Uranyl acetate
Encyclopedia
Uranyl acetate is the acetate
salt of uranium
and is a yellow crystalline solid made up of yellow rhombic crystal
s and has a slight acetic odor. Uranyl acetate is slightly radioactive, the precise radioactivity depends on the isotopes of uranium present. This compound is a nuclear fuel
derivative, and its use and possession are sanctioned by international law.
and are prepared by reacting metallic uranium with acetic acid
.
. Most procedures in electron microscopy for biology require the use of uranyl acetate. Negative staining protocols typically treat the sample with 1% to 5% aqueous solution. Uranyl acetate staining is simple and quick to perform and one can examine the sample within a few minutes after staining. Some biological samples are not amenable to uranyl acetate staining and, in these cases, alternative staining techniques and or low-voltage electron microscopy technique may be more suitable.
1% and 2% uranyl acetate solutions are used as an indicator, and a titrant in stronger concentrations in analytical chemistry
, as it forms an insoluble salt with sodium
(the vast majority of sodium salts are water-soluble). Uranyl acetate solutions show evidence of being sensitive to light, especially UV, and will precipitate if exposed.
Uranyl acetate is also used in a standard test—American Association of State Highway and Transportation Officials (AASHTO) Designation T 299—for alkali-silica reactivity
in aggregates (crushed stone or gravel) being considered for use in cement concrete.
Uranyl acetate is very toxic if ingested, inhaled as dust or by skin contact if skin is cut or abraded. The toxicity is due to the combined effect of chemical toxicity and mild radioactivity and there is a danger of cumulative effects from long term exposure.
Acetate
An acetate is a derivative of acetic acid. This term includes salts and esters, as well as the anion found in solution. Most of the approximately 5 billion kilograms of acetic acid produced annually in industry are used in the production of acetates, which usually take the form of polymers. In...
salt of uranium
Uranium
Uranium is a silvery-white metallic chemical element in the actinide series of the periodic table, with atomic number 92. It is assigned the chemical symbol U. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons...
and is a yellow crystalline solid made up of yellow rhombic crystal
Crystal
A crystal or crystalline solid is a solid material whose constituent atoms, molecules, or ions are arranged in an orderly repeating pattern extending in all three spatial dimensions. The scientific study of crystals and crystal formation is known as crystallography...
s and has a slight acetic odor. Uranyl acetate is slightly radioactive, the precise radioactivity depends on the isotopes of uranium present. This compound is a nuclear fuel
Nuclear fuel
Nuclear fuel is a material that can be 'consumed' by fission or fusion to derive nuclear energy. Nuclear fuels are the most dense sources of energy available...
derivative, and its use and possession are sanctioned by international law.
Production
Commercial preparations of uranyl acetate are usually made from depleted uraniumDepleted uranium
Depleted uranium is uranium with a lower content of the fissile isotope U-235 than natural uranium . Uses of DU take advantage of its very high density of 19.1 g/cm3...
and are prepared by reacting metallic uranium with acetic acid
Acetic acid
Acetic acid is an organic compound with the chemical formula CH3CO2H . It is a colourless liquid that when undiluted is also called glacial acetic acid. Acetic acid is the main component of vinegar , and has a distinctive sour taste and pungent smell...
.
Uses
Uranyl acetate is extensively used as a negative stain in electron microscopyElectron microscope
An electron microscope is a type of microscope that uses a beam of electrons to illuminate the specimen and produce a magnified image. Electron microscopes have a greater resolving power than a light-powered optical microscope, because electrons have wavelengths about 100,000 times shorter than...
. Most procedures in electron microscopy for biology require the use of uranyl acetate. Negative staining protocols typically treat the sample with 1% to 5% aqueous solution. Uranyl acetate staining is simple and quick to perform and one can examine the sample within a few minutes after staining. Some biological samples are not amenable to uranyl acetate staining and, in these cases, alternative staining techniques and or low-voltage electron microscopy technique may be more suitable.
1% and 2% uranyl acetate solutions are used as an indicator, and a titrant in stronger concentrations in analytical chemistry
Analytical chemistry
Analytical chemistry is the study of the separation, identification, and quantification of the chemical components of natural and artificial materials. Qualitative analysis gives an indication of the identity of the chemical species in the sample and quantitative analysis determines the amount of...
, as it forms an insoluble salt with sodium
Sodium
Sodium is a chemical element with the symbol Na and atomic number 11. It is a soft, silvery-white, highly reactive metal and is a member of the alkali metals; its only stable isotope is 23Na. It is an abundant element that exists in numerous minerals, most commonly as sodium chloride...
(the vast majority of sodium salts are water-soluble). Uranyl acetate solutions show evidence of being sensitive to light, especially UV, and will precipitate if exposed.
Uranyl acetate is also used in a standard test—American Association of State Highway and Transportation Officials (AASHTO) Designation T 299—for alkali-silica reactivity
Alkali Silica Reaction
The alkali–silica reaction is a reaction which occurs over time in concrete between the highly alkaline cement paste and reactive non-crystalline silica, which is found in many common aggregates....
in aggregates (crushed stone or gravel) being considered for use in cement concrete.
Safety
Uranyl acetate is both radioactive and toxic. Normal commercial stocks prepared from depleted uranium have a typical radioactivity of 0.37 - 0.51 µCi/g. This is a very mild level of radioactivity and is not sufficient to be harmful while the material remains external to the body.Uranyl acetate is very toxic if ingested, inhaled as dust or by skin contact if skin is cut or abraded. The toxicity is due to the combined effect of chemical toxicity and mild radioactivity and there is a danger of cumulative effects from long term exposure.