Why does salt water work better than regular water when trying to prooduce an electric current?
kldsflkjsdfkljsadlfk asked:
I am performing an experiment in which you wet your hands, place one on an aluminum plate and one on a copper plate, and it produces an electric current when connected to a DC micrfo ammeter. Wet hands produce more of a current than dry hands because water conducts electricity. Why does salt water work better than plain water? And why does tap water work better than distilled water? I believe both have something to do with ions but I’m not sure. Help me please!
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I am performing an experiment in which you wet your hands, place one on an aluminum plate and one on a copper plate, and it produces an electric current when connected to a DC micrfo ammeter. Wet hands produce more of a current than dry hands because water conducts electricity. Why does salt water work better than plain water? And why does tap water work better than distilled water? I believe both have something to do with ions but I’m not sure. Help me please!
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Abril 14th, 2009 at 7:19
Actually pure water is not a conductor of electricity. It is an insulator. One of the ways to check to see if your water from a distiller or reverse osmosis device is to see that the water conducts very little electricity.
The reason why normal water conducts electricity is that it is not pure. It has dissolved minerals that form ions in the water. These ions are what conduct electricity. It doesn’t take too many ions to make water a good conductor of electricity. This is partly because the ions have a lot of mobility in the liquid.
Salt water conducts electricity better than tap water because, hopefully anyway, salt water has more dissolved ions than your tap water. Tap water conducts electricity better than distilled water for the same reason.
Abril 17th, 2009 at 7:49
Ions have everything to do with it. You answered you own question. There are enough salts on your dry hands to ionize water on your hands to conduct, same as tap water. Distilled water or deionized water, no ions present will not conduct. Sodium and Chloride completely ionize when salt is dissolved in water (salt water) making an excellent conductor.
Abril 18th, 2009 at 23:18
For an electric current to flow, it needs to travel through a medium that has both components of an electric charge, namely, the positive and negative charge.
When electricity flows, it moves from an area of high charge density to lower charge density, because in nature, all systems prefer to move from high density to lower density (aka lower rest state).
In your electric current experiement, you are running a current from your source, lets say, a battery. This source will be your high energy density source and the electricity will be flowing from it to the lower electric density water.
In salt water (where the salt used is, lets say sodium cloride [NaCl] aka table salt) salt molecules dissociate into their respective components (Na+) and (Cl-).
Current must travel from positive to negative, or negative to positive, and the dissociated ions in the water provide this separation of charges through which the electricity can travel.
Pure water, on the other hand, has no such charge separation, therefore, the electricity has a poor medium through which to travel.