Molten NaCI

Fig. 19-5. Preparation of chlorine and sodium by electrolysis of molten NaCI.

In the electrolysis of molten NaCI, sodium ions move towards the cathode and chloride ions move towards the anode. 

If proper mechanical arrangements are provided, the Na is collected (as a vapor at the temperature of molten NaCI) in the absence of air at the negative electrode, and Cl2 gas is collected at the positive electrode. Different mechanical provisions must be made if the metal is produced as a liquid or a solid, but the principle is the same in every case. If we look at the completed circuit, we see that electrons have come from the power supply to the negative electrode and have gone to the power supply from the positive electrode, with a hi directional flow ofions within the cell. 

Molten NaCI is subjected to electrolysis. What reaction takes place at the cathode ... 

B. The best solvents for a solute have intermolecular bonds of similar strength to the solute ( like dissolves like ). Bromine is a non-polar molecule with intermolecular attractions due to weak London dispersion forces. The relatively strong hydrogen bonding in H20 and NH3 and the very strong electrostatic attractions in molten NaCI would make each of them a poor solvent for Br2 because these molecules would prefer to remain attracted to one another. CS2 is a fairly small non-polar molecule. 

C Reduction (choices B and C) always occurs at the cathode. Molten NaCI is composed of ions in liquid form before electrolysis (answer C). A and D are oxidation reactions, and D is also not properly balanced because a +1 charge is on the left and a -1 charge is on the right. The two half-reactions are ... 

Na Electrolysis of molten NaCI + CaCI2 bcc 0.970 97.8 883 Reducing agent, lamps, nuc. reactors... 

Comparison of Some Properties of Water and Molten NaCI... 

Fig. 5. 33. Plot to show deviations from the Nemst-Ein-stein equation (o) observed equivalent conductivity of molten NaCI and ( ) calculated from Eq. (5.61).

Comparison of the Transport Number of in Molten NaCI Calculated from Equation (5.84) with Measured Values... 

Molten NaCI conducts an electric current, indicating the presence of mobile Na+ and CF ions. 

Electrolysis of molten NaCI Just as electrolysis can decompose water into its elements, it also can separate molten sodium chloride into sodium metal and chlorine gas. This process, the only practical way to obtain elemental sodium, is carried out in a chamber called a Down s cell, as shown in Figure 21-18. The electrolyte in the cell is the molten sodium chloride itself. Remember that ionic compounds can conduct electricity only when their ions are free to move, such as when they are dissolved in water or are in the molten state. 

FIGURE 19.17 (a) A practical arrangement called a Downs cell for the electrolysis of molten NaCI (m.p. = 80rq. The sodium metal formed at the cathodes is in the liquid state. Since liquid sodium metal is lighter than molten NaCI, the sodium floats to the surface, as shown, and is collected. Chlorine gas forms at the anode and is collected at the top. (b) A simplified diagram showing the electrode reactions during the electrolysis of molten NaCI. The battery is needed to drive the nonspontaneous reactions. 

C Reduction (choices B and C) always occurs at the cathode. Molten NaCI is... 

Electrolysis of molten NaCI in a Downs cell is the major isolation step in the production of sodium metal. Assuming that 215 g of Na metal forms,... 

Electrolysis has many important industrial applications. What are some of these applications The electrolysis of molten NaCI is the major process by which sodium metal is produced. However, the electrolysis of aqueous NaCI does not produce sodium metal under normal circumstances. Why What is purification of a metal by electrolysis ... 

Molten beryllium chloride reacts with chloride ion from molten NaCI to form the BeCl4 ion, in which the Be atom attains an octet. Show the net ionic reaction with Lewis structures. 

Ionic Positive and negative ions Ion-ion attraction Hard and brittle, high mp, good thermal and electrical conductors when molten NaCI [801] C aF2 [1423] MgO [2852]... 

The voltammetric curve for molten NaCI-KCI-CrCIa and LiCI-KCI-CrCIa melts are presented in Fig.l and Fig.2. They have two clear, well reproducible peaks, which correspond to the one- and two-electron processes [4] ... 

Molten NaCI, melting point = 801 °C, is a clear, colorless liquid that looks like water. 

The Na metal remains liquid because its melting point Is only 97.8°C. It floats because It Is less dense than the molten NaCI. 

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