Ammonia over aqueous solutions

Figure 9-76. Partial pressure of ammonia over aqueous solutions of ammonia. Used by permission of Leva, M., Tower Packings and Packed Tower Design, 2nd Ed., U.S. Stoneware Co. (now, Norton Chemical Process Products Corp.) (1953).

Figure 4-2. Equilibrium vapor pressure of ammonia over aqueous solutions. From Perry (1941)...

Equilibrium partial vapor pressures over solutions of the ammonia-sulfur dioxide-water system have been reported by Johnstone (1935). His data cover temperatures from 35° to 90°C as well as concentrations in the range likely to be encountered in a cyclic process in which the solution is regenerated by distillation. Johnstone proposed the following equations to predict the partial pressure of sulfur dioxide and ammonia over aqueous solutions ... 

An ammonia-air mixture (0.02 mole fraction ammonia) is to be scrubbed with water at 20° C. Final mole fraction is 0.00041 ammonia. Both the gas and liquid flow rates are 1.36 x 10 kg/m sec. Equilibrium data for partial pressures of ammonia over aqueous ammonia solutions are ... 

Ammonium Carbamate. Ammonium carbamate is a white crystalline soHd which is soluble ia water (2). It forms at room temperature by passiag ammonia gas over dry ice. In an aqueous solution at room temperature, it is slowly converted to ammonium carbonate, (NH2 2C02, by the... 

Aminoalkoxy pentaerythritols are obtained by reduction of the cyanoethoxy species obtained from the reaction between acrylonitrile, pentaerythritol, and lithium hydroxide in aqueous solution. Hydrogen in toluene over a mthenium catalyst in the presence of ammonia is used (34). The corresponding aminophenoxyalkyl derivatives of pentaerythritol and trimethyl olpropane can also be prepared (35). 

The majority of the cyanuric acid produced commercially is made via pyrolysis of urea [57-13-6] (mp 135°C) primarily employing either directiy or indirectly fired stainless steel rotary kilns. Small amounts of CA are produced by pyrolysis of urea in stirred batch or continuous reactors, over molten tin, or in sulfolane. The feed to the kilns can be either urea soHd, melt, or aqueous solution. Since conversion of urea to CA is endothermic and goes through a plastic stage, heat and mass transport are important process considerations. The kiln operates under slight vacuum. Air is drawn into the kiln to avoid explosive concentrations of ammonia (15—27 mol %). 

Preparation of J-Methy/ Lumilysergic Acid 8-Methyl Ester-10-Methyt Ether into a suspension of 10 grams of 1-methyi-iumiiysergic acid in 600 cc of absoiute methanoi a stream of anhydrous hydrogen chloride is bubbied for 1.5 hours with strong cooiing. The stream of hydrogen chloride is stopped and the mixture is aiiowed to stand for 30 minutes at 0°C, and is evaporated in vacuo to dryness. The residue is taken up with ice-cooied water made aikaiine with concentrated ammonia and extracted with chioroform. The combined chioro-form extracts are washed first with a 5% aqueous solution of sodium bicarbonate, then with water, and are thereafter dried over anhydrous sodium sulfate and finally evaporated in vacuo to dryness. 

About the same time Beutier and Renon (11) also proposed a similar model for the representation of the equilibria in aqueous solutions of weak electrolytes. The vapor was assumed to be an ideal gas and < >a was set equal to unity. Pitzer s method was used for the estimation of the activity coefficients, but, in contrast to Edwards et al. (j)), two ternary parameters in the activity coefficient expression were employed. These were obtained from data on the two-solute systems It was found that the equilibria in the systems NH3+ H2S+H20, NH3+C02+H20 and NH3+S02+H20 could be represented very well up to high concentrations of the ionic species. However, the model was unreliable at high concentrations of undissociated ammonia. Edwards et al. (1 2) have recently proposed a new expression for the representation of the activity coefficients in the NH3+H20 system, over the complete concentration range from pure water to pure NH3. it appears that this area will assume increasing importance and that one must be able to represent activity coefficients in the region of high concentrations of molecular species as well as in dilute solutions. Cruz and Renon (13) have proposed an expression which combines the equations for electrolytes with the non-random two-liquid (NRTL) model for non-electrolytes in order to represent the complete composition range. In a later publication, Cruz and Renon (J4J, this model was applied to the acetic acid-water system. 

When ammonia gas is passed over anhydrous nickel chloride the product is an ammoniate, hexamine nickel chloride, NiCb GNHs. Ammoniate also can be prepared in solution by dissolving nickel chloride hexahydrate in an aqueous solution of ammonia. 

Elemental composition Os 74.82%, 0 25.18%. The compound can be identified by its physical properties, such as, odor, color, density, melting-, and boiling points. Its acrid odor is perceptible at concentrations of 0.02 mg/hter in air. The oxide also produces an orange color when a small amount of the compound or its aqueous solution is mixed with an aqueous solution of ammonia in KOH (see Reactions). Aqueous solution of the tetroxide may be analyzed for osmium by AA or ICP spectrometry (see Osmium). Vapors of the tetroxide may be purged from an aqueous solution by helium, adsorbed over a trap, and desorbed thermally by helium onto a GC. Alternatively, a benzene or carbon tetrachloride solution may be injected onto the GC and the compound peak identified by mass spectrometry. The characteristic mass ions for its identification should be 190 and 254. 

When ammonia gas is passed through an aqueous solution of PdCL, the product is tetrammine palladium(II) chloride, Pd(NH4)2Cl2. The same product also is obtained in dry state by passing ammonia gas over anhydrous PdCL. 

Reaction of Acetoin (3-Hydroxy-2-butanone) with Ammonia. Aqueous solution of ammonium hydroxyde (20%, 100 ml) was added to acetoin (17.6 g, 0.2 mol) and the reaction mixture was stirred for 30 min at 50°C and then for 6 h at room temperature. The precipitated product was filtered off, the filtrate was neutralized with 10% hydrochloric acid, and extracted with ether (continuous overnight extraction). The extract was washed with water, dried over anhydrous sodium sulfate, and concentrated on a spinning-band distillation apparatus. The residual solution was then analyzed by GC and GC-MS. 

The aqueous solution is then steam-distilled from the same flask (Note 6) until no more oil passes over. This usually requires about 6 hours, and 1.5-2 1. of distillate is collected. The phenylacetylene in the distillate is separated and washed several times with distilled water to remove ammonia (Note 7). The washed material is dried over anhydrous magnesium sulfate and distilled through an efficient column (Note 8) under reduced pressure. Almost the entire product distils at 73-74°/80 mm. The yield is 93-106 g. (45-52%) 1.5465-1.5484. 

Sesquiammino-silver Chloride, [Ag2(NH3)3]Cl2, is prepared by allowing ammonia gas to pass over dry powdered silver chloride at a temperature of 20° C. Increase in bulk takes place and ammonia is absorbed. The compound is white in colour, and when exposed to air gradually loses ammonia, leaving, finally, a residue of silver chloride. The same derivative is formed by dissolving precipitated silver chloride in an aqueous solution of ammonia at 20° C. and then cooling the solution to 0° C. or precipitating from solution with alcohol.6 It is... 

---