Hydrochloric Acid - from Gaseous Hydrogen Chloride

9 Hydrochloric Acid - from Gaseous Hydrogen Chloride 

Problem Hydrogen chloride reacts strongly with water and forms hydrochloric acid solution (see E7.8 Tip ) HC1 molecules react by the transfer of protons to H20 molecules and create hydronium ions H30 + (aq) and chloride ions Cl (aq) (see Fig. 7.12). In order to follow this process in an experiment, the colors of universal indicator and the electrical conductivity should be tested and interpreted in this reaction. 

Material Glass bowl, syringe with glass tube, measuring equipment for electrical conductivity and tester hydrogen chloride (see E7.8), water, universal indicator solution. 

Procedure Fill the syringe with hydrogen chloride (see E7.8). Fill a glass bowl up to one third of its volume with tap water, and add indicator solution until it turns green (can be projected with overhead projector). Dip the conductivity 

Observation At first, the green indicator solution shows no electrical conductivity. As soon as hydrogen chloride is released, the conductivity of the solution increases and the indicator color changes from green to red. 

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The hexahydrate of aluminum chloride is a deUquescent, crystalline soHd soluble in water and alcohol and usually made by dissolving aluminum hydroxide [21645-51 -2] A1(0H)2, ia concentrated hydrochloric acid. When the acid is depleted, the solution is cooled to 0 °C and gaseous hydrogen chloride is introduced. Crystalline aluminum chloride hexahydrate, AIQ 6H20, is precipitated, filtered from the Hquor, washed with ethyl ether, and dried. 

In this section, consideration will be given to the actual processes of acetal- or ketal-formation and not to the more indirect methods by which acetals and ketals of the polyhydric alcohols may be synthesized from compounds (e.g. derivatives of the monosaccharides) containing preformed alkylidene or arylidene groupings. The condensation of a carbonyl compound with a glycol is facilitated by acidic catalysts, and, since the reaction is reversible, by dehydration. The catalysts most frequently employed are concentrated sulfuric, hydrochloric and hydro-bromic acids, gaseous hydrogen chloride, zinc chloride and cupric sulfate others are phosphorus pentoxide, sulfosalicylic acid, and anhydrous sodium sulfate. The formation of benzylidene compounds is promoted less efficiently by phosphorus pentoxide than by either concentrated sulfuric acid or concentrated hydrochloric acid 1" the reaction is assisted by chloro- and nitro-substituents on the aromatic nucleus, but hindered by methyl- and methoxy-groups.18... 

One possibility of introducing the concept is the production of gaseous hydrogen chloride from sulfuric acid and common table salt (see E7.8) and subsequent reaction of the produced gas with water to form hydrochloric acid (see E7.9). In the first part, H2S04 molecules donate protons to Cl- ions from sodium chloride crystals to form HC1 molecules and [fSC)4 ions ... 

From the amine with gaseous hydrogen chloride in ether, benzene or chloroform. For directions and examples see Cheronis, p. 601 Shriner, p. 224 Wild, p. 211. From the amine with dilute aqueous hydrochloric acid. 

FIGURE 10.5 The white powder is ammonium chloride formed by gaseous ammonia and hydrogen chloride gas escaping from concentrated hydrochloric acid. 

In this cell, the following independent phases must be considered platinum, silver, gaseous hydrogen, solid silver chloride electrolyte, and an aqueous solution of hydrogen chloride. In order to be able to determine the EMF of the cell, the leads must be made of the same material and thus, to simplify matters, a platinum lead must be connected to the silver electrode. It will be seen in the conclusion to this section that the electromotive force of a cell does not depend on the material from which the leads are made, so that the whole derivation could be carried out with different, e.g. copper, leads. In addition to Cl- and H30+ ions (further written as H+), the solution also contains Ag+ ions in a small concentration corresponding to a saturated solution of silver chloride in hydrochloric acid. Thus, the following scheme of the phases can be written (the parentheses enclose the species present in the given phase) ... 

POLYVINYL CHLORIDE (PVC). [CAS 9002-86-2], The manufacture of polyvinyl chloride resins commences with the monomer, vinyl chloride, which is a gas, shipped and stored under pressure to keep it in a liquid state bp —14°C, fp —160°C, density (20°C), 0.91. The monomer is produced by the reaction of hydrochloric acid with acetylene. This reaction can be carried out in eidier a liquid or gaseous state. In another technique, ethylene is reacted with chlorine to produce ethylene dichloride. This is then cataiytically dehydrohalogcnatcd to produce vinyl chloride. The byproduct is hydrogen chloride. A later process, oxychlorination, permits the regeneration of chlorine from HC1 for recycle to the process. 

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