A current of 1.5 A was passed
through 250 cm3
of 0.5 M AgNO3
aqueous solution for 1 hour and
10 minutes. The anode was platinum,
and the cathode was silver.
(a) Identify the species which
carried the current through
the solution and indicate their
directions of movements.
(b) Give the equations for the
reactions which took place at
the anode and cathode.
(c) Write the changes that would
occur if the platinum anode was
replaced with a silver anode?
(a) The species that carried the current through the solution are the Ag+ ions and the NO3- ions. The Ag+ ions move towards the cathode (positive electrode) and are reduced, while the NO3- ions move towards the anode (negative electrode) and are oxidized.
(b) At the anode (platinum electrode), the oxidation reaction takes place:
2NO3- --> O2 + 2e-
At the cathode (silver electrode), the reduction reaction takes place:
Ag+ + e- --> Ag
(c) If the platinum anode is replaced with a silver anode, the reaction at the anode would change. Instead of the oxidation of NO3- ions, the anode would now undergo the oxidation of silver. The reaction at the anode would be:
2Ag --> 2Ag+ + 2e-