Electrochemical cells and cell reactions;
or Voltaic or Galvanic Cells
In this cell, a chemical reaction produces electrical energy.
In this cell, the electrons being transferred from the reducing agent to the oxidizing agent travel through a wire and thus provide an elctric current.
a electrochemical cell is represented as
Ө Zn|ZnSO-4║CuSO-4|Cu In this symbol additionally On zinc side as it is a cathode a - sign is placed in O (as shown) and on Cu side as it is anode a + sign is placed in O.
Reaction at the electrodes are called half cell reactions as both the elctrodes are kept seperate from physical contact and ion movement only is permitted through salt bridge.
At zinc electrode Zn → Zn^2+ +2e¯ (oxidation)
At Cu electrode: Cu^2+ +2e¯ → Cu (reduction)
Remember OIL RIG Oxidation is loss of electrons, Reduction is gain of electrons.
Anode and Cathode
The electrode at which reduction takes place is called positive electrode (anode).
The electrode at which oxidation takes place is called the negative electrode (cathode)
AC ART COT - Anode redection takes place - Cathode oxidation takes place.