Sulfur electrical conductivity

Lead dioxide is electrically conductive and is formed ia place as the active material of the positive plates of lead-acid storage batteries. Because it is a vigorous oxidizing agent when heated, it is used ia the manufacture of dyes, chemicals, matches (qv), pyrotechnics (qv), and Hquid polysulfide polymers (42) (see Polypous containing sulfur). 

The potassium combines with the sulfur to form potassium sulfate, which condenses as a soHd primarily in the electrostatic precipitator (ESP) or baghouse. The recovered potassium sulfate is then deUvered to a seed regeneration unit where the ash and sulfur are removed, and the potassium, in a sulfur-free form such as formate or carbonate, is recycled to the MHD combustor. It is necessary also to remove anions such as Cf and E which reduce the electrical conductivity of the generator gas flow. These are present in the coal ash in very small and therefore relatively harmless concentrations. As the seed is recycled, however, the concentrations, particularly of CF, tend to build up and to become a serious contaminant unless removed. 

Figures 5 and 6 present the electrical conductivity of sulfuric acid solutions (51,52). For sulfuric acid solutions in the 90—100% H2SO concentration range, the electrical conductivity measurements reported by Reference 52 are beheved to be the best values other conductivity data are also available...

Total acidity and total chlorides can be deterrnined by conventional techniques after hydrolysing a sample. Satisfactory procedures for determining hydrogen chloride and free-sulfiir trioxide are described in the Hterature (18,41). Small amounts of both hydrogen chloride and sulfur trioxide can be found in the same sample because of the equiUbrium nature of the Hquid. Procedures for the direct deterrnination of pyrosulfuryl chloride have also been described (42,43), but are not generally required for routine analysis. Small concentrations of sulfuric acid can be deterrnined by electrical conductivity. 

Arsenic and selenium, which fall directly below phosphorus and sulfur in the periodic table, are of interest for a variety of reasons. Arsenic is a true metalloid. A metallic form, called gray arsenic, has an electrical conductivity approaching that of lead. Another allotrope, yellow arsenic, is distinctly nonmetallic it has the molecular formula As4, analogous to white phosphorus, P4. Selenium is properly classified as a nonmetal, although one of its allotropes has a somewhat metallic appearance and is a semiconductor. Another form of selenium has the molecular formula Se8. analogous to sulfur. 

As a solution of barium hydroxide is mixed with a solution of sulfuric acid, a white precipitate forms and the electrical conductivity decreases markedly. Write equations for the reactions that occur and account for the conductivity change. 

Aluminum, silicon, and sulfur are close together in the same row of the periodic table, yet their electrical conductivities are widely different. Aluminum is a metal silicon has much lower conductivity and is called a semiconductor sulfur has such low conductivity it is called an insulator. Explain these differences in terms of valence orbital occupancy. 

The main criteria for the selection of the current collector material in a central sulfur cell or for the cell case material in a central sodium cell are corrosion resistance to sulfur and sodium polysulfides, good electrical conductivity, and low costs. This cost argument has led to coated materials which have been compared with nickel—chromium alloys (Inconel 600). 

Graphite bisulfates are formed by heating graphite with a mixture of sulfuric and nitric acids. In the reaction, the graphite planes are partially oxidized. There is approximately one positive charge for every 24 carbon atoms, and the HS04 anions are distributed between the planes, (a) What effect is this oxidation likely to have on the electrical conductivity (b) What effect would you expect it to have on the x-ray diffraction pattern observed for this material Refer to Major Technique 3 on x-ray diffraction, which follows this set of exercises. 

Electrical Conductivity of Liquid Sulfur and Sulfur-Phosphorus Mixtures... 

Sulfur vapor consists of a mixture of species that includes S8, S6, S4, and S2 (which like 02 is paramagnetic). Because the S8 molecule is nonpolar, it is soluble in liquids such as CS2 and C6H6. Selenium also consists of cyclic molecules that contain eight atoms, and tellurium is essentially metallic in character. In their vapors, several species are found that contain 2, 6, or 8 atoms. Both are useful as semiconductors, and selenium has been used in rectifiers. Because the electrical conductivity of selenium increases as the intensity of illumination increases, it has been used to operate electrical switches that open or close as a light beam is broken. Selenium was also used in light meters, but other types of meters are now available that are more sensitive. Table 15.1 gives a summary of the properties of the group VIA elements. 

Solutions of hexaphenylethane in liquid sulfur dioxide conduct electricity, suggesting an ionization into triphenylmethyl positive and negative ions. Since the spectrum of triphenylmethide ion was missing from the spectrum of the solution the following equilibrium was postulated ... 

In the following sections, the electrical conductivity, electrochemical activity toward hydrogen oxidation, and the sulfur poisoning behavior of Ni-YSZ cermet anodes will be discussed in detail, together with the effects of various processing procedures and testing conditions. 

Solid-state (topochemical) polymerization of cyclic disulfur dinitride to poly(sulfur nitride) (or polythiazyl), -fSN, occurs on standing at ambient temperature or higher [Banister and Gorrell, 1998 Labes et al., 1979 Ray, 1978]. Disulfur dinitride is obtained by sublimation of tetrasulfur tetranitride. Polythiazyl is a potentially useful material, since it behaves like a metal. It has an electrical conductivity at room temperature about the same order of magnitude as a metal like mercury and is a superconductor at 0.3°C. Polythiazyl also has high light reflectivity and good thermal conductivity. However, it is insoluble and infusible, which prevents its practical utilization. 

Severe hydroprocessing required to produce ultra-low sulfur fuel removes most of the polar organic compounds from the fuel. The resulting product is virtually unable to effectively dissipate static charge as it builds in moving fuel. Instead, electrical discharge into pockets of gas within a pipeline or into air and vapors as fuel is being dispensed can occur. An explosion may result. Low levels of a fuel-soluble electrical conductivity improver to ultra-low sulfur fuel can help restore fuel electrical conductivity to safe levels. 

Hauver concluded that pressure-time measurements with a sulfur transducer in contact with detonating Baratol gave clear evidence of an initial pressure spike, and lends addnl confirmation to the hydro-dynamic theory of deton proposed by von Neumann and others. The sulfur transducer appeared capable of good resolution over that portion of the pressure-time curve corresponding to the reaction zone, and may offer a method for investigating the reaction process Refs 1) S. Joigneau J. Thouvenin, "Electrical Conductivity of Sulfur Under the Action of a Shock Wave , CR 246, 3422-25 (1958) 2) G.E. Hauver,... 

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