Features of Molten Salts

  Conducts Electricity
    One of the interesting features of molten salts is their ability to conduct electricity. For example, solid sodium chloride (NaCl, or table salt) does not conduct electricity; it is an insulator. If NaCl is placed into water, the mutual attraction both sodium (Na) and chlorine (Cl) have for water molecules cause their bonds to break (dissolving) and form ions (charged atoms or molecules) within the water. These electrically charged ions can conduct electricity if there is a voltage potential (electric field).
To test this, place two electrodes in distilled water & using an ammeter, check to see if there is a current flow when a voltage is applied. There will be virtually no current flowing as water is a very poor conductor of electricity. Add a substance that will dissociate into ions (an "electrolyte"), such as table salt, and current will flow. Furthermore, this current will allow the transfer of ions (movement of ion charge 'packets') so that either the water will be dissociated into its component gases hydrogen and oxygen, or, depending upon the electrolyte, the some of the electrolyte (NaCl, in this case) may be dissociated instead, thereby releasing the gas chlorine; which is how most chlorine gas is produced (electricity is passed through concentrated salt water)
    Molten salts conduct electricity the same way they do when they are dissolved in water; some of the salt molecules are dissociated into ions, which allows the ions to conduct electricity. The "Downs Cell" capitalizes on this conduction of electricity to produce virtually all of the metallic sodium required by industry. Electricity is run through molten sodium chloride (with a little calcium chloride salt added to lower the melting point of the sodium chloride). At one terminal chlorine gas is released (the anode) and at the other (the cathode) liquid sodium.
    Using Electricity to Dissociate (Decompose) Chemicals
    The principle of running electricity through molten salts has been around for quite some time. In fact, the first commercial application of electrolytic molten salt technology was the development of the Hall-Héroult electrolytic process for producing aluminum metal in 1886, but the British chemist Sir Humphry Davy had performed the basic experiment in 1809!3 So, as you can see, molten salt technology has been around for almost 200 years.