Question

What is electrode potential? What are the factors which affect electrode potential?

Answer 1

Hint: In a galvanic cell there are two electrodes anode and cathode. The difference of the potential at these two electrodes calculates the potential across the cell and is termed as EMF of the cell. We use Nernst’s equation to calculate it. The factors affecting the Nernst equation also affect the electrode potential.

Complete step by step answer:
 In electrochemistry, in a galvanic cell there are two electrodes. We refer to one of them as the anode and other as the cathode. The anode is the negative unit and oxidation takes place at the anode and reduction takes place at the cathode and it is the positive section.
The difference between the electrodes gives us the maximum potential difference between the two cells. This potential is termed as the cell potential and it is given by-
     \[{{E}_{cell}}={{E}_{cathode}}-{{E}_{anode}}\]

The value of this electrode potential depends upon certain factors. Let us discuss these factors-
-The electrode potential depends upon the temperature. Depending upon the type of reaction (exothermic or endothermic), the equilibrium of the reaction shifts towards left (or right) if we increase (or decrease) the temperature, thus the electrode potential becomes more negative (or positive).
- The electrode potential depends upon the concentration of the ions present because during writing the Nernst’s equation, we use the concentration of the ions present in the solution-

     \[{{E}_{cell}}={{E}^{\circ }}-\dfrac{RT}{nF}\ln \dfrac{\left[ reduction \right]}{\left[ oxidation \right]}\]
- The electrode potential also depends on the nature of the ions i.e. position in the electrochemical series.
- Increases or decrease in pressure also affects the electrode potential

Note: We consider a hydrogen electrode as the standard electrode and it is called the SHE i.e. standard hydrogen electrode. We measure it at standard temperature and pressure conditions. The electrode potential of this electrode is referred as ${{E}^{\circ }}$ and is zero at any temperature. It consists of a platinum electrode immersed in a solution of hydrogen ion of concentration 1M.