Hydrogen chloride vapour pressure

Figure 9.4 Hydrogen chloride vapour pressure vs temperature...

II This dual tilling permits the absorption of both acid smd basic vapours which may be evolved. Thus an amine hydrochloride, which has been recrystallised from concentrated hydrochloric acid, may be readily dried in such a desiccator. If concentrated sulphuric acid alone were used, so much hydrogen chloride would be liberated that tlie pressure inside the desiccator would rise considerably, smd the rate of drying would be reduced. With sodium hydroxide present, however, the hydrogen chloride is removed, smd tho water is absorbed in the normal manner by the reagents but largely by the acid. 

Vapour pressure.—The partial press, of hydrogen chloride for aq. soln. of the gas has been measured by F. B. Allan 15 at 18"4°, by R. Gahl at 25°, and by F. Dole-zalek at 30°. If C denotes the number of grams of hydrogen chloride per 1000 grms. 

The method of experiment was to pass hydrogen at a pressure of 5-15 mm. over the heated metal, whereby a definite small amount of the vapour was taken up, and then to introduce small amounts of chlorine. For each molecule of sodium chloride many molecules of hydrogen chloride are formed. The experiments are carried out at a temperature about 50° lower than that where there is an appreciable spontaneous reaction between the hydrogen and chlorine. 

Fig. 13.— Pressure-Temperature Relations Fig. 14.—-Vapour Pressures of Phos-of Mixtures of Phosphine and Hydrogen phonium Chloride.

After 2 hours of holding, the jacket of reactor 4 is filled with vapour (to heat the reactive mixture to 70 °C) for 1 hour at a residual pressure of 200-520 GPa, temperature not exceeding 70 °C and at agitation the released alcohol is distilled. Alcohol vapours are sent through cooler 5 and 7, gas separators 6 and 8 into collector 11. After the excess alcohol has been distilled, the contents of the reactor are sampled to determine the viscosity and hydrogen chloride content in the obtained oligophenylethoxysiloxane. If the analysis is positive, the product is cooled in the reactor to 60 °C and pumped (the pump is not shown in the diagram) into pressure filter 14 to filter off mechanical impurities. After that, it is poured into containers. 

A given amount of liquid can absorb gas only up to the concentration at which the partial pressure of the gas from the solution formed by absorption is equal to its partial pressure in the gas phase. If the partial pressure of the gas from the solution is lower than in the vapour phase, absorption sets in and the rate of absorption, at a given total absorption coefficient, depends on the difference in the partial pressures in the two phases and on the size of the contact surface. From the dependence of the partial pressures of hydrogen chloride on the composition of the hydrochloric acid it follows that the vapour pressure of HC1 from diluted solutions is relatively very low. Therefore, praotically all the hydrogen chloride from the gas phase can be absorbed, as... 

The method was used by von Wartenberg and Albrecht to determine the vapour pressures of salts, which were boiled in a platinum-iridium tube under various pressures. They found that sodium chloride formed a clear non-viscous liquid, boiling freely when heated in a quartz tube by the oxy-hydrogen blowpipe. It has been mentioned ( 10.VIID) that the vapour density of salts was determined by Nernst. 

The vapour pressure.—D. McIntosh and B. D. Steele give for the vap. press, of Liquid hydrogen chloride between the b. and m. p. ... 

Liquid-vapour equilibria in the phosgene-hydrogen chloride system have also been studied in connection with the problems associated with the separation of these two materials during the production of isocyanates. The system has been examined under atmospheric pressure within the range of the boiling points of the materials, ca. 8 to -85 C. The temperature-composition curve is illustrated in Fig. 6.14 [789] it shows large deviations from ideality. 

On being heated, ammonium chloride dissociates into ammonia and hydrogen chloride. Since, in this case, the vapour phase has the same total composition as the solid phase, viz. NH3 + HCl NH4CI, the system consists of only one component existing in two phases it is therefore univariant, and to each temperature there will correspond a definite vapour pressure (dissociation pressure). If, however, excess of one of the products of dissociation be added, the system becomes one of two components. 

I. Two Gaseous Components. II. a). A Gaseous and a Solid Component which can form Compounds. Ammonia compounds of metal chlorides. Formation of oxy-carbonates. Salts with water of crystallisation. Efflorescence. Indefiniteness of the vapour pressure of a hydrate. Suspended transformation. Eange of existence of hydrates. Constancy of vapour pressure and the formation of compounds. II. (6). The Gas is Absorbed BY THE Solid Component and No Compound is Formed. II. ( ). The Gas is Absorbed by the Solid Component and a Compound is also Formed. II. d). Absorption of Gas and Formation of T-wo Partially Miscible Solid Solutions. Palladium and hydrogen. 

The reaction is carried out in the vapour phase in a multi-tubular reactor packed with a catalyst of mercuric chloride on an activated charcoal support. The reaction is highly exothermic and cooling is applied to keep the temperature at 100—180°C. The pressure used is atmospheric. The gases from the reactor are cooled and washed with aqueous sodium hydroxide to remove unreacted hydrogen chloride. The product is then liquefied by cooling to —40°C and pure vinyl chloride is obtained by fractional distillation. Provided pure reactants are used, this preparation of vinyl chloride is clean and easily accomplished. Vinyl chloride is a colourless gas (b.p. —14°C) with a pleasant, sweet odour. It is conveniently handled, under slight pressure, as a liquid, which may be stored without the addition of a polymerization inhibitor. 

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