Sulphur dioxide vapour pressure

Figure 9.11 Sulphur dioxide vapour pressure vs temperature...

Dangerous vapours under pressure should be put on the tube side of a condenser, and a cooling medium like water should be put on shell side. In case of a leak, only water will come out and the accident will not occur (e.g., condenser for ammonia or sulphur dioxide under pressure). 

Substances Hazardous to Health, See also Toxic chemicals, 19, 138, 140 Substitution, 133 Sulphur, 30 Sulphur dioxide first aid, 280, 306 physical properties, 306 physiological properties, 69, 71, 304, 305 precautions, 305, 306 vapour pressure, 305 Suppression, 135 Surface area effects, 50, 199 Symbols for dangerous substances, 446, 452 Synthetic lubricants, 159 Synthetic resins, 172 Systemic poisons, 19, 77... 

Sulphur dioxide is recovered from a smelter gas containing 3.5 per cent by volume of SO2, by scrubbing it with water in a countercurrent absorption tower. The gas is fed into the bottom of the tower, and in the exit gas from the top the SO2 exerts a partial pressure of 1.14 kN/m2. The water fed to the top of the tower is free from SO2, and the exit liquor from the base contains 0.001145 kmol SC /kmol water. The process takes place at 293 K, at which the vapour pressure of water is 2.3 kN/m2. The water flow rate is 0.43 kmol/s. 

To obtain the free aldehyde 25 g. of the aldehyde ammonia are dissolved in 25 c.c. of water, a cooled mixture of water (40 c.c.) and concentrated sulphuric acid (30 c.c.) is added, and the acetaldehyde liberated is distilled from the water bath through a calcium chloride U-tube (gently warmed if the external temperature is low) and through an efficient coil condenser. In order to prevent autoxida-tion of the acetaldehyde the apparatus is filled with carbon dioxide before distillation, and, since the vapour pressure of the aldehyde is high, a slow current of carbon dioxide is passed again, for a short time only, at the end of the distillation. Since acetaldehyde boils at 21° the receiver, which is attached to the condenser by means of a cork stopper, must be well cooled in an ice-salt freezing mixture. 

Physical Properties.—Thionyl chloride is a colourless, refractive liquid, oi density 1-076 at 0° C., with freezing-point —104-5° C.s and boiling-point 79° C.,3 under atmospheric pressure. The vapour badly attacks the mucous membranes and possesses an odour recalling that of sulphur dioxide. Up to 150° C. the vapour density is normal, but above this temperature decomposition sets in, finally causing a value only two-thirds of the normal 4 (see the following). 

Physical Properties.—Sulphuryl chloride is a colourless, fuming liquid, with an extremely pungent odour. Z)2 = 1-6074 ->t " = l-4437. It boils at 69-1° C. at 760 mm. pressure, and freezes at —46° C.5 The vapour density is normal at first, but when the chloride is kept, even at 100° C., its vapour commences to dissociate into sulphur dioxide and chlorine. At 200° C. dissociation is almost complete.6 When dissolved in benzene the substance shows a molecular- weight corresponding with S02C12. At ordinary temperatures the specific heat is 0-233, the latent heat of evaporation 32-4 calories per gram, and the heat of formation from the elements approximately 89,540 calories per gram-molecule.7 The dielectric constant at 20° C. is 8-5. As a solvent, the ebullioscopic constant of sulphuryl chloride has been found to have... 

The vapour pressure5 of sulphur dioxide at 50° C. is only about 8 atmospheres, although at 110° C. it exceeds 30 atmospheres, so that the sealed containing vessels are not likely to be submitted to very great strain so long as care is taken to prevent heating. The critical temperature is 157-50+0-05° C. and the critical pressure 77-79+0-05 atmospheres.6... 

Other compounds, containing sulphur or nitrogen, may be present in some oils (like onion, garlic).Investigations on the solubility of pure essential-oil components in carbon dioxide showed that the separation of terpene hydrocarbons and oxygenated derivatives by fractionated extraction is difficult, since their solubility behaviours and vapour pressures are almost the same. Saturating the CO2 with water as modifier can increase the differences in solubility [78],... 

In view of the difficulty in deciding whether or not the initial tension is that of pure mercury, attempts to deduce the equation of state from measurements of the lowering of surface tension at various vapour pressures are open to doubt. Most workers have abandoned the attempt to do this with ordinary gases.7 Oliphant8 and Bosworth9 have, however, measured directly the amounts of carbon dioxide, sulphur dioxide, water vapour, and hydrogen adsorbed on a stream of freshly formed mercury drops. These were found to adsorb the maximum, final amount of gas in a fraction of a second and this was liberated,... 

References are appended to investigations of the solubility of sodium bromide in organic solvents,2 and to others dealing with such properties of its aqueous solutions as specific heat,3 density,4 refractive index,8 vapour-pressure,6 molecular depression of the freezing-point7 and elevation of the boiling-point,8 electrical constants,9 and the influence of sulphur dioxide on the solubility of the bromide.10... 

Other properties of aqueous solutions investigated are density,3 refractive index,4 molecular elevation of the boiling-point,6 vapour-pressure,6 specific heat,7 and electric conductivity.8 References are also appended to work on the compressibility,9 the solubility in organic solvents10 and sulphurous acid,11 the molecular weight in liquid sulphur dioxide,11 the electric conductivity in acetone12 and dilute alcohol,13 the non-existence of polyiodides,14 isomorphism with potassium iodide,15 and the formation of a double salt with silver iodide.16... 

Ammonium sulphite, (NH4)2S03,Hs.O.—Neutralization of sulphurous acid by ammonia yields a solution from which the normal sulphite can be obtained as monohydrate in the form of prismatic crystals.1 At 120° C. the hydrated salt loses part of its water, and is partly converted into the pyrosulphite.2 It can be sublimed at 150° C. in a current of nitrogen, but the vapour is decomposed into sulphur dioxide, ammonia, and water.2 In the dry state the salt is more susceptible to oxidation than when moist.8 The slow oxidation to ammonium sulphate is much accelerated by keeping the solution alkaline with ammonia, by the presence of oxygen-carriers, and by pressure.4 Its heat of formation in the anhydrous form from its elements is 215-4 Cal.5 At 12° C. it dissolves in its own weight of water, yielding a solution of alkaline reaction. 

Fig. 18.VmJ. Vapour Pressure Curves. Abscissae in degrees C., ordinates vapour pressures in mm. Hg. The substances corresponding with the numbers attached to the curves are 1 ammonia, 2 chlorine, 3 methyl ether, 4 cyanogen, 5 sulphur dioxide, 6 ethyl chloride, 7 isopentane, 8 ethyl ether, 9 pentane, 10 carbon disulphide, 11 ethyl formate,...

With regard to the second type, the vapour pressure of the systems with two liquid phases lies between that of the two single components. An example of this is found in suJplmr dioxide and water. On adding sulphur dioxide to water there is an increase of the total vapour pressure but on adding water to liquid sulphur dioxide, the total vapour pressure is diminished. 

Pressure-Temperature Dia am. —If sulphur dioxide is passed into water at 0°, a solution will be formed and the temperature at which ice can exist in equilibrium with this solution will fall more and more as the concentration of the sulphur dioxide increases. At — 2 6°, however, an eutectic point is reached at which solid hydrate separates out, and the system becomes invariant. The curve AB (Fig. 86), therefore, represents the pressure of the system ice—solution II.— vapour, and B represents the temperature and pressure at which the invariant system ice—hydrate—solution II.— vapour can exist. At this point the temperature is — 2-6°, and the pressure 21-2 cm. If heat is withdrawn from this system, the solution will ultimately solidify to a mixture of ice and hydrate, and there wull be obtained the univariant system ice— hydrate— vapour. The vapour pressure of this system has been determined down to a tern- p perature of — 9 5 , at which temperature the pressure amounts to 15 cm. The pressures for this system are represented by the curve BC. 

Some metallic compounds present in trace level (ppm) in petroleum feed, adsorbed to the active site of the catalyst, act and change the selectivity of the reaction by producing more and more unwanted products. When water vapour is present in the sulphur dioxide-air mixture supplied to a platinum-alumina catalyst, a decrease in oxidation activity occurs. This type of poisoning is due to the effect of wafer on fhe sfrucfure of the alumina carrier and is known as stability poisoning. The resulting increase in diffusional resistance may dramatically increase the Thiele modulus, and reduce the effectiveness factor for the reaction. In extreme cases, the pressure drop through a catalyst bed may also increase dramatically. 

Referring to the 20A h battery cross-section, approximately half of the internal battery volume contains the electrolyte reservoir. The reservoir section consists primarily of a collapsible bellows in which the electrolyte solution is stored during the reserve phase of the battery life-cycle. The reservoir section contains a sufficient quantity of electrolyte solution (a mixture of sulphur dioxide, acetonitrile and the electrolyte salt) to provide the capacity rating of the battery. Surrounding the bellows, between it and the outer battery case, is space that holds a specific amount of Freon. The Freon gas is selected such that its vapour pressure always exceeds that of the electrolyte, thereby providing the... 

An enclosure whose interior is filled with air (without any combustibles) or inert gas, e.g. nitrogen, argon, carbon dioxide or sulphur hexafluoride showing a positive pressure differential to the environmental potentially explosive atmosphere, indicates the very general principle of pressurization. The same concept is applied to clean rooms in semiconductor manufacturing or in pharmaceutical production. Gases, vapours, mist or even dust are prohibited to penetrate into the interior of such a clean room or pressurized enclosure. 

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