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CrO 2 was first prepared by Friedrich Wöhler by decomposition of chromyl chloride. Acicular chromium dioxide was first synthesized in 1956 by Norman L. Cox, a chemist at E.I. DuPont, by decomposing chromium trioxide in the presence of water at a temperature of 800 K (527 °C; 980 °F) and a pressure of 200 MPa.
The Pourbaix diagram for chromium in pure water, perchloric acid, or sodium hydroxide [1] [2] Chromium compounds are compounds containing the element chromium (Cr). Chromium is a member of group 6 of the transition metals. The +3 and +6 states occur most commonly within chromium compounds, followed by +2; charges of +1, +4 and +5 for chromium ...
The elements in the group, like those of groups 7–11, have high melting points, and form volatile compounds in higher oxidation states. All the elements of the group are relatively nonreactive metals with a high melting points (1907 °C, 2477 °C, 3422 °C); that of tungsten is the highest of all metals.
The Pourbaix diagram for chromium in pure water, perchloric acid, or sodium hydroxide [27] [28] Chromium is a member of group 6, of the transition metals. The +3 and +6 states occur most commonly within chromium compounds, followed by +2; charges of +1, +4 and +5 for chromium are rare, but do nevertheless occasionally exist. [29] [30]
+4 +6 +8 8 [136] 109 meitnerium: Mt +1 +3 +6 9 [136] 110 darmstadtium: Ds +2 +4 +6 10 [136] 111 roentgenium: Rg −1 +3 +5 11 [136] 112 copernicium: Cn +2 +4 12 [136] 113 nihonium: Nh 13 114 flerovium: Fl 14 115 moscovium: Mc 15 116 livermorium: Lv −2 +4 16 [137] 117 tennessine: Ts −1 +5 17 118 oganesson: Og −1 +1 +2 +4 +6 18 [136] [138 ...
A chemical element, often simply called an element, is a type of atom which has a specific number of protons in its atomic nucleus (i.e., a specific atomic number, or Z). [ 1 ] The definitive visualisation of all 118 elements is the periodic table of the elements , whose history along the principles of the periodic law was one of the founding ...
It can be represented by the chemical formula of Fe Cr 2 O 4. It is an oxide mineral belonging to the spinel group. The element magnesium can substitute for iron in variable amounts as it forms a solid solution with magnesiochromite (Mg Cr 2 O 4). [6] Substitution of the element aluminium can also occur, leading to hercynite (Fe Al 2 O 4). [7]
[3] [4] K 2 Cr 2 O 7 + 6 HCl → 2 CrO 2 Cl 2 + 2 KCl + 3 H 2 O. The sulfuric acid serves as the dehydration agent. It can also be prepared directly by exposing chromium trioxide to anhydrous hydrogen chloride gas. CrO 3 + 2 HCl ⇌ CrO 2 Cl 2 + H 2 O