Osmium tetroxide

Osmium tetroxide (also osmium(VIII) oxide) is the chemical compound with the formula OsO₄. The compound is noteworthy for its many uses, despite the rarity of osmium. It also has a number of interesting properties, one being that the solid is volatile. The compound is colourless, but most samples appear yellow. This is most likely due to the presence of the impurity OsO₂, which is yellow-brown in colour.

Physical properties

Osmium(VIII) oxide forms monoclinic crystals. It has a characteristic acrid chlorine-like odor. The element name osmium is derived from osme, Greek for odor. OsO₄ is volatile: it sublimes at room temperature. It is soluble in a wide range of organic solvents. It is also moderately soluble in water, with which it reacts reversibly to form osmic acid (see below).Pure osmium(VIII) oxide is probably colourless and it has been suggested that its yellow hue is due to osmium dioxide (OsO₂) impurities. The osmium tetroxide molecule is tetrahedral and therefore non-polar. This nonpolarity helps OsO₄ penetrate charged cell membranes. OsO₄ is 518 times more soluble in carbon tetrachloride than in water.

Osmium dioxide

Osmium dioxide is an inorganic compound with the formula OsO₂. It exists as brown to black crystalline powder, but single crystals are golden and exhibit metallic conductivity. The compound crystallizes in the rutile structural motif, i.e. the connectivity is very similar to that in the mineral rutile.

Preparation

OsO₂ can be obtained by the reaction of osmium with a variety of oxidizing agents, including, sodium chlorate, osmium tetroxide, and nitric oxide at about 600 °C. Using chemical transport, one can obtain large crystals of OsO₂, sized up to 7x5x3 mm³. Single crystals show metallic resistivity of ~15 μΩ cm. Typical transport agent is O
2 via the reversibly formation of volatile OsO₄:

Reactions

OsO₂ does not dissolve in water but is attacked by dilute hydrochloric acid. The crystals have rutile structure. Unlike osmium tetroxide, OsO₂ is not toxic.

References

Bayé

Bayé is a town in the Solenzo Department of Banwa Province in western Burkina Faso. As of 2005 it had a population of 5,478.

References

Coordinates: 12°04′N 4°05′W / 12.067°N 4.083°W / 12.067; -4.083

Bay (shelving)

A bay is a basic unit of library shelving. Bays are book cases about 3 feet (0.9 m) wide. Bays are stuck together in rows. Items are shelved from the top shelf to the bottom shelf in each bay.

Rows consist of a number of bays, either single-sided or double-sided, connected to each other. The standard length of a row is five to six bays, but it is not uncommon to find rows seven bays wide or even wider. In some countries a row is referred to as a 'stack' or a 'range'.

References

Bay (TTC)

Bay is a subway station on the Bloor–Danforth line in Toronto, Canada. It is located in heart of the Yorkville district just north of Bloor Street West on the west side of Bay Street.

The Toronto Transit Commission's Lost Articles Office is located here, where objects lost on TTC property are kept until reclaimed or sold by auction. Wi-fi service is available at this station.

History

Bay Station was opened in 1966 as part of the original segment of the Bloor-Danforth line, from Keele Station in the west to Woodbine Station in the east.

Early plans of the Bloor line, and even some published maps, named this station ‘Yorkville’; the platform signs read ‘BAY’ in large type, with a smaller ‘YORKVILLE’ underneath.

Lower Bay

Below the main platform for Bay Station is an abandoned platform, which was used for only six months in 1966 when the TTC experimentally ran trains whose routes included portions of both the Yonge-University and Bloor-Danforth lines. This abandoned platform is sometimes referred to as Lower Bay by the general public or Bay Lower by the TTC.