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Why is electricty conducted through salt water?

  1. Apr 10, 2010 #1
    Ok so when I pass electricty through salt water the negative ions move from highly negative area to positive area causing a current? My question is why do the move? Let's say there was Sodium and Chloride ions in water. Can't the chloride ion give an electron to sodium and make the whole solution deionized, why do they choose to move instead?

    Thank you :smile:
  2. jcsd
  3. Apr 10, 2010 #2


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    The simplest reason is that it takes *way* less energy to move ions around than to transfer electrons between oppositely charged ions. This is because many simple ions (like Na+ and Cl-) are stabilized by interactions with water, so they are "happier" (i.e. existing in a lower energy state) as ions than as neutral atoms in water.
  4. Apr 10, 2010 #3
    If that happens, it indicates a chemical reaction. For every chemical reaction to happen, it requires appropriate environment i.e. pressure, temperature and other parameters. Now water being a polar solvent doesn't provide chloride ions appropriate environment to transfer their excess electrons to sodium ions. Instead they remain ionized in a polar solvent like water as the water provides that kind of environment to stay them ionized. After being ionized the anion chloride ions are attracted to the anode connected to the +ve terminal of the battery and cation sodium ions are attracted to the cathode connected to the -ve terminal of the external battery. Then each of them take and leave electrons in the cathode and anode.
  5. Apr 10, 2010 #4
    Thanks for the great replies :smile: I have just one mini question left.

    I can understand how reduction reaction can occur in the catode because they supply electrons at that end, but in the anode what make the ion lose its electrons thanks.
  6. Apr 11, 2010 #5
    The event of losing electrons in anode can be interpreted in terms of the electric field set up by the external battery. As the battery exerts an electric force on the negatively charged chloride ion, its excess electron located loosely in its out most shell is attracted by the electric force . The electric force F= qE accelerates the excess electron of chloride ion to the direction of +ve terminal. Hence, chloride ion leaves electrons in anode.
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