(redirected from Chromates)
Also found in: Dictionary, Thesaurus, Medical.


any salt or ester of chromic acid. Simple chromate salts contain the divalent ion, CrO42--, and are orange



any one of a group of salts of chromic acid and isopolychromic acids. The salts of chromic acid, H2CrO4, namely monochromates or simply chromates, are discussed below.

Chromates are stable only in an alkaline medium; upon acidification, they are converted to dichromates. Potassium chromate and sodium chromate are the most important chromates.

Potassium chromate, K2CrO4, is a yellow crystalline substance, with a density of 2.732 g/cm3 and a melting point of 968.3°C. It is readily soluble in water: 62.9 g at 20°C and 79.2 g at 100°C in 100 g of water. It is produced by the action of potassium hydroxide, KOH, on potassium dichromate, K2Cr2O7.

Sodium chromate, Na2CrO4, is also a yellow crystalline substance, with a density of 2.72 g/cm3 and a melting point of 790°C. A hygroscopic compound, it is soluble in water: 80.2 g in 100 g of water at 19.5°C. It is produced by roasting the natural chromite FeCr2O4 with dolomite and sodium carbonate at 1150°–1200°C, then leaching out Na2CrO4 from the sintered mass formed, and finally subjecting the solution to evaporation and crystallization.

Sodium chromate and potassium chromate are used as chemical reagents, as mordants for dyeing textiles, and as components of tanning solutions in the leather industry. They are also used for seed treatment and as wood preservatives.


Pozin. M. E. Tekhnologiia mineral’nykh solei, 4th ed., parts 1–2. Leningrad, 1974.



(inorganic chemistry)
An ion derived from the unstable acid H2CrO4.
A salt or ester of chromic acid.
A mineral characterized by the cation CrO42-.


To coat a metal surface with a rust-inhibiting primer of lead or zinc chromate.
References in periodicals archive ?
In the field of aerospace paints, S6 Strontium Chromate (SrCrO6) is of great importance as it is the main corrosion inhibiting pigment used in primers approved for the manufacture of primary metallic structures.
As they age, the small lead chromate particles are completely reduced to chromium oxide, while larger ones maintain a core of lead chromate that is coated in a shell of chromium oxide.
The move to phase out lead chromates is a landmark one as it seeks to stop the use of a toxic compound and replace it with a component that is safer to use but with the same, albeit, even more benefits to be gained," he said.
OBJECTIVES: In this study we investigated the lung injury, inflammation, proliferation, and survival signaling responses after repetitive exposure to particulate chromate.
Key words Chromate--chromium--chromosome instability--epigenetic changes--genomic instability--hexavalent chromium--lead chromate--mutations--zinc chromate
Inorganic pigments include ultramarine blues, conventional and encapsulated lead chromates, mixed-metal oxides, aluminum pastes, titanium dioxide, specialty blacks, and chromium oxide green.
There is now a worldwide push on to remove chromates because they are carcinogens," said Sze Yang, a professor of chemistry at the University of Rhode Island and one of the inventors of the polymer.
DCC plans to develop its new Venezuelan site as a supply center for azo organic pigments and lead chromates for all South American markets.
Because it has been recently learned that certain microbacterium degrades piping and condenser systems that no longer use chromates, the firm has had to replace piping systems in several fairly new buildings.
The chromates (a family of compounds containing chromium) often produce contact dermatitis.