Electricity, organic compounds

Because it is a saturated aUphatic hydrocarbon, LLDPE does not conduct electricity, and so is widely used for wire and cable insulation. LLDPE is poorly permeable to water and inorganic gases and only slightly more so to organic compounds, whether Hquid or gas. 

In 1990, a test using scrap tires (2x2 in. I DE) to generate steam for electricity was conducted at the Elexsys plant. The I DE replaced 20% of the plant s coal. Results showed that IDE is an environmentally sound fuel. Particulate emissions were reduced by the lower ash content of IDE, volatile organic compounds (VOC) were reduced because of more efficient burning of I DE compared to coal, and carbon dioxide emissions were reduced because I DE contains half the fixed carbon found in coal. Nitrogen oxide, chlorine emissions, and metals were also reduced, and ferrous metals and dioxins were nondetectable (7). 

Resistivity can be used as a guide to the role a material performs ia a specific device. Materials having high values, such as Teflon, serve an iasulation function (see Insulation, electrical). Metals such as silver and copper are excellent conductors. Organic compounds and polymers can cover a wide range of values, and the actual resistivity depends on exact composition. 

Human-made sources cover a wide spectrum of chemical and physical activities and are the major contributors to urban air pollution. Air pollutants in the United States pour out from over 10 million vehicles, the refuse of over 250 million people, the generation of billions of kilowatts of electricity, and the production of innumerable products demanded by eveiyday living. Hundreds of millions of tons of air pollutants are generated annu ly in the United States alone. The five main classes of pollutants are particulates, sulfur dioxide, nitrogen oxides, volatile organic compounds, and carbon monoxide. Total emissions in the United States are summarized by source categoiy for the year 1993 in Table 25-10. 

Polychlorinated biphenyls (PCBs) Highly toxic organic compounds used in the electrical industry, use of w hich is now restricted. 

Many inorganic compounds and all organic compounds also react directly with O2 under appropriate conditions. Reaction may be spontaneous, or may require initiation by heat, light, electric discharge, chemisorption or various catalytic means. Oxygen is normally considered to be divalent, though the oxidation state can vary widely and includes the values of - -i, 0, —j, —j, —I and —2 in isolable compounds of such species as 02", O3, 03 , 02 , 02 and respectively. The coor-... 

Most organic compounds are electrically neutral they have no net charge, either positive or negative. We saw in Section 2.1, however, that certain bonds within a molecule, particularly the bonds in functional groups, are polar. Bond polarity is a consequence of an unsymmetrical electron distribution in a bond and is due to the difference in electronegativity of the bonded atoms. 

The alkali metals also release their valence electrons when they dissolve in liquid ammonia, but the outcome is different. Instead of reducing the ammonia, the electrons occupy cavities formed by groups of NH3 molecules and give ink-blue metal-ammonia solutions (Fig. 14.14). These solutions of solvated electrons (and cations of the metal) are often used to reduce organic compounds. As the metal concentration is increased, the blue gives way to a metallic bronze, and the solutions begin to conduct electricity like liquid metals. 

Silicon, like carbon, is relatively inactive at ordinary temperatures. But, when heated, it reacts vigorously with the halogens (fluorine, chlorine, bromine, cmd iodine) to form halides and with certain metals to form silicides. It is unaffected by all acids except hydrofluoric. At red heat, silicon is attacked by water vapor or by oxygen, forming a surface layer of silicon dioxide. When silicon and carbon are combined at electric furnace temperatures of 2,000 to 2,600 °C (3,600 to 4700 °F), they form silicon carbide (Carborundum = SiC), which is an Importeint abrasive. When reacted with hydrogen, silicon forms a series of hydrides, the silanes. Silicon also forms a series of organic silicon compounds called silicones, when reacted with various organic compounds. 

Because chlorine is more electronegative than carbon, carbon tetrachloride has four polar covalent bonds. But, as pointed out earlier, the molecular symmetry cancels out the electric dipoles of the individual bonds. The result is a nonpolar molecule. Like water, carbon tetrachloride is a good solvent. At one time, it was used as a dry cleaning agent. Water and carbon tetrachloride, however, dissolve entirely different classes of compounds. Carbon tetrachloride forms solutions with nonpolar organic compounds. It is infinitely miscible, for example, with benzene, whereas water and benzene do not mix. 

Kirkpatrick, M.J., Finney, W.C. and Locke, B.R. (2003) Chlorinated organic compound removal by gas phase pulsed streamer corona electrical discharge with reticulated vitreous carbon electrodes, Plasmas and Polymers 8, 165-77. 

Stanley Miller at the University of Chicago more than 50 years ago. This experiment (in fact, of course, many were carried out prior to the successful one) is probably as well known as the Wohler synthesis of urea Miller s doctoral supervisor, Harold Urey (winner of the Nobel Prize in 1934), had suggested to Miller that he simulate a reducing primeval Earth atmosphere (as required by the Oparin-Haldane hypothesis) to electrical discharges and see what happens . Urey apparently expected that such an experiment would lead to a huge variety of organic compounds. 

Organic compounds having four alkyl groups attached to nitrogen. A quaternary ammonium salt is employed in reversing the electric charge on natural rubber latex quaternary ammonium dithiocarbamates are ultra-accelerators for rubber vulcanisation. 

Root exudation and microbial action produce organic compounds with a range of composition and molecular weights. These compounds interact with the mineral particles, which also vary in size, shape, ciystallinity, and electric charge (Emerson et al. 1986). Interactions between soil mineral particles, organic matter and microbes can occur at many different size scales, because these materials have a large size range in soils (Fig. 7). 

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