Evaporation-to-completion

Step 2. Determine the vapor pressure in the evaporator. According to the phase rule, for a mixture of two components (propane and butane) it is necessary to establish two variables of the liquid-vapor system in the evaporator to completely define the system and fix the value of all other variables. The assumed liquid mol fraction and a temperature of 0°F is known. The... 

Malonic Acid. 100 g of powdered chloroacetic acid is treated with 150 g of broken ice and dissolved in 125 g of caustic soda (33 A%) solution. The solution should be made exactly neutral, if it is not already (this refers to the mixture). After neutralizing, add 69 g of 98% potassium cyanide in 130 g of water, which has been warmed to 40°. An hour after the addition, the mixture is slowly warmed to 100° and held at this temp for an hour. Cool slowly to 25° and add another 125 g of SSV4% caustic soda solution. Slowly heat the mixture to 100° and hold at that temp until no more ammonia is evolved (2 to 3 hours). To test add sodium hydrate solution to a sample and boil. If no ammonia evolves, then the reaction is complete. When the reaction is complete, the solution is cooled, acidified with dilute HCl acid, and carefully evaporated to complete dryness on a water bath. The residue is powdered, extracted repeatedly with ether, and the ether... 

A second crop of crystals may be obtained as follows. The combined mother liquor and washings are evaporated to complete dryness at reduced pressure, and the residue is dissolved in petroleum ether (50-100 mL) under an atmosphere of ethylene. This solution is filtered through a short column of alumina (2X5 cm), under ethylene, into a round-bottomed flask. Evaporating the solvent to a small volume gives the second crop of Pt(C2H4)2P(C6H,1)3 combined yield 4.2 g (85%). 

To a solution of 122 g. of pure salicylaldehyde (Note 1) in 1000 cc. of normal sodium hydroxide solution at room temperature, is added 1420 g. of 3 per cent hydrogen peroxide. The mixture darkens slightly in color and the temperature rises to 45-50°. The solution is allowed to stand for fifteen to twenty hours, whereupon a few drops of acetic acid are added in order to neutralize any excess alkali, and the solution evaporated to complete dryness on the water bath under reduced pressure. 

A closed circuit of propane is employed for indirect recovery of power from the thermal energy of the hot pyrolyzate of an ethylene plant. The propane is evaporated at 500 psig, and then expanded to 100°F and 190 psig in a turbine where the power is recovered. Then the propane is condensed and pumped back to the evaporator to complete the cycle. Since expansion turbines are expensive machines even in small sizes, the process is not economical on the scale of this example, but may be on a much larger scale. 

The combined filtrate and washings are evaporated to complete dryness. The residue is placed in an oven at 120°C. for 4 hours and is then dissolved in 15 ml. of hot water. Twelve milliliters of absolute ethanol is added to the solution, and the mixture is boiled until a clear solution has formed. The brownish solution is allowed to stand for 2 hours before cooling in ice. The precipitate is filtered, washed successively with 10-ml. portions of 60, 80, and 96% ethanol, and dried in air. The yield is approximately 9 g. 

Step 18. Add 10 mL of concentrated HN03 to the residue. Swirl and evaporate almost to dryness. Cool. Repeat the HN03 evaporation to complete the destruction of the organic material. Remove beaker from the hot plate. 

Then the surface of the undoped layer must be oxidized. This can be done in two ways (1) The sample can be exposed to air at room temperature for several days to permit the growth of a thin oxide layer and then the oxide thickness can be evaluated according to available data on the oxidation of a-Si H as a function of time, already examined by Ponpon and Bourdon (1982). (2) The oxidation could be obtained by leaving the sample (Abeles et al., 1981 Wronski et al., 1981), at a given temperature (100- 200°C) in a cleaned chamber, in the presence of pure Oz. Finally, a Pd film, whose thickness can range between 80 and 500 A, can be thermally evaporated to complete the procedure. Photolithographic techniques and lift-off procedures can be used to define the catalytic area. Figure 6 shows a schematic of a typical MIS structure with the overall dimensions. 

Experiment 62. — I. Add enough warm water to the flask A to loosen the solid, and pour a portion of the contents into a casserole or evaporating dish. Evaporate to complete dryness slowly over a piece of wire gauze and then heat strongly (in the hood) until all fumes of sulphuric and hydrochloric acids have been driven off. 

This method, also known as the nanoprecipitation method, can be applied to numerous synthetic poly-mers. ° In general, the polymer is dissolved in acetone and the polymer solution is added into water. The acetone is then evaporated to complete the formation of the particles. Surface active agents are usually added to water to ensure the stability of the polymer particles. This easy technique of nanoparticle preparation was scaled up for large batch production. It leads to the formation of nanospheres. Nanocapsules can easily be prepared by the same method just by adding a small amount of an organic oil in the polymer solution.When the polymer solution is poured into the water phase, the oil is dispersed as tiny droplets in the solvent-non-solvent mixture and the polymer precipitates on the oil droplet surface. This method leads to the preparation of oil-containing nanocapsules... 

Plinke [1] described the process of stabilizing spent acid of PETN which, according to the same author contains 80% HNO3 and 0.1 0.3% organic substances. Tlic spent acid is distilled in a circulation evaporator to completely destroy organic substances and to obtain pure nitric acid. To reach the full decomposition of organic impurities, sulphuric acid of 70% II2SO4 is present in the evaporator and remains there to the end of the operation. 

The equipment needed in flash evaporation is comparatively modest, and this method is also suitable for the preparation of amorphous alloy films whose constituents have different vapour pressures. It consists of a single heated filament usually made of molybdenum. Powder of the alloy is fed continuously onto the filament, the temperature of which is sufficiently high for evaporation. No shifts in composition of the alloy occur since all the material is evaporated to completion. Devices for monitoring the vapour flux and the source temperature are not needed. The method is restricted to materials that can be obtained in powdered form. 

The moist hydroxide precipitate is dissolved in the minimum amoiuit of warm glacial acetic acid and evaporated to complete dryness on a sand bath. Basic beryllixim acetate Be40(CH3C00)6... 

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