Electrolysis of an aqueous sodium chloride solution

An aqueous sodium chloride solution is the most complicated of the three examples of electrolysis considered here because NaCl(a ) contains several species that could be oxidized and reduced. The reductions that might occur at the cathode are 

We can rule out the reduction of Na ion because of the large negative E° value. Under standard-state conditions, the reduction of is more apt to occur than the reduction of H2O. However, in a solution of NaCl, the H concentration is very low, making the reduction of H2O the more probable reaction at the cathode. 

The oxidation reactions that might occur at the anode are 

Keep in mind that in the electrolysis of aqueous solutions, the water Itself may be oxidized and/or reduced. 

the half-cell reactions in the electrolysis of aqueous sodium chloride are 

As the overall reaction shows, the concentration of the Cl ions decreases during electrolysis and that of the OH ions increases. Therefore, in addition to H2 and CI2, the usefid by-product NaOH can be obtained by evaporating the aqueous solution at the end of the electrolysis. 

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During the electrolysis of an aqueous sodium chloride solution elemental chlorine is formed at the anode from the chloride ions, while at the cathode H30 ions are reduced to molecular hydrogen. The area around the cathode contains an aqueous solution of the Na and OH" ions, which determine its basicity and cause the indicator to change color. It is thus possible to generate different color effects in the area around the cathode by changing the indicator used. 

Electrolysis of Molten Sodium Chloride. Electrolysis of Water Electrolysis of an Aqueous Sodium Chloride Solution. Quantitative Aspects of Electrolysis... 

Why does the electrolysis of an aqueous sodium chloride solution produce hydrogen gas at the cathode ... 

The aqueous solution of sodium chlorate(I) is an important liquid bleach and disinfectant. It is produced commercially by the electrolysis of cold aqueous sodium chloride, the anode and cathode products being mixed. The sodium chloride remaining in the solution does not usually matter. There is evidence to suggest that iodic(I) acid has some basic character... 

Sodium hydroxide, sometimes referred to as caustic soda or simply caustic, is produced in enormous quantities by the electrolysis of an aqueous solution of sodium chloride. 

Two other methods for preparing silane are treating sihca gel with aluminum oxide in presence of hydrogen and by electrolysis of an aqueous solution of sodium or ammonium chloride using a sdicon-aluminum ahoy as the positive electrode. 

Ordinary table salt, NaCl, can be electrolyzed in the molten state to produce sodium and chlorine. Electrolysis of an aqueous solution produces sodium hydroxide (NaOH), hydrogen, and chlorine. The latter two products may be combined to form hydrogen chloride (HC1). How many pounds of metallic sodium and of liquid chlorine can be obtained from 1 ton of salt Alternately, how many pounds of NaOH and how many pounds of hydrogen chlorine can be obtained from that sample ... 

Immediately upon connecting the cell to a source of direct current, a deposit of gray metallic zinc appears on the surface of the cathode and bubbles of chlorine gas appear at the surface of the anode. A simple chemical test for chlorine may be made by leading this gas into an aqueous sodium iodide solution, whereupon the solution assumes a yellow color caused by displacement of iodine by chlorine. Accordingly, it is concluded that the products of the electrolysis of a zinc chloride solution are elemental zinc and elemental chlorine, and the next problem is that of explaining the mechanism by which these products may be produced. 

The principle described in this section is very useful, but it must be applied with some caution. For example, in the electrolysis of an aqueous solution of sodium chloride, we should be able to use %° values to predict which products are expected. Of the major species in the solution (Na+, Cl-, and H20), only Cl- and H20 can be readily oxidized. The half-reactions (written as oxidation processes) are ... 

Electrolytic Methods.—Moissan obtained the metal by electrolysis of the double sodium uranium chloride in an atmosphere of hydrogen, using carbon electrodes. Feree, by electrolysis of an aqueous solution of uranous chloride, using a mercury cathode, obtained a uranium amalgam, from which he isolated the uranium by distilling off the mercury in vacuo. However, uranium cannot be obtained in any quantity by this means. 

Electrolysis is employed widely in the manufacture of both metals and chemicals. For instance, the method is used to extract the metals sodium, magnesium and aluminium from their fused salts. In the chemicals industry, one of the largest processes is the electrolysis of an aqueous solution of sodium chloride (brine) for the manufacture of chlorine and caustic soda, i.e.. 

Electrolytic cells represent another type of electrochemical cell. They use an external voltage source to push a reaction in a nonspontaneous direction. The electrolysis of an aqueous solution often involves the oxidation or reduction of water at the electrodes. Electrolysis of concentrated sodium chloride solution, for example, gives hydrogen at the cathode. The amounts of substances released at an electrode are related to the amount of charge passed through the cell. This relationship is stoichiometric and follows from the electrode reactions. 

This question is about the electrolysis of an aqueous solution of liffiium chloride, a Write down the names and S3nnbols of all the ions present in the solution, b Liffiium is a reactive metal, like sodium. What will be formed at the cathode c What will be formed at the anode d Write an equation for the reaction at each electrode. 

An especially useful final product is arsenic. Conceptually the process of metallic arsenic production consists of two stages Lewisite hydrolysis, and electrolysis of arsenious acid in aqueous sodium chloride solution. This method is reliable for Lewisite destruction, and has the virtue of producing arsenic, which is valuable, and suitable for longterm storage. 

When an aqueous salt solution is electrolyzed, the electrode reactions may differ from those for electrolysis of the molten salt because water may be involved. In the electrolysis of aqueous sodium chloride, for example, the cathode half-reaction might be either the reduction of Na+ to sodium metal, as in the case of molten sodium chloride, or the reduction of water to hydrogen gas ... 

One extraction process used industrially on a large scale is the purification of sodium hydroxide for use in the manufacture of rayon. The sodium hydroxide produced by electrolysis typically contains 1% sodium chloride and 0.1% sodium chlorate as impurities. If a concentrated aqueous solution of sodium hydroxide is extracted with liquid ammonia, the NaCl and NaClOs are partitioned into the ammonia phase in preference over the aqueous phase. The heavier aqueous phase is added to the top of an extraction vessel filled with ammonia, and equilibrium is reached as droplets of it settle through the ammonia phase to the bottom. This procedure reduces impurity concentrations in the sodium hydroxide solution to about 0.08% NaCl and 0.0002% NaClOj. 

How is electrolysis of a sodium chloride solution different from electrolysis of molten sodium chloride In molten NaCl, the only ions present are Na+ and CU. What ions are present in an aqueous solution of rock salt Recall that water dissociates slightly to form H+ and OH ions. 

In the chloralkall electrolysis process, an aqueous solution of sodium chloride is decomposed electrolytically by direct current to produce chlorine, hydrogen, and sodium hydroxide according to the following equations ... 

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