Chrome orange is a mixed oxide with the chemical formula Pb2CrO5. It can be made by treating a lead(II) salt with an alkaline solution of a chromate or by treating chrome yellow (PbCrO4) with strongly basic solution. [2]
Chrome orange is a mixed oxide with the chemical formula Pb2CrO5. It can be made by treating a lead(II) salt with an alkaline solution of a chromate or by treating chrome yellow (PbCrO4) with strongly basic solution. [2]
Pb2CrO5 can be synthesized with a gas-liquid precipitation process. [3] Changing the pH controls whether PbCrO4 or Pb2CrO5 is created. [3]
Orthorhombic nanocrystals can be selectively synthesized in a facile room temperature solution for Pb2CrO5. [4]
Using a microwave-assisted ionic liquid (MAIL) method, bundle and rod-like nanocrystals of Pb2CrO5 were formed. [5] The bundles look like bundles of straw, secured in the middle. [5] In basic solution, single-crystalline Pb2CrO5 could be formed by heating lead acetate and potassium dichromate with microwave radiation for only 10 minutes at 90 celsius. [5] The MAIL process is simple, fast, and does not employ surfactants. [5] The presence of hydroxide changes the phase that is formed. Using NaOH, monoclinic Pb2CrO5 is formed. [5] The bundle and rod-shaped structures are sensitive to electron beam irradiation, which will turn them into many small particles. [5]
The Gibbs free energy of Pb2CrO5 was determined in 2010 and is given as
ΔfG°mPb2CrO5(s)±0.30/(kJ•mol−1)=-1161.3 +0.4059(T/K) (859≤T/K≤1021). [6]
Visible light activity up to 550 nanometers has been recorded for Pb2CrO5. [7]
In an catalog published c. 1835, Winsor and Newton paint company identify ten synthetic pathways for producing chrome orange, also called deep yellow. [8] Chrome orange is made of PbCrO4 mixed with basic lead chromate (Pb2CrO5). [8] It has been described as a “yellowish red or sometimes a beautiful deep red” in alkaline conditions. [8] A deep yellow can be created using PbCrO4 and lead sulfate. [8] There are ten synthetic methods for preparing deep chrome yellow (that made with Pb2CrO5), which require a chromate source, a basic lead source, additives, and a sulfate source. [8] CrO42- + H2SO4+Pb(Ac)2 • 2Pb(OH)2 → PbCrO4+Pb2CrO5 at a pH of approximately seven is the synthesis. [8]
Controlling the pH was Winsor and Newton’s method for creating pigments from the pale yellow to the deep chrome orange. [8] The resulting product has a high stability to light, which is always coveted by artists and collectors. [8]
The natural mineral crocoite was discovered in 1797 by Louis Vauquelin and chrome orange was synthesized as a pigment for the first time in 1809. [9] Pb2CrO5 is found in mineral form as phoenicochroite, which is a monoclinic, red, translucent mineral found in various places across the world, including Russia, the USA, and Chile. [10]
| Chrome Orange | |
|---|---|
 Color coordinates | |
| Hex triplet | #E73501 |
| sRGB B (r, g, b) | (231, 53, 1) |
| HSV (h, s, v) | (14°, 100%, 91%) |
| CIELChuv (L, C, h) | (51, 147, 16°) |
| Source | ColourLex [11] |
| B: Normalized to [0–255] (byte) | |
Chrome orange can range in color from light to deep orange and is no longer in production as a pigment. [9] It has also been known as Derby red, Persian red, and Victoria red. [9] It was first recorded as a pigment in 1809 and was perfect for some impressionist painters in the nineteenth century. The yellow-orange pigment of the boat in Renoir’s 1879 painting, The Seine at Asnières (The Skiff) at the National Gallery, London. [9] Chrome orange was used extensively in Frederic Leighton's Flaming June (1895; Museo de Arte de Ponce). [1]
Chromium is a chemical element with the symbol Cr and atomic number 24. It is the first element in group 6. It is a steely-grey, lustrous, hard, and brittle transition metal.
Lead(II) nitrate is an inorganic compound with the chemical formula Pb(NO3)2. It commonly occurs as a colourless crystal or white powder and, unlike most other lead(II) salts, is soluble in water.
The term chromic acid is usually used for a mixture made by adding concentrated sulfuric acid to a dichromate, which may contain a variety of compounds, including solid chromium trioxide. This kind of chromic acid may be used as a cleaning mixture for glass. Chromic acid may also refer to the molecular species, H2CrO4 of which the trioxide is the anhydride. Chromic acid features chromium in an oxidation state of +6 (or VI). It is a strong and corrosive oxidising agent.
Chromate salts contain the chromate anion, CrO2−
4. Dichromate salts contain the dichromate anion, Cr
2O2−
7. They are oxyanions of chromium in the +6 oxidation state and are moderately strong oxidizing agents. In an aqueous solution, chromate and dichromate ions can be interconvertible.
Wulfenite is a lead molybdate mineral with the formula PbMoO4. It can be most often found as thin tabular crystals with a bright orange-red to yellow-orange color, sometimes brown, although the color can be highly variable. In its yellow form it is sometimes called "yellow lead ore".
Potassium dichromate, K2Cr2O7, is a common inorganic chemical reagent, most commonly used as an oxidizing agent in various laboratory and industrial applications. As with all hexavalent chromium compounds, it is acutely and chronically harmful to health. It is a crystalline ionic solid with a very bright, red-orange color. The salt is popular in the laboratory because it is not deliquescent, in contrast to the more industrially relevant salt sodium dichromate.
Naples yellow, also called antimony yellow, is an inorganic pigment used in paintings during the period 1700–1850. Colors range from a muted, or earthy, reddish yellow pigment to a bright light yellow. It is the chemical compound lead antimonate (Pb2Sb2O7). Also known as jaune d'antimoine, it is one of the oldest synthetic pigments. The Ancient Egyptians were known to create it.
Chrome yellow is a yellow pigment in paints using monoclinic lead(II) chromate (PbCrO4). It occurs naturally as the mineral crocoite but the mineral ore itself was never used as a pigment for paint. After the French chemist Louis Vauquelin discovered the new element chromium in 1797 lead chromate was synthesized in the laboratory and used as a pigment beginning in the second decade of the nineteenth century.
Crocoite is a mineral consisting of lead chromate, PbCrO4, and crystallizing in the monoclinic crystal system. It is identical in composition with the artificial product chrome yellow used as a paint pigment.
Silver chromate is an inorganic compound with formula Ag2CrO4 which appears as distinctively coloured brown-red crystals. The compound is insoluble and its precipitation is indicative of the reaction between soluble chromate and silver precursor salts (commonly potassium/sodium chromate with silver nitrate). This reaction is important for two uses in the laboratory: in analytical chemistry it constitutes the basis for the Mohr method of argentometry, whereas in neuroscience it is used in the Golgi method of staining neurons for microscopy.
Zinc chromate, ZnCrO4, is a chemical compound containing the chromate anion, appearing as odorless yellow powder or yellow-green crystals, but, when used for coatings, pigments are often added. It is used industrially in chromate conversion coatings, having been developed by the Ford Motor Company in the 1920s.
Lead(II) chromate is the inorganic compound with the formula (PbCrO4). It has a vivid yellow color and is generally insoluble. Two polymorphs of lead chromate are known, orthorhombic and the more stable monoclinic form. Monoclinic lead chromate is used in paints under the name chrome yellow. It occurs also as the mineral crocoite.
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.
Barium chromate, named barium tetraoxochromate(VI) by the IUPAC, is a yellow sand like powder with the formula BaCrO4. It is a known oxidizing agent and produces a green flame when heated, a result of the barium ions.
Chromium(VI) peroxide or chromium oxide peroxide is an unstable compound with the formula CrO5. This compound contains one oxo ligand and two peroxo ligands, making a total of five oxygen atoms per chromium atom.
The Jones oxidation is an organic reaction for the oxidation of primary and secondary alcohols to carboxylic acids and ketones, respectively. It is named after its discoverer, Sir Ewart Jones. The reaction was an early method for the oxidation of alcohols. Its use has subsided because milder, more selective reagents have been developed, e.g. Collins reagent.
A nanosheet is a two-dimensional nanostructure with thickness in a scale ranging from 1 to 100 nm.
Caesium enneabromodibismuthate is an inorganic compound with the formula Cs3Bi2Br9. It is one of the coordination complexes formed by caesium, bismuth and bromine. At room temperature, it is trigonal (P3m1) and it undergoes phase transformation to monoclinic phase (C12/c1) when the temperature is below 96 K.
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