What is Molten Salt? Molten Salt is a rather dreadful name for an otherwise useful catagory of materials & processes. The term "Molten Salt" is self-descriptive; it is melted salt(s). Another common name is Fused Salt(s). The simplest example of a molten salt would be to heat sodium chloride ("table salt") to a red heat (greater than 801° C, or 1474° F)1 upon which it would melt into a liquid. This liquid is stable, has a heat capacity similar to water (by volume) and flows much like water does. The major differences are the obvious higher temperatures attainable in the molten salt state and when the salt solidifies (freezes) it contracts versus expanding like water. Thus, molten salt freezing in a pipe would not burst the pipe as water would.
    Salts are simple, usually ionic (that is the chemical bonds are a simple ionic type) and stable compounds. The most common example of which is "table salt", or sodium chloride (NaCl). Both sodium and chlorine are notoriously reactive; sodium is one of the most electropositive substances (wants to lose an electron) & chlorine one of the most electronegative (wants to take an electron). These two opposite substances readily join to form stable sodium chloride via a strong ionic bond. The melting point of sodium chloride is 801° C ( 1474° F )2, at which point it becomes a liquid, and thus a "molten salt"