![]() ![]() The reaction starts at 180 °С, becoming self-sustaining at approximately 225 °С. ![]() The phenomenon resembles the eruption of a volcano. Sparks are emitted and an ash-like product is formed. Reactions Tabletop volcanoes and thermal decomposition A few drops of ethanol are added to a small pile of ammonium dichromate ((NH 4) 2Cr 2O 7) and ignited. The ammonium dichromate acts as the photoactive site. Photosensitive films containing PVA, ammonium dichromate, and a phosphor are spin-coated as aqueous slurries in the production of the phosphor raster of television screens and other devices. It is also used as a mordant for dyeing pigments, in manufacturing of alizarin, chrome alum, leather tanning and oil purification. ![]() It has been used in pyrotechnics and in the early days of photography as well as in lithography, as a source of pure nitrogen in the laboratory, and as a catalyst. Each NH +Ĥ centre is surrounded irregularly by eight oxygen atoms at N-O distances ranging from ca. The (NH 4) 2Cr 2O 7 crystal (C2/c, z = 4) contains a single type of ammonium ion, at sites of symmetry C 1(2,3). It is formed by the action of chromic acid on ammonium hydroxide with subsequent crystallisation. It has also been used in pyrotechnics and in the early days of photography.Īt room temperature and pressure, the compound exists as orange, acidic crystals soluble in water and alcohol. However, this demonstration has become unpopular in schools due to the compound's carcinogenic nature. It is a salt consisting of ammonium ions and dichromate ions.Īmmonium dichromate is sometimes known as Vesuvian Fire, because of its use in demonstrations of tabletop "volcanoes". In this compound, as in all chromates and dichromates, chromium is in a +6 oxidation state, commonly known as hexavalent chromium. Ammonium dichromate is an inorganic compound with the formula (NH 4) 2Cr 2O 7. ![]()
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