Sorry if this is an obvious question.

I am told water dissociates, one product of which is negatively charged hydroxyl ions. This makes sense, but then why doesn't pure water conduct electricity? Surely the hydroxyl ions could act as charge carriers to allow current to pass through the solution?


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    $\begingroup$ Pure water does conduct but it has a very low conductivity. $\endgroup$ – MaxW Sep 26 '20 at 9:10
  • $\begingroup$ Presumably due to the low ionisation of water? Is there a certain amount of conductivity below which we say something doesn't conduct? @MaxW $\endgroup$ – Controller Sep 26 '20 at 9:12
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    $\begingroup$ LOL - Well in capacitors the conductance is so low that it is called "leakage" not "conductance." $\endgroup$ – MaxW Sep 26 '20 at 9:14
  • $\begingroup$ Pure water does conduct inasmuch as it dissociates. $\endgroup$ – Ivan Neretin Sep 26 '20 at 9:44
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    $\begingroup$ Does this answer your question? Why can't pure water conduct electricity since it can be reduced at cathode and oxidised at anode? $\endgroup$ – Mithoron Sep 26 '20 at 16:07

Pure water does conduct as pointed out by the above comments. But it has very less dissociation hence there are very few ions to conduct electricity.

you may have heard that $pH$ of pure water is 7. This statement implies that the concentration of H+ ion is $10^{-7}$. Since it is a neutral solution concentration of $\ce{OH^{-}}$ ion is also $10^{-7}$. As such the conducting property of water is very less.


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