Tetra Ethyl Lead
Tetraethyllead (commonly styled tetraethyl lead), abbreviated TEL, is an organolead compound with the formula lead, Pb(ethyl group, C2H5)4. It is a fuel additive, first being mixed with gasoline #History, beginning in the 1920s as a patented octane rating booster that allowed Compression ratio, engine compression to be raised substantially. This in turn increased vehicle performance and fuel economy. TEL was first chemical synthesis, synthesised by German chemist Carl Jacob Löwig in 1853. American chemical engineer Thomas Midgley Jr., who was working for General Motors, was the first to discover its effectiveness as an Engine knocking, antiknock agent in 1921, after spending several years attempting to find an antiknock agent, additive that was both highly effective and inexpensive. Concerns were later raised over the toxic effects of lead, especially on children. On cars not designed to operate on leaded gasoline, lead and lead oxides coat the catalyst in catalytic converters, ...
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Parts Per Billion
In science and engineering, the parts-per notation is a set of pseudo-units to describe small values of miscellaneous dimensionless quantities, e.g. mole fraction or mass fraction. Since these fractions are quantity-per-quantity measures, they are pure numbers with no associated units of measurement. Commonly used are parts-per-million (ppm, ), parts-per-billion (ppb, ), parts-per-trillion (ppt, ) and parts-per-quadrillion (ppq, ). This notation is not part of the International System of Units (SI) system and its meaning is ambiguous. Overview Parts-per notation is often used describing dilute solutions in chemistry, for instance, the relative abundance of dissolved minerals or pollutants in water. The quantity "1 ppm" can be used for a mass fraction if a water-borne pollutant is present at one-millionth of a gram per gram of sample solution. When working with aqueous solutions, it is common to assume that the density of water is 1.00 g/mL. Therefore, it is common to equ ...
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