C. Compounds

Date: 2015-10-07; view: 581.

Uranium tetrafluoride (UF₄) is known as "green salt" and is an intermediate product in the production of uranium hexafluoride. It has the appearance of an emerald-green solid.

Uranium hexafluoride (UF₆) is a colorless crystalline solid which forms a vapor at temperatures above 56.4 °C. UF₆ is the compound of uranium used for the two most common enrichment processes, gaseous diffusion enrichment, and gas centrifuge enrichment. It is simply called "hex" in the industry. It is corrosive to many metals and reacts violently with water and oils.

Yellowcake is purified U-238. It takes its name from the color and texture of the concentrates produced by early mining operations, despite the fact that modern mills using higher calcining temperatures produce "yellowcake" that is dull yellow to almost black. Initially, the compounds formed in yellowcakes were not identified; in 1970, the U.S. Bureau of Mines still referred to yellowcakes as the final precipitate formed in the milling process and considered it to be ammonium diuranate or sodium diuranate. The compositions were variable and depended upon precipitating conditions. Among the compounds identified in yellowcakes include: uranyl hydroxide, uranyl sulfate, sodium para-uranate, and uranyl peroxide, along with various uranium oxides. Modern yellowcake typically contains 70 to 90 percent uranium oxide (U₃O₈) by weight. (Other uranium oxides, such as UO₂ and UO₃, exist; the most stable oxide, U₃O₈, is actually considered to be a 1:2 molar mixture of these.)

Uranium dioxide a dark brown, crystalline powder, once used in the late 1800s to mid-1900s in ceramic glazes is now used mainly as nuclear fuel, specifically in the form of fuel rods.

Uranyl nitrate(UO₂(NO₃)₂) is an extraordinarily toxic, soluble uranium salt. It appears as a yellow crystalline solid.

Uranium rhodium germanium (URhGe) is the first discovered alloy that becomes superconducting in the presence of an extremely strong electromagnetic field.

Uranium carbonate (UO₂(CO₃)) is found in both the mineral and organic fractions of coal and its fly ash and is the main component of uranium in mine tailing seepage water.

Uranium trihydride (UH₃) appears as a black powder, is highly reactive, and pyrophoric.