Electrochemistry is the study of the chemical processes that result in the movement of electrons. The movement of electrons is known as electricity which gets generated by movements of the electrons from one element to another element. It is known as an oxidation-reduction reaction.
WHAT IS OXIDATION-REDUCATION REACTION?
A reaction involving a change in the oxidation state of one or more elements is known as a redox reaction. Oxidation state of a substance increases when it loses an electron and it becomes oxidized. Oxidation state of a substance decreases when the substance gains an electron and it becomes reduced.
Reducing agents or reductants get oxidized and the oxidizing agents or oxidants get reduced.
WHAT ARE VOLTAIC CELLS AND GALVANIC CELLS?
Alessandro Volta in 1793 discovered that the production of electricity can be done by placement of different metals on the opposite sides of a wet paper or cloth. He made a battery by placing Ag and Zn on the two sides of a wet cloth with salt. The batteries were called as the voltaic cells.
Galvanic or voltaic cells are the electrochemical cells containing a spontaneous reaction and always acquire a positive charge. The electrical energy that is released during the reaction is used to do the work. Voltaic cells contain two half-cell compartments. The half cell where oxidation occurs is known as anode and the other half-cell when reduction takes place is known as cathode.
The electrons in the voltaic cell flow from negative electrode to the positive electrode i.e. from the anode to the cathode. For the occurrence of an oxidation-reduction reaction, the two substances in the respective half-cell compartments are connected via a closed circuit to allow the flow of electrons from the reducing agent to the oxidizing agent. To maintain the electrical neutrality and for allowing the reaction to continue, a salt bridge is required.
The difference in potential energy between anode and the cathode determines the direction of electronic movement. Movement of electrons take place from areas of higher potential energy to the one with lower potential energy. The potential difference between the two electrode is in the unit of volts. For a voltaic cell, the potential difference is also known as the cell potential or electromotive force.
Cell potential of a voltaic cell depends on the concentrations of the specific reactants and the products along with the temperature of the reaction. Changing the stoichiometric coefficient in the half reaction does not bring any change in the value of the standard potential.