Oxidation occurs when a reactant loses electrons during the reaction.
Reduction occurs when a reactant gains electrons during the reaction.
Electrons always flow from the anode to the cathode.
The reaction in a galvanic cell is always an oxidation–reduction reaction that can be broken down into two half-reactions.
Remember
The halfreaction with the largest positive potential will run as written (as a reduction), and the other half-reaction will be forced to run in reverse (will be the oxidation reaction).
Anode components are listed on the left and the cathode components are listed on the right, separated by double vertical lines (indicating the salt bridge or porous disk).
Anode | aq || aq | cathode
Fe -> Fe(2+) + 2é [anode]
Ni(2+) + 2é -> Ni [Cathode]
*written from left to right : anode (oxi) to cathode (reduce) {put concentrations for aq solutions ions}
Fe(s) | Fe(2+) || Ni(2+) | Ni(s)
Oxidation state for pure elements is 0
In cell notation if there is two aqueous solutions in a half-reaction, add reactants first then products.
Cations flow towards cathode [viceversa for anode]
