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Cr 2 O 3 + 3 CrO 3 → 5 CrO 2 + O 2. Along with many other oxides, it is used as a compound when polishing (also called stropping) the edges of knives, razors, surfaces of optical devices etc. on a piece of leather, balsa, cloth or other material. It is available in powder or wax form, and in this context it is known as "green compound".
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 are rare, but do nevertheless occasionally exist.
Cubic γ-Al 2 O 3 has important technical applications. The so-called β-Al 2 O 3 proved to be NaAl 11 O 17. [18] Molten aluminium oxide near the melting temperature is roughly 2/3 tetrahedral (i.e. 2/3 of the Al are surrounded by 4 oxygen neighbors), and 1/3 5-coordinated, with very little (<5%) octahedral Al-O present. [19]
Its ideal shape anisotropy, which imparts high coercivity and remnant magnetization, made it a compound superior to γ-Fe 2 O 3. Chromium(IV) oxide is used to manufacture magnetic tape used in high-performance audio tape and standard audio cassettes. [89] Chromium(III) oxide (Cr 2 O 3) is a metal polish known as green rouge. [90] [91]
The vast majority of compounds, including all aluminium-containing minerals and all commercially significant aluminium compounds, feature aluminium in the oxidation state 3+. The coordination number of such compounds varies, but generally Al 3+ is either six- or four-coordinate. Almost all compounds of aluminium(III) are colorless. [2]
In acid solution the aquated Cr 3+ ion is produced. Cr 2 O 2− 7 + 14 H + + 6 e − → 2 Cr 3+ + 7 H 2 O ε 0 = 1.33 V. In alkaline solution chromium(III) hydroxide is produced. The redox potential shows that chromates are weaker oxidizing agent in alkaline solution than in acid solution. [6] CrO 2− 4 + 4 H 2 O + 3 e − → Cr(OH) 3 + 5 OH −
Aluminium oxides or aluminum oxides are a group of inorganic compounds with formulas including aluminium (Al) and oxygen (O). Aluminium(I) oxide ( Al 2 O ) Aluminium(II) oxide ( AlO ) (aluminium monoxide)
Chromium(III) oxide, Cr 2 O 3 Chromium dioxide (chromium(IV) oxide), CrO 2 , which includes the hypothetical compound chromium(II) chromate Chromium trioxide (chromium(VI) oxide), CrO 3