Chlorine gas evolution

Dilute hydrochloric acid Lead (II) acetate or nitrate Cobalt nitrate Mercury Hypochlorites, OCh Yellow coloration, followed by chlorine gas evolution Brown lead (IV) oxide forms upon heating Black precipitate of cobalt (II) hydroxide On shaking slightly acidified solution of a hypochlorite with Hg, a brown precipitate of mercury (II) chloride is formed... 

In brine electrolysis, the pH in the anodic compartment (NaCl) is close to 7 and the oxygen-evolution reaction takes place at a potential (1.23 -0.06 X 7 = +0.81 V), much lower than the potential of the chlorine evolution reaction (+1.36 V). Therefore, only pure oxygen should evolve. However,by using appropriate anode materials (such as carbon), chlorine gas evolution... 

Tin recovery from sludge [28]. In the electrodeposition of tin from a fluoroborate electrolyte, a sludge containing approximately 50% tin is formed. The tin can be recovered by electrodeposition of a leachate of the sludge obtained by reacting with concentrated hydrochloric acid. After dilution of the leachate to give a Sn(IV) ion concentration of 50 g dm , the tin can be electrodeposited onto steel plate in tank elec-trolysers. The anode reaction in this process is chlorine gas evolution which is absorbed in sodium hydroxide solution to form sodium hypochlorite which is used in another part of the plant. Tin is recovered as a 3 mm thick compact deposit with a current efficiency >90%. 

In the case of Type 1 and 11 eutectics the potential window is limited at high potentials by chlorine gas evolution and at low potentials by the metal ion reduction with metal deposition from the melt. Type I eutectics have been prepared using Zn, Sn, Fe, Al, Ge and Cu chlorides. Their reduction potential is shifted towards more electronegative values as the metal halide is closer by Lewis acid. Because the reduction potential is associated with Lewis acidity, the corresponding proportions of metal and quaternary ammonium salts affect the potential window. Type 11 eutectics have been developed in order to extend the range of metals able to be electrodeposited from ionic liquids and Cr electrodeposition with good characteristics has been reported (Abbott et al., 2004 Abbott et al., 2004 Benaben Sottil, 2006). Hydration water plays a significant role on the stability and fluidity of choline chloride based ionic liquids. In this case water behaviour is different compared to the case of aqueous electrolytes and the potential window is limited rather by the metallic species... 

The study of hydrous oxide systems is clearly of interest in many areas of electrochemistry. The unusually high level of activity of hydrous oxide-coated metal anodes for such industrially important reactions as oxygen and chlorine gas evolution... 

Janssen and Hoogland (J3, J4a) made an extensive study of mass transfer during gas evolution at vertical and horizontal electrodes. Hydrogen, oxygen, and chlorine evolution were visually recorded and mass-transfer rates measured. The mass-transfer rate and its dependence on the current density, that is, the gas evolution rate, were found to depend strongly on the nature of the gas evolved and the pH of the electrolytic solution, and only slightly on the position of the electrode. It was concluded that the rate of flow of solution in a thin layer near the electrode, much smaller than the bubble diameter, determines the mass-transfer rate. This flow is affected in turn by the incidence and frequency of bubble formation and detachment. However, in this study the mass-transfer rates could not be correlated with the square root of the free-bubble diameter as in the surface renewal theory proposed by Ibl (18). 

Rapid addition of bromine to the dried solvent to make a 10% solution caused a vigorous reaction with gas evolution. As this happened in a newly installed brightly illuminated fume cupboard lined with a reflective white finish, photocatalysed bromination of the solvent may have been involved, as has been observed in chlorine-ether systems. 

An explosion occurred dining the preparation of iron(III) chloride from iron powder and chlorine gas in a chlorinated pyridine solvent. This was attributed to formation of iron(II) chloride, its interaction with the solvent to give iron(III) chloride, then reduction of the latter by iron to iron(II) chloride. The exotherm and increasing evolution of hydrogen chloride caused the reactor to fail [1]. 

In an individual molten carbamide, the electrode processes are feebly marked at melt decomposition potentials because of its low electrical conductivity. Both electrode processes are accompanied by gas evolution (NH3, CO, C02, N2) and NH2CN (approximately) is formed in melt. In eutectic carbamide-chloride melts electrode processes take place mainly independently of each other. The chlorine must evolve at the anode during the electrolysis of carbamide - alkali metal and ammonium chloride melts, which were revealed in the electrolysis of the carbamide-KCl melt. But in the case of simultaneous oxidation of carbamide and NH4CI, however, a new compound containing N-Cl bond has been found in anode gases instead of chlorine. It is difficult to fully identify this compound by the experimental methods employed in the present work, but it can be definitely stated that... 

Table IV exhibits data recorded for several typical examples tested under conditions described. A nominal 100 ppm active chlorine was selected as an accelerated test of chlorine sensitivity. Over 2000 hours there is a slight measurable decline in rejection with no significant change in flux. The pH of the test solution is typically 7.5-8.5 in order to maintain a reasonably stable concentration of hypochlorite ion. Tests are in progress at an acid pH of 5-6 in a test loop in which the reservoir is not sealed under pressure. Therefore a stable concentration of chlorine is difficult to maintain due to the evolution of chlorine gas. It is possible for a change in the rate of degradation to occur due to a change in chemical mechanism of attack. This will be evaluated in the near term.

Prepd by passing chlorine thru a soln of m-iodosotoluene in chlf. The ortho para isomers decompose with gas evolution at 170—75° 175-78°, respectively, but no mention is made of their exploding Ref Beil 5, 310, 311 313... 

It is obvious that the combustion of a molecule of vanadium with an increasing number of molecules of chlorine is not accompanied by a gradually increasing evolution of heat. The figures show that the formation of vanadium tetrachloride (liquid) from vanadium trichloride (solid) and chlorine (gas) proceeds endothermically ... 

The above discussion suggests two of the common ways of quantifying hydrates in cores (1) low core temperatures as sensed by IR imaging (Ford et al 2003) and (2) gas evolution from pressurized core sampling systems (Pettigrew, 1992). A third method of sensing hydrates is by the use of chlorinity, which may be reliable because unlike the previous two methods, it does not depend upon the volatility of gas evolution from nonpressurized cores, nor the time-temperature history of the water surrounding the core. 

Well logs from Hydrate Ridge indicated acceptably consistent estimates of hydrate occurrence, particularly water saturation, and RAB. Hydrate concentration data from logging tools have been confirmed and quantified by more direct core methods of IR sensing of temperature, gas evolution, and chlorinity decrease. 

If gas evolution takes place, it indicates either that the hypochlorite solution contains free chlorine or has undergone autooxidation or that the viscolizer employed is not satisfactory or not concentrated enough. For the experimental work outlined above, the authors found Difco brand gelatin (Difco Laboratories, Detroit, Mich.) very satisfactory. 

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