Polonium sulfates

P0O2 is obtained by direct combination of the elements at 250° or by thermal decomposition of polonium(IV) hydroxide, nitrate, sulfate or selenate. The yellow (low-temperature) fee form has a fluorite lattice it becomes brown when heated and can be sublimed in a stream of O2 at 885°. However, under reduced pressure it decomposes into the elements at almost 500°. There is also a high-temperature, red, tetragonal form. P0O2 is amphoteric, though appreciably more basic than Te02 e.g. it forms the disulfate Po(S04)2 for which no Te analogue is known. 

Hydrazine sulfate is used as a reducing agent in analytical chemistry for gravimetric measurement of nickel, cobalt, and other metals, and in peptide analysis in the separation of polonium from tellurium as an antioxidant in... 

Aqueous 1 M chromium trioxide (12) does not react with metallic polonium, but with polonium(IV) hydroxide or tetrachloride yields an orange-yellow solid, thought to be Po(Cr04)2. This is insoluble in an excess of the reagent and is easily hydrolyzed by water or wet acetone to a dark brown basic chromate with a composition close to 2Po02 Cr()3 (cf., the basic sulfate and selenate). On long standing in an excess of aqueous chromium trioxide, oxidation to polonium(VI) may occur (Section VI,A). 

The white basic selenate, 2Po02Se03, is obtained by treating polonium V) hydroxide or chloride with selenic acid (0.015 iV-5.0 N) the salt is yellow above 250°C and is stable to over 400°C. It is rather less soluble than the basic sulfate, but the solubility increases a hundredfold in passing from 0.05 N to 5 N selenic acid (10), indicating complex ion formation. 

The white basic sulfate, 2Po02-S03, results when polonium(IV) hydroxide or chloride is treated with 0.02 N-0.25 N sulfuric acid. Like the selenate, it is yellow above 250°C and decomposes to the dioxide at 550°C. Solubility studies indicate that it is metastable in contact with 0.1 N-0.5 N sulfuric acid (10). 

These compounds have only been studied on the trace scale. An ether soluble polonium dibenzyl is reported (80, 118) to be formed by the action of dimethylphenylbenzy 1-ammonium chloride on sodium polonide/telluride mixtures in water saturated with hydrogen. The dimethyl was prepared in the same way, but with dimethyl sulfate (118) and may also be formed in... 

The basic salts of quadrivalent polonium, such as the sulfate and sele-nate, show a marked resemblance to those of tellurium and further resemblances appear in the quadrivalent halides, particularly in their complexing with halide ions in solution, while complexing of polonium(IV) with weak acids, such as acetic, oxalic and tartaric, seems to be more marked than is the case with tellurium. 

Evidence for the existence of Po(S04)2 is stronger. The reaction between PoCLt or the hydroxide of polonium with sulfuric acid (0.5-5.0 N) yields a white solid identified as the hydrated solid. The solubility of this material increases with increasing acid concentration, which suggests the formation of anionic sulfate complexes. The white solid loses its water of hydration thermally and leaves a purple solid identified as the anhydrous sulfate. 

The salts 2Po02-X03 (X=S, Se) have been reported to form when the tetrachloride or hydroxide of polonium is treated with more dilute acid (0.02-0.25 N). The basic sulfate is yellow in color, while the selenate is white. 

The method of treatment consisted in effecting a concentration of some of the constituents of the residues and observing the radioactivity of the various portions into which the material was divided. It was observed that if barium was concentrated the radioactivity of that portion increased rapidly. From a ton of residues there may be prepared 10-20 kilograms of crude sulfate whose activity is about 60 times that of uranium. The Curies then converted the sulfates to chlorides and subjected the material to the process of fractional crystallization. After a number of crystallizations there was obtained in the most insoluble portion a fraction, of a gram of radium chloride which was a million times as active as uranium, One ton of pitchblende is said to contain 0.37 gram of radium, 0.00004 gram of polonium,1 and a small amount of aetinium. 

Radioactivity is emitted from atomic nuclei that are unstable and spontaneously change their structure. In 1896, Henri Becquerel first discovered radioactivity when he placed a piece of zinc uranyl sulfate wrapped in paper on a photographic plate. Two years later, Marie and Pierre Curie discovered two highly radioactive elements, polonium and radium, in pitchblende. a particles, the nuclei of helium atoms, were among the radiations emitted by these substances which were spontaneously transmuting. Indeed, since the earth had billions of years ago lost its original complement of light, inert helium, all helium in our... 

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