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Because of its considerable stability, chromia is a commonly used pigment. It was originally called viridian. It is used in paints, inks, and glasses. It is the colorant in "chrome green" and "institutional green." Chromium(III) oxide is a precursor to the magnetic pigment chromium dioxide, by the following reaction: [8] Cr 2 O 3 + 3 CrO 3 → ...
It is a black powder that crystallises in the rock salt structure. [2] Hypophosphites may reduce chromium(III) oxide to chromium(II) oxide: H 3 PO 2 + 2 Cr 2 O 3 → 4 CrO + H 3 PO 4. It is readily oxidized by the atmosphere. CrO is basic, while CrO 3 is acidic, and Cr 2 O 3 is amphoteric. [3]
Chromium(III) can be obtained by dissolving elemental chromium in acids like hydrochloric acid or sulfuric acid, but it can also be formed through the reduction of chromium(VI) by cytochrome c7. [9] The Cr 3+ ion has a similar radius (63 pm) to Al 3+ (radius 50 pm), and they can replace each other in some compounds, such as in chrome alum and alum.
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Many metals (such as zinc, tin, lead, aluminium, and beryllium) form amphoteric oxides or hydroxides. Aluminium oxide (Al 2 O 3) is an example of an amphoteric oxide. Amphoterism depends on the oxidation states of the oxide. Amphoteric oxides include lead(II) oxide and zinc oxide, among many others. [5]
A chemical bond is the association of atoms or ions to form molecules, crystals, and other structures. The bond may result from the electrostatic force between oppositely charged ions as in ionic bonds or through the sharing of electrons as in covalent bonds, or some combination of these effects.
Optical chemical structure recognition (OCSR) is the translation of images that depict chemical structure information into machine-readable formats. [1] It addresses the challenge of translating chemical structures from graphical representations into their corresponding chemical formulas.
Each layer forms by positioning their lypophilic chains to the same side of the layer. The two layers then stack such that their lyphphilic chains touch on the inside and their polar groups are outside facing the surrounding aqueous media. Thus the inside of the bilayer sheet is a non-polar region sandwiched between the two polar sheets. [2]