Question #5dbac

1 Answer
Jun 21, 2015

Strong acids produce a high concentration of ions in water, which are responsible for transporting current.


Pure water has a very low concentration of ions, which arise from the self-ionization of water:
#H_2O harr H^+ + OH^-#
At room temperature, the total ion concentration is only about #2times10^-14M#.

However, dissolving #HCl# in water at only #0.1M# concentration produces #0.2M# total concentration of ions (#H^+ and Cl^-#). It is the movement of ions through the liquid (in response to an applied electric field) that is responsible for the conductivity of water, so even a modest concentration of strong acid can increase the conductivity by many orders of magnitude.

Highly purified water is actually a very poor electrical conductor, but there are usually enough impurities in normal household tap water to be a fairly good conductor.