common salt conducts electricity only in molten state? why?

Asked by  | 30th Sep, 2012, 08:39: AM

Expert Answer:

In solid table salt (sodium chloride or NaCl), the atoms of sodium and chlorine are locked to each other in ionic bonds, and these molecules are, in turn, locked into a crystal matrix. There are no "free electrons" in this structure that are available to support the flow of electric current. That's why salt in its solid form won't conduct electricity. It's a different story when sodium chloride is in aqueous solution or is molten.

In solution, salt molecules will dissociate. They will "decompose" into ions of sodium and chlorine, what are Na+ and Cl- as we write them in chemistry. These ions have mobility in the solution, and if we stick a pair of electrodes into a salt solution and hook up a battery, we can get current flow through the solution. The ions themselves will be the charge carriers, and salt water is a conductor or an electrolyte.

Answered by  | 30th Sep, 2012, 12:25: PM

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