Question

Explain what is observed when an electrolyte $ KCl $ is added to a hydrated ferric oxide solution.

Answer 1

Hint: An electrolyte is a solution which in aqueous form or in molten state dissociates into free mobile ions i.e., cations and anions. Electrolysis is the process of decomposition of an electrolyte by an electric current. Electrolysis takes place in an electrolytic cell which contains a non-conducting vessel and two metal plates known as electrodes which are immersed in the electrolyte through which the current enters and leaves the electrolytic cell.

Complete answer:
The condition for an electrolyte to undergo electrolysis is that the solution should be in equilibrium, that is the number of positive charges should be equal to the number of negative charges in the solution, that is it becomes electrically neutral.
According to electrolysis oxidation and reduction can be described in terms of electrons.
-Oxidation is the loss of electrons.
-Reduction is the gain of electrons.
Reduction happens at the negative cathode because this is where positive ions(cations) gain electrons. Oxidation happens at the positive anode because this is where negative ions(anions) lose electrons.
When $ KCl $ is added to hydrated ferric oxide solution $ \left( {Fe{{\left( {OH} \right)}_3}} \right) $ where it dissociates into $ {K^ + } $ and $ C{l^ - } $ ions. The positively charged colloidal particles of hydrated ferric oxide solution $ \left( {Fe{{\left( {OH} \right)}_3}} \right) $ get coagulated in the presence of negatively charged chloride ions provided by $ KCl $ .

Note:
 $ KCl $ is used in the salt bridge as the transfer number of $ {K^ + } $ and $ C{l^ - } $ ions are almost equal. If the salt bridge is not used then the electrolytes in the electrode will move and start to accumulate, thereby stopping the flow of further electrons, this in turn will stop the working of a cell.