.1246/bcsj.75.1861]</ref><ref>Gmelins Handbuch der anorganischen Chemie - Kupfer Teil B Lieferung 1, Verlag Chemie GmbH Weinheim Bergstr. 1958, page 579, see [https://www.sciencemadness.org/whisper/viewthread.php?tid=156855&page=2#pid653397 this post].</ref> The optical spectra of these copper(II)-nitrogen monoxide complexes is very different from the spectrum of free purple acid, and the similarity in color seems to be coincidental. Therefore, when copper(II) is added to purple acid, the solution seems to serve purely as a donor of NO.</ins></div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>===Physical===</div></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>===Physical===</div></td></tr>
</table>Diachrynichttps://www.sciencemadness.org/smwiki/index.php?title=Purple_acid&diff=14900&oldid=prevDiachrynic at 11:09, 24 January 20232023-01-24T11:09:56Z<p></p>
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<td colspan='2' style="background-color: white; color:black; text-align: center;">Revision as of 11:09, 24 January 2023</td>
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<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>   }}</div></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>   }}</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>}}</div></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>}}</div></td></tr>
<tr><td class='diff-marker'>−</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>'''Sulfonitronic acid''', '''blue acid''' or more commonly '''purple acid''', is an unstable inorganic compound, which yields a purple solution in [[sulfuric acid]], hence its name.  </div></td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>'''Sulfonitronic acid''', '''blue acid''' or more commonly '''purple acid''', is an unstable inorganic compound, which yields a purple solution in [[sulfuric acid]], hence its name<ins class="diffchange diffchange-inline">. It has not been isolated in the pure state and is only known in solution.<ref>Gmelins Handbuch der anorganischen Chemie - Schwefel Teil B Lieferung 3, Verlag Chemie GmbH Weinheim Bergstr. 1963, pages 1630-1638</ref></ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div> </div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins class="diffchange diffchange-inline">The compound has been poorly characterized in literature. Most old sources regard it as a derivative of quadrivalent nitrogen, like [[nitrosylsulfuric acid]] (NOHSO<sub>4</sub>) or peroxylaminic acid (NO(SO<sub>2</sub>.OH)<sub>2</sub>). However, its exact formula and even the composition have been debated for a long time. According to more recent investigations it appears that the " acid" is either an oxide of nitrogen intermediate between [[Nitric oxide|NO]] and [[Dinitrogen trioxide|N<sub>2</sub>O<sub>3</sub>]], or a compound of sulfuric acid with such an oxide. On account of this uncertainty the compound is frequently referred to merely as "purple acid" (also "blue acid " and "violet acid").<ref>http://sulphur.atomistry.com/sulphonitronic_acid.html</ref><ref>https://web.archive.org/web/20190330040714/http://sulphur.atomistry.com/sulphonitronic_acid.html</ref> It should be kept in mind, that because the compound is very unstable and has only been made in solution (which thwarts attempts at simple analytical determination), many of the older theories about its structure were only reasoned from sometimes contradictory evidence and othertimes purely from analogy with known compounds based on their color.</ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div> </div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins class="diffchange diffchange-inline">The current (since the 1950s) consensus in the literature is that the purple acid is the salt of the cation N<sub>2</sub>O<sub>2</sub><sup>+</sup>. The argument is based on the following:<ref>F. Seel, B. Ficke, L. Riehl, E. Völkl, Zeitschrift für Naturforschung B 1953, 80, 10, 607-608, [https://doi.org/10.1515/znb-1953-1011 https://doi.org/10.1515/znb-1953-1011]</ref><ref>Gmelins Handbuch der anorganischen Chemie - Schwefel Teil B Lieferung 3, Verlag Chemie GmbH Weinheim Bergstr. 1963, pages 1630-1638</ref></ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins class="diffchange diffchange-inline">*The idea of a molecular compound like some sulfonic acid in the spirit of Frémys salt is incompatible with the observations that reduction of NOClO<sub>4</sub> in 80% HClO<sub>4</sub> with Hg produces the same color.</ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins class="diffchange diffchange-inline">*The idea of a simple adduct of NO and H<sub>2</sub>SO<sub>4</sub> has been attractive, because pressing NO into H<sub>2</sub>SO<sub>4</sub> can form the purple compound, however, on closer inspection it turns out that NO can be oxidized fairly easily in such a solution, producing NOHSO<sub>4</sub>. It seems that NOHSO<sub>4</sub> is essential for the formation.</ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins class="diffchange diffchange-inline">*Similarly adducts of NO with strong Lewis acids are known, such as with HCl, BF<sub>3</sub> and SO<sub>3</sub>.</ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins class="diffchange diffchange-inline">*Raman studies of N<sub>2</sub>O<sub>3</sub><sup>+</sup> are in agreement with the proposed bonding.</ins></div></td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins class="diffchange diffchange-inline">*Similar compounds have been obtained by pressing NO into NOAlCl<sub>4</sub> and NOSbCl<sub>6</sub> in liquid SO<sub>2</sub> (N<sub>2</sub>O<sub>2</sub>AlCl<sub>4</sub> can also be made in NOCl as solvent at high pressures), and both show the characteristic thermochromism of purple acid</ins>.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'>−</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div><del style="font-weight: bold; text-decoration: none;">The compound has been poorly characterized in literature. Most sources regard it as a derivative of quadrivalent nitrogen, like [[nitrosylsulfuric acid]] (NOHSO<sub>4</sub>) or peroxylaminic acid (NO(SO<sub>2</sub>.OH)<sub>2</sub>). However, its exact formula and even the composition is still debated. According to more recent investigations it appears that the " acid" is either an oxide of nitrogen intermediate between [[Nitric oxide|NO]] and [[Dinitrogen trioxide|N<sub>2</sub>O<sub>3</sub>]], or a compound of sulfuric acid with such an oxide. On account of this uncertainty the compound is frequently referred to merely as "purple acid" (also "blue acid " and "violet acid").<ref>http://sulphur.atomistry.com/sulphonitronic_acid.html</ref><ref>https://web.archive.org/web/20190330040714/http://sulphur.atomistry.com/sulphonitronic_acid.html</ref></del></div></td><td colspan="2"> </td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>==Properties==</div></td><td class='diff-marker'> </td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>==Properties==</div></td></tr>
</table>Diachrynichttps://www.sciencemadness.org/smwiki/index.php?title=Purple_acid&diff=13894&oldid=prevMabus: Created page with "{{Chembox | Name = Purple acid | Reference = | IUPACName = | PIN = | SystematicName = | OtherNames = Blue acid<br>Nitrogen oxide nitrosyl hydrogen sulfate<br>Sulphonitronic a..."2021-03-22T19:17:41Z<p>Created page with "{{Chembox | Name = Purple acid | Reference = | IUPACName = | PIN = | SystematicName = | OtherNames = Blue acid<br>Nitrogen oxide nitrosyl hydrogen sulfate<br>Sulphonitronic a..."</p>
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'''Sulfonitronic acid''', '''blue acid''' or more commonly '''purple acid''', is an unstable inorganic compound, which yields a purple solution in [[sulfuric acid]], hence its name. <br />
<br />
The compound has been poorly characterized in literature. Most sources regard it as a derivative of quadrivalent nitrogen, like [[nitrosylsulfuric acid]] (NOHSO<sub>4</sub>) or peroxylaminic acid (NO(SO<sub>2</sub>.OH)<sub>2</sub>). However, its exact formula and even the composition is still debated. According to more recent investigations it appears that the " acid" is either an oxide of nitrogen intermediate between [[Nitric oxide|NO]] and [[Dinitrogen trioxide|N<sub>2</sub>O<sub>3</sub>]], or a compound of sulfuric acid with such an oxide. On account of this uncertainty the compound is frequently referred to merely as "purple acid" (also "blue acid " and "violet acid").<ref>http://sulphur.atomistry.com/sulphonitronic_acid.html</ref><ref>https://web.archive.org/web/20190330040714/http://sulphur.atomistry.com/sulphonitronic_acid.html</ref><br />
<br />
==Properties==<br />
===Chemical===<br />
Purple solution is unstable and decomposes slowly, with formation of sulfuric acid, sulfur dioxide and nitrogen dioxide. When shaken with air or submitted to oxidation by [[chlorine]], [[nitric acid]] or [[hydrogen peroxide]], conversion into [[nitrosylsulfuric acid]] is effected, brown fumes being liberated.<br />
<br />
Dilution with water also destroys the colored compound. If strongly cooled, the solution changes to an intense red, so that if a solution is too weak to possess a marked color at the ordinary temperature, the presence of the "purple acid" can easily be detected by cooling in a mixture of [[acetone]] and [[carbon dioxide|dry ice]].<br />
<br />
Certain of the salts in solution have a stronger color than the free acid, and in some cases are more stable. A deep blue solution of the copper salt may be obtained by the reduction of nitrosylsulfuric acid in sulphuric acid by mercury in the presence of [[copper]]. It has been suggested that the color in the "brown ring" test for a nitrate is due to the formation of the ferrous salt of "purple acid," but this is improbable.<ref>https://www.degruyter.com/document/doi/10.1515/znb-1953-1011/html</ref><br />
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===Physical===<br />
Purple acid is a blue or purple liquid, only stable in sulfuric acid, hence all of its properties are derived from said solution.<br />
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==Availability==<br />
Purple acid is not sold and has to be made in situ.<br />
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==Preparation==<br />
Purple acid can be prepared by passing [[nitrogen dioxide]] with air into a saturated solution of [[sulfur dioxide]] in diluted [[sulfuric acid]] (1:1 by volume) at 0° C. Sulfur dioxide can be easily prepared from [[sodium metabisulfite|sodium]] or [[potassium metabisulfite]], as well as [[sodium sulfite]].<ref>https://www.docdroid.net/xsIwPiK/violet-acid-pdf</ref><br />
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It can also be formed by the addition of [[sodium bisulfite]] to a solution of nitrosylsulfuric acid, which can be produced by dissolving [[sodium nitrite]] in slightly diluted sulfuric acid. These methods depend on the reduction of the nitrosylsulfuric acid by sulfurous acid or sulfur dioxide. The reduction can also be effected by metals, e.g. [[mercury]].<ref>Gmelins Handbuch der anorganischen Chemie - Schwefel Teil B Lieferung 3, Verlag Chemie GmbH Weinheim Bergstr. 1963, pages 1630-1638</ref><br />
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==Projects==<br />
*Chemical demonstrations<br />
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==Handling==<br />
===Safety===<br />
Purple acid is corrosive and unstable.<br />
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===Storage===<br />
Cannot be stored for long. It is only stable in sulfuric acid for a few days under the best conditions.<br />
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===Disposal===<br />
Purple acid can be safely neutralized by diluting it with water and neutralize the resulting acidic solution with a base.<br />
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==References==<br />
<references/><br />
===Relevant Sciencemadness threads===<br />
*[https://www.sciencemadness.org/whisper/viewthread.php?tid=156855 Purple acid, N2O2HSO4]<br />
<br />
[[Category:Chemical compounds]]<br />
[[Category:Inorganic compounds]]<br />
[[Category:Nitrosyl compounds]]<br />
[[Category:Acids]]<br />
[[Category:Mineral acids]]<br />
[[Category:Oxidizing agents]]<br />
[[Category:Materials that react with water]]<br />
[[Category:Materials unstable in basic solution]]<br />
[[Category:Materials stable only in solution]]<br />
[[Category:Unstable materials]]</div>Mabus