|Why does pure water not conduct electricity?
|Question Date: 2009-05-21|
Electrical current in water consists of the
movement of charged ions in the water. So, for
example, table salt contains two kinds of ions,
positive sodium and negative chlorine. Those ions
will move in response to an electric field if they
are dissolved in water (they won't if they are
locked up in a crystal, though). Pure water
doesn't have many of these ions.
Hydrologists often test the "specific
conductance" of a water sample to see how salty it
is (how much dissolved solids it contains). What
we're really measuring, though, is how that water
is able to conduct an electrical current. When
water contains dissolved solids, those free
electrons can carry an electrical current. When
water is very pure, electricity cannot be
conducted through the water because there are no
ions to carry the charge.
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