Survey About Standard Electrode Potential

The standard electrode potential of an electrolyte is defined as the electromotive force which takes place when the two electrodes are completely immersed in it and at equal distances. This potential is measured numerically by applying an external voltage which allows this difference to be measured electrically against a standard potential such as a metallic hydrogen electrode. This method could be related to the equilibrium constant for the electrochemical reaction.

Define Standard Electrode Potential 

The standard electrode potential takes place in a specially designed electrochemical cell. For instance, 

Pressure = 1 atm

Temperature = 298K

Concentration = 1M

The ‘E°cell’ symbol represents the standard electrode potential of the given cell. 

Standard Electrode Potential’s importance in Chemistry

• Redox reactions are the base of all designed electrochemical cells. These are the combination of two and a half reactions.

• The oxidation reaction takes place at the given anode, including the loss of an electron.

• A reduction reaction tends to occur at the given cathode, due to which there is electrons gain. Therefore, the electrons move from the given anode and travel towards the cathode.

• Because of the present difference between the respective potential of individual electrodes, we see a rise in the electric potential between the cathode and the anode. 

• To measure the electrochemical cell’s potential, we use a special voltmeter. However, it is not possible to accurately measure a half-cell’s potential. 

• Also, note that this measured potential can vary due to changes in concentration, pressure, and temperature. 

• To find out a half-cell’s reduction potential, the necessity of standard electrode potential gets higher.

• To measure it, we can use a standard hydrogen electrode (SHE) which is a reference electrode. The value of electrode potential is zero volts for SHE. 

• To measure the electrode’s standard electrode potential, we can pair it with the designed SHE and measure the galvanic cell’s potential. 

Standard Electrode Potential Example

The computation of the standard electrode potential of a zinc terminal with the assistance of the common hydrogen electrode is outlined beneath.

Chemical equation for calculating Standard Electrode Potential as:

E0cell=E0red−E0ox

It tends to be noticed that the potential is calculated under normal and controlled conditions where we can note:

The temperature = 298K, 

Pressure = 1 atm, 

Concentration of electrolytes = 1M

Redox Reactions

When a specific redox reaction tends to be spontaneous, the ΔGo (Gibbs free energy) should have a standard negative value. The given equation describes it: 

The relative intensities of the oxidising and reducing agents remain unchanged when we examine how and what exactly happens to that same standard electrode potential. Turning the equation around, on the other hand, alters the sign of standard electrode potential, which might transform an unfavourable reaction into a spontaneous one or vice versa. For example, if we turn the Zn(s)+Cu(aq.)+2⟶Zn(aq.)+2+Cu(s) (the cell is reversed) and find the E°for zinc reduction in acidic solution (using our old friend from high school chemistry, Nernst’s equation), we find it is +0.76 V:

It is true that the sign of the standard electrode potential (E°) for a single reaction must be the same no matter what direction it is written in.

Consequently, the standard electrode potential of the anode and the cathode assist in foreseeing the immediacy of a cell in a reaction. It may very well be noticed that the ΔGo of a cell remains positive in electrolytic cells and negative in galvanic cells.

Conclusion

We covered all the essential information regarding standard electrode potential in this article. Furthermore, we have compiled a set of most common questions related to the topic that you must know the answers to. The standard electrode potential of an electrolyte is defined as the electromotive force which takes place when the two electrodes are completely immersed in it and at equal distances. This potential is measured numerically by applying an external voltage which allows this difference to be measured electrically against a standard potential such as a metallic hydrogen electrode. This method could be related to the equilibrium constant for the electrochemical reaction.