Electrolysis aqueous NaCl solution

Explosion Hazards. The electrolysis of aqueous solutions often lead to the formation of gaseous products at both the anode and cathode. Examples are hydrogen and chlorine from electrolysis of NaCl solutions and hydrogen and oxygen from electrolysis of water. The electrode reactions. 

Sonoelectrochemical destruction of dyes has also been investigated. Solutions of the acidic dye Sandolan Yellow have been decolourised by a sonoelectrochemical process in aqueous saline solution using platinum electrodes [42]. The process entails the electrolysis of aqueous NaCl solution which involves the liberation of chlorine at the anode and hydroxide ion at the cathode. The overall cell reaction is ... 

Chlorine (Cl ) and sodium hydroxide (NaOH) are two important chemicals produced by electrolysis. Chlorine and sodium hydroxide are generally among the top ten chemicals produced annually in the United States. The electrolysis of brine or aqueous NaCl solution is used to produce chlorine, sodium hydroxide, and hydrogen (Figure 14.14). The chloride ion in the brine solution is oxidized at the anode, while water is converted at the cathode according to the following reactions ... 

On the other hand, application of alkali metal amalgam permits the slowing down of the reaction of metals with alcohols, which is used in the industrial production of alkali metals alkoxides. Production of NaOR by Mathieson Alkali Works is based, for instance, on the reaction of sodium amalgam (formed as a result of the electrolysis of aqueous NaCl solution with the mercury cathode) with alcohol NaOR ROH is isolated from the solutions. Na residue in the amalgam is hydrolyzed, the obtained mixture is returned to the electrolyz-... 

Fig. 15.1 Temperature influence on the electrolysis product of aqueous NaCl solution...

Finally, a preparation of hydrogen that is of considerable importance is the electrolysis of aqueous NaCl solutions ... 

Figure 21-3 Electrolysis of aqueous NaCl solution. Although several reactions occur at both the anode and the cathode, the net result is the production of H2(g) and NaOH at the cathode and Cl2(g) at the anode. A few drops of phenolphthalein indicator were added to the solution. The solution turns pink at the cathode, where OH ions are formed.

Chlorine gas, CI2, is prepared industrially by the electrolysis of molten NaCl (see Section 19.8) or by the chlor-alkali process, the electrolysis of a concentrated aqueous NaCl solution (called brine). Chlor denotes chlorine and alkali denotes an alkali metal, snch as sodium.) Two of the common cells nsed in the chlor-alkali process are the mercnry cell and the diaphragm cell. In both cells the overall reaction is... 

Both I2 and Bt2 are commercially prepared by oxidation of their halide binary salts from oceans or natural waters, and CI2 can be prepared by electrolyzing aqueous NaCl solutions. Why then is it not possible to prepare F2 by electrolysis of an aqueous NaF solution ... 

Due to the cost of electricity, this reaction is not economically feasible when more than a very small amount of hydrogen is required. However, electrolysis does become economically viable on an industrial scale when the hydrogen is produced as a byproduct of the electrolysis of concentrated aqueous NaCl solutions during the production of NaOH and chlorine. ... 

KCIO3. Not very soluble in water, deposited from chlorate(V) solutions (CI2 plus Ca(OH)2 or electrolysis of aqueous NaCl). On heating gives KCl and KCIO4 but decomposes to KCl at high temperatures. 

As in the case of cyclic voltammetry, the electrolysis cell can be built with a thermostatic jacket to carry out measurements at low temperatures. In this case, the apparatus is of an isothermic type (i.e. the compartment containing the reference electrode is also cooled). In this case the most suitable reference electrode is the silver/silver chloride electrode filled by the same solution that will be used to dissolve the electroactive substance. One cannot use the saturated calomel electrode or the aqueous Ag/AgCl electrode because the KC1 (or NaCl) solution would freeze. 

Large amounts of aqueous sodium hypochlorite (NaOCl) are produced in the chlor-alkali industry (Section 18.12) when the Cl2 gas and aqueous NaOH from the electrolysis of aqueous NaCl are allowed to mix. Aqueous NaOCl is a strong oxidizing agent and is sold in a 5% solution as chlorine bleach. 

Generated by electrolysis of aqueous NaCl to produce electrolyzed basic solution at cathode and electrolyzed acidic solution at anode... 

The properties of sodium hydroxide and potassium hydroxide are very similar. These hydroxides are prepared by the electrolysis of aqueous NaCl and KCl solutions (see Section 19.8) both hydroxides are strong bases and very soluble in water. Sodium hydroxide is used in the manufacture of soap and many organic and inorganic compounds. Potassium hydroxide is used as an electrolyte in some storage batteries, and aqueous potassium hydroxide is used to remove carbon dioxide and sulfur dioxide from air. 

Using gas diffusion electrodes, aqueous NaCl- and Na2S04- solutions can be splitted into NaOH and HCl and H2SO4, respectively, at very low electrolysis voltage (resulting only from the ohmic drop and diffusion potentials in the cell) in a three-chamber cell with cation and anion exchange membranes. 

The finding of alkali metal hydroxide inclusions is important both from theoretical interest and from application. A possible consequence could be the isolation of alkali metal hydroxides from their aqueous solutions. Dried solid NaOH and KOH are made in industry by ordinary evaporation of their aqueous solutions obtained by electrolysis of NaCl and KCl, respectively. This method is uneconomical and wastes a lot of energy. On the contrary, the crystal inclusion method is very simple and economical Examples of such isolation processes are given below. 

The benefit of using a membrane in an electrolytic cell can be illustrated in the electrolysis of NaCl. If an aqueous solution of NaCl flows between two electrodes, NaOH forms at the cathode, and cr ions are oxidized to CI2 at the anode by the reaction... 

The cathodic solution prepared by the electrolysis of an NaCl solution showed a strong antioxidant activity on flie aqueous oxidation of polyunsaturated fatty acid esters, squalene, vitamin A and P-carotene. Although the mechanism for the antioxid t effect of the cathodic solution has not been fully elucidated, the effect would be partly due to radical scavenging ability and/or alkaline molecules formed in the cathodic solution. On the other hand, the antioxidant activity of the cathodic solution has not been found on phosphatidylcholine, free fatty acids and a-tocopherol. The different effect of the cathodic solution on the oxidation of polar lipids may be correlated witii the ionization of these lipids in the cathodic solution. 

The hydroxides of the group 1 metals are strong bases because they dissociate to release hydroxide ions in aqueous solution. As we learned in S tion 19-8, sodium hydroxide is produced commercially by the electrolysis of NaCl(aq). Na (aq) goes through the electrolysis unchanged Cl (aq) is oxidized to Cl2(g) and H2O is reduced to H2(g). Potassium hydroxide and lithium hydroxide are made in a similar fashion. Alkali metal hydroxides can also be prepared by the reaction of the group 1 metals with water (equation 21.2). Alkali hydroxides are important in the manufacture of soaps and detergents, describeid later in this section. 

Chlorine and caustic soda are coproducts of electrolysis of aqueous solutions of sodium chloride [7647-14-5] NaCl, (commonly called brine) following the overall chemical reaction... 

It is clear that, if synthetic routes could be devised which would mechanistically hinder disproportionation, such compounds might be preparable. Although univalent compounds of the Group 2 metals have not yet been isolated, there is some evidence for the formation of Mg species during electrolysis with Mg electrodes. Thus H2 is evolved at the anode when an aqueous solution of NaCl is electrolysed and the amount of Mg lost from the anode corresponds to an oxidation state of 1.3. Similarly, when aqueous Na2S04 is electrolysed, the amount of H2 evolved corresponds to the oxidation by water of Mg ions having an average oxidation state of 1.4 ... 

The electrolysis of an aqueous solution of NaCl has the overall equation... 

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