[HCL]

We know that the electrolysis of aqueous NaCl in the absence of a membrane results in Hydrogen gas and NaOCl, with no chlorine gas.

With a permeable membrane we get Hydrogen gas, Chlorine and NaOH.

What if I place a metallic plate between the Anode and Cathode such that it is not connected to either of them and not grounded, but is metallic (say copper) so can still conduct electricity?

[Hunter2]

Yes it can, but you will get corrosion on the copper plate, because it will be on one side the new anode, means chloride react with copper and on the other side a new cathode, where you get the hydrogen. At least you have two cell in series