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|Section2= |Section3= |Section7= |Section8= }} Ammonium dichromate is the inorganic compound with the formula (NH4)2Cr2O7. In this compound, as in all chromates and dichromates, chromium is in a +6 oxidation state, commonly known as hexavalent chromium. It is a salt consisting of ammonium ions and dichromate ions. Ammonium dichromate is sometimes known as ''Vesuvian Fire'', because of its use in demonstrations of tabletop "volcanoes".〔(【引用サイトリンク】title=Ammonium Dichromate Volcano )〕 However, this demonstration has become unpopular in schools due to the compound's carcinogenic nature. It has also been used in pyrotechnics and in the early days of photography. ==Properties== At room temperature and pressure, the compound exists as orange, acidic crystals soluble in water and alcohol. It is formed by the action of chromic acid on ammonium hydroxide with subsequent crystallisation.〔Richard J. Lewis ''Hawley's Condensed Chemical Dictionary''. Wiley & Sons, Inc: New York, 2007 ISBN 978-0-471-76865-4〕 The (NH4)2Cr2O7 crystal (C2/c, z=4) contains a single type of ammonium ion, at sites of symmetry C1(2,3). Each NH4+ centre is surrounded irregularly by eight oxygen atoms at N—O distances ranging from ca. 2.83 to ca. 3.17 Å, typical of hydrogen bonds. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Ammonium dichromate」の詳細全文を読む スポンサード リンク
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