The electrolysis of molten salts

Molten halides are liquid electrolytes in many instances, and their decomposition may be canned out in principle to produce the metal and halogen, usually in the gaseous state. The theoretical decomposition voltage, E°, is calculated from the Gibbs energy of formation tlrrough the equation 

A complication of the extension of the electrolysis route for metal production, is that in the case of the alkali metals, there is a significant solubility of the metal which would be produced by electrolysis in the molten chloride. The dissolved metal provides very mobile electrons to the melt, thus reducing the salt resistance, and dissipating the increased current, at a given applied potential, without the production of metal. To describe this phenomenon in 

Current efficiency = (1 /2)(% CO2 in the anode gas) + 50% which yields an average efficiency of 85% 

Another possibility that would reduce the overall process efficiency is the kinetics of C02 formation at the anode. There is some evidence that the first step in the sequence 

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Although the electrolysis of molten salts does not in principle differ from that of aqueous solutions, additional complications are encountered here owing to the problems related to the higher temperatures of operation, the resultant high reactivities of the components, the thermoelectric forces, and the stability of the deposited metals in the molten electrolyte. As a result of this, processes taking place in the melts and at the electrodes cannot be controlled to the same extent as in aqueous or other types of solutions. Considerations pertaining to Faraday s laws have indicated that it would be difficult to prove their applicability to the electrolysis of molten salts, since the current efficiencies obtained are generally too small in such cases. 

Predict the products of the electrolysis of molten salts and aqueous solutions. 

Metallic State. The actinide metals, like the lanthanide metals, are highly electropositive. They can be prepared by the electrolysis of molten salts or by the reduction of a halide with an electropositive metal, such as calcium or barium. Their physical properties are summarized in Table 3. 

The principle possibility of carbon nanotubes generation by the electrolysis of molten salts saturated by carbon dioxide was shown. The method advantage is the apparatus simplicity, ecological cleanness, economy, possibility of control of product structure and morphology by choice of the optimum electrolysis conditions. 

Why is the electrolysis of molten salts much easier to predict in terms of what occurs at the anode and cathode than the electrolysis of aqueous dissolved salts ... 

Because of the high melting points of ionic substances, the electrolysis of molten salts requires very high temperatures. Do we obtain the same products if we electrolyze the aqueous solution of a salt instead of the molten salt Frequently the answer is no because water itself might be oxidized to form O2 or reduced to form H2 rather than the ions of the salt. 

The electrolysis of molten salts is an important industrial process for the production of active metals such as sodium and aluminum. We have more to say about them in Chapter 23, when we discuss how ores are refined into metals. 

Because of the high melting points of ionic substances, the electrolysis of molten salts requires very high temperatures. (Section 11.8) Do we obtain the same... 

What characterizes an electrolytic cell What is an ampere When the current applied to an electrolytic ceU is multiplied by the time in seconds, what quantity is determined How is this quantity converted to moles of electrons required How are moles of electrons required converted to moles of metal plated out What does plating mean How do you predict the cathode and the anode half-reactions in an electrolytic cell Why is the electrolysis of molten salts much easier to predict in terms of what occurs at the anode and cathode than the electrolysis of aqueous dissolved salts What is overvoltage ... 

An electrolytic cell, you may recall, is an electrochemical cell in which an electric current drives an otherwise nonspontaneous reaction. The process of producing a chemical change in an electrolytic cell is called electrolysis. Many important substances, including aluminum and chlorine, are produced commercially by electrolysis. We will begin by looking at the electrolysis of molten salts. 

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