The products of electrolysis of molten NaCl are Na metal and Cl 2 gas, while the products of electrolysis of aqueous solution of NaCl are NaOH, Cl 2 and H 2 .
Please explain this in detail with the appropriate reactions.
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The Electrolysis of Molten NaCl
An idealized cell for the electrolysis of sodium chloride is shown in the figure below. A source of direct current is connected to a pair of inert electrodes immersed in molten sodium chloride. Because the salt has been heated until it melts, the Na+ ions flow toward the negative electrode and the Cl- ions flow toward the positive electrode.
diagram
When Na+ ions collide with the negative electrode, the battery carries a large enough potential to force these ions to pick up electrons to form sodium metal.
Negative electrode (cathode): Na+ + e- ----> Na
Cl- ions that collide with the positive electrode are oxidized to Cl2 gas, which bubbles off at this electrode.
Positive electrode (anode): 2 Cl- ----> Cl2 + 2 e-
The net effect of passing an electric current through the molten salt in this cell is to decompose sodium chloride into its elements, sodium metal and chlorine gas.
Electrolysis of NaCl:
Cathode (-): Na+ + e- ----> Na
Anode (+): 2 Cl- ----> Cl2 + 2 e-
The potential required to oxidize Cl- ions to Cl2 is -1.36 volts and the potential needed to reduce Na+ ions to sodium metal is -2.71 volts. The battery used to drive this reaction must therefore have a potential of at least 4.07 volts.
This example explains why the process is called electrolysis. The suffix -lysis comes from the Greek stem meaning to loosen or split up. Electrolysis literally uses an electric current to split a compound into its elements.
electrolysis
2 NaCl(l) ----> 2 Na(l) + Cl2(g)
This example also illustrates the difference between voltaic cells and electrolytic cells. Voltaic cells use the energy given off in a spontaneous reaction to do electrical work. Electrolytic cells use electrical work as source of energy to drive the reaction in the opposite direction.
The dotted vertical line in the center of the above figure represents a diaphragm that keeps the Cl2 gas produced at the anode from coming into contact with the sodium metal generated at the cathode. The function of this diaphragm can be understood by turning to a more realistic drawing of the commercial Downs cell used to electrolyze sodium chloride
An idealized cell for the electrolysis of sodium chloride is shown in the figure below. A source of direct current is connected to a pair of inert electrodes immersed in molten sodium chloride. Because the salt has been heated until it melts, the Na+ ions flow toward the negative electrode and the Cl- ions flow toward the positive electrode.
diagram
When Na+ ions collide with the negative electrode, the battery carries a large enough potential to force these ions to pick up electrons to form sodium metal.
Negative electrode (cathode): Na+ + e- ----> Na
Cl- ions that collide with the positive electrode are oxidized to Cl2 gas, which bubbles off at this electrode.
Positive electrode (anode): 2 Cl- ----> Cl2 + 2 e-
The net effect of passing an electric current through the molten salt in this cell is to decompose sodium chloride into its elements, sodium metal and chlorine gas.
Electrolysis of NaCl:
Cathode (-): Na+ + e- ----> Na
Anode (+): 2 Cl- ----> Cl2 + 2 e-
The potential required to oxidize Cl- ions to Cl2 is -1.36 volts and the potential needed to reduce Na+ ions to sodium metal is -2.71 volts. The battery used to drive this reaction must therefore have a potential of at least 4.07 volts.
This example explains why the process is called electrolysis. The suffix -lysis comes from the Greek stem meaning to loosen or split up. Electrolysis literally uses an electric current to split a compound into its elements.
electrolysis
2 NaCl(l) ----> 2 Na(l) + Cl2(g)
This example also illustrates the difference between voltaic cells and electrolytic cells. Voltaic cells use the energy given off in a spontaneous reaction to do electrical work. Electrolytic cells use electrical work as source of energy to drive the reaction in the opposite direction.
The dotted vertical line in the center of the above figure represents a diaphragm that keeps the Cl2 gas produced at the anode from coming into contact with the sodium metal generated at the cathode. The function of this diaphragm can be understood by turning to a more realistic drawing of the commercial Downs cell used to electrolyze sodium chloride
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