Why can salt water conduct electricity?

Answer 1

Short Answer:

Salt water does conduct electricity. This is true of all types of salt solutions.

Explanation:

The electrical conductivity of water, both pure water and water with dissolved salts, is simpler to measure than to explain. Conductivity of water does not work like conductivity in a metal. In a metal, the outer electrons of the metal atoms are not tightly bound to specific atoms but rather distributed widely and are pretty much free to move in response to an electric field. When you apply a voltage to a metal you get a large flow of electrons.

In water, the application of a voltage results in the movement of charge, but the charges are not nearly-free electrons but rather ions (charged atoms or molecules). In pure water, the ions that are moving are the protons in the form of H3O+ and hydroxide ions, OH-. In other ionic solutions it is the dissolved ions themselves, for instance in salt water, sodium chloride dissociated into the ions Na+ and Cl-. The same works for other salts.

In some way, the conductivity of an ionic solution is easy to explain. When a voltage is applied, there develops an electric field. Any atom or molecule that has a net charge, q, feel a force, F=qE. Positive ions move in the direction of the field and negative ions move in the opposite direction. Both sets of moving charges add to make a current flows that in the direction of the field.

Of course, one expects that dragging an atom or molecule through a liquid is a lot harder than moving an election through a metal and thus one is not surprised that the conductivity due to ion motion is small. Sea water conducts electric current about a million times better than pure water and drinking water varies depending on the source, but might be a hundred to a thousand time more conductive than pure water. A metal, like gold, copper, aluminum will be a million times better than seawater at conducting electricity while an insulator like glass or rubber is a million times worse than pure water.

Answer 2

Salt water is a pretty good conductor of electricity. Its not as good as a metal, but still, it is far from being an insulator. Pure water does not conduct electricity well at all. Salt water has sodium and chlorine ions in it and because the are charged, they move when you apply a voltage and the moving ions are the actual current.

See related questions for additional explanation.

Answer 3

Short answer:

Salt does not conduct electricity. Salt is an insulator.

We are referring to pure solid salt, as in table salt, as in sodium chloride, as in NaCl crystals.

If you add salt and water together to make salt water, then you get a pretty good conductor in the form of a solution. Sea water or even tap water with a little salt in it conducts reasonably well, though not nearly as good as a metal.

See related questions link for more on the conductivity of salt water.

More:

For any material to be a conductor, electricity must flow when there is a voltage applied. Electricity is current. Current is moving charge.

So, for anything to conduct electricity, there must be some charges in the material that can move.

Metals have a lot of electrons that are not associated with specifc atoms and when a voltage is applied, they feel the electric field and respond quickly and move easily. Metals are thus very good conductors.

An ionic solution, such as salt water, does not have any free electrons, but it does have charged ions, Na+ and Cl-, for example. When a voltage is applied, the ions feel the force of the electric field and the ions move. They are a lot bigger and more massive and move slowly, but they move and so there is a current. So, salt water conducts electricity.

Pure solid crystalline salt has charged atoms. The sodium atoms are nearly stripped of their outer electron to form Na+ and the chlorine atoms form Cl-. But, the difference is, these atoms are locked into position in the crystal of all the sodium chlorine atoms. Each Na+ atom is surrounded by six Cl- atoms and each Cl- atom is surrounded by six Na+ atoms in a cubic crystalline lattice. They vibrate around, but they really don't move out of their crystalline positions. You can apply pretty strong electric fields and still the atoms are so strongly attracted to the neighboring atoms in the crystal that they stay in position and the crystal maintains its regular structure.

To get salt to conduct electricity, you have to destroy the lattice and that is exactly what happens if you dissolve salt in water. It happens if you melt salt too, but that takes a very high temperature.

Answer 4

Salt water conducts electricity because salt water contains positive and negative charges in the form of the ions of the dissolved salt. The current that flows in an ionic solution is the result of the movement of the charged ions. This is fundamentally different than current in a metal where only the electrons move and not the atoms. In an ionic liquid, it is the atoms that move and there is no separate motion of just the electrons.

The force that moves the charged atoms (ions) comes from the electric field created in the liquid by the applied voltage. Usually the voltage is supplied by electrodes immersed in the liquid and connected to an external voltage source such as a battery. The electric field created inside the liquid exerts a force, F=qE, on the ions. Since it is a fluid, the ions can move and so the result is moving charge. Moving charge is electricity.

Answer 5

Short Answer:

Salt water conducts electricity because of the presence of ions in salt water. The ions are charged and they move in response to an electric field that is created when a voltage is applied to the fluid. (This is unlike a metal where current consists of electrons moving.)

Explanation:

Aqueous solutions such as salt water conduct electricity through the movement of ions. If ions exist in any solution to a reasonable extent, it will conduct electricity.

Salt water consist of several ions including Na+, Cl-, H+, OH-. It is the sodium ions (Na+) and the chloride ions (Cl-) that carries out most of the conducting. They are formed via the dissociation of salt (NaCl) in water as demonstrated in the following equation:

NaCl -> Na+ + Cl-

Hydrogen ions (H) and hydroxide ions (OH) are formed by the self ionization of water as demonstrated in the following equation.

H20 <-> H+ + OH-

(The natural dissociation of water into positive and negative ions is small and except for ultra pure water this is a tiny, but real, contribution to the conductivity.)

When a voltage is applied (for instance, by putting positive and negative electrodes in the water), an electric field is created in the salt water. The field exerts a force on the charged ions which will cause the migration of ions in the solution. Moving ions are moving charges. Moving charge is current. Current is electricity. In this way, the salt water conducts electricity.

Answer 6

yes salt water is conductive.