Applications of Electrical Mobility

Electrical mobility is a vital concept in chemistry and has played a significant role in discovering batteries. If the concept of electron transfer was not discovered, then potable electrical energy storage equipment couldn’t have come into existence. Electrochemistry is a subject that deals with electricity generation from the energy liberated due to chemical reactions and utilising the electrical energy produced by these reactions in different chemical transformations.

This article will first explain the meaning of mobility in chemistry. Then we will explain the most important application of electron movability in a chemical reaction. Moreover, we will also give you a brief explanation about the theory of electrical mobility, which Robert Millikan defined.

Definition of Electrical mobility

The ability of charged particles, i.e., electrons and protons, to travel via a medium in reply to the electric field application is called electrical mobility. When the electrical field attracts the charged particles, they collide with atoms in their path. The collision with the atoms in their way due to the attraction in the electric field direction leads to the generation of drift velocity. Remember that electricity is the flow of electrons; hence they are charge bearers in every metal.

Mobility meaning is stated as the drift velocity acting per unit strength of the electric field. Therefore, the quicker electrons move in the electric field. The higher is their mobility. 

Theory of electric mobility

Robert Millikan demonstrated that charges are present in discrete units, and thus he stated that the electrical mobility directly varies with the average charge of the particle. A particle will be accelerated in an electrical field until it reaches the average velocity, called the drift velocity. The particle in the electric field will be accelerated according to the formula mentioned below.

Vd=μE

Here,

Vd = drift velocity measured in m/s

E= magnitude of electric field (V/m)

=mobility (m2V.S)

The mobility of Sodium, when reacted with water at 25 degrees Celsius, is 5.19 x 10-8. Thus, the sodium ion, under the application of an electric field of 1 V/m will have an average velocity of 5.19 x 10-8 m/s. 

Electrical movability is inversely proportional to the Stokes radius of an ion. Stokes radius is the radius of an ion that includes a molecule of any other solvent that moves with it. In the periodic table, the electrical mobility enhances from Li+ to Cs+. Thus it is evident that the Stokes radius reduces from lithium to caesium.

Daniel Cell

The Daniel cell uses the redox reaction to convert chemical energy into electrical energy. The chemical equation for the redox reaction happening in the Daniel cell is as follows.

Zns+Cu+2→Zn+2aq+Cus

The Daniel cell is one of the discoveries found due to the discovery of the concept of electric mobility. The electrical potential in the Daniel cell is 1.1V when the concentration of Zinc and copper ions is 1 mol dm-3. The Daniel cell is also known as the galvanic cell.

When an external potential is applied to the Galvanic cell, and a slow increment is done, it can be found that the reaction carries on until the opposite potential achieves the value of 1.1V. Once the reaction is completed, no current flows through the cell anymore. However, as the potential increases, the reaction starts again, but this time it is in the opposite direction, and the cell now becomes an electrolytic cell.

Galvanic Cells

Galvanic cells convert the chemical energy of a redox reaction into electrical energy by electron mobility. In a galvanic cell, the Gibbs energy of the redox reaction is converted to electrical work. The electrical work thus produced is used to run different appliances such as motor, water heater, television, etc.

Daniel’s cell discussed above is a Galvanic cell type, and the reaction equation is the same as mentioned above in the previous section. If we dig deep into the reaction equation of the Daniel cell, we will find out that the equation is a combination of two half-reactions. The two half-reactions are mentioned below.

Cu+2+2e-=Cu s

Zns=Zn+2+2e-

The two half-reactions happen in different areas of Daniel’s cell. Reduction reaction happens at the copper electrode, while oxidation reaction happens at the zinc electrode. Both portions of the cells where half-reaction occurs are called half-cells or redox couples. 

We can create several galvanic cells by employing the concept of electron mobility and Daniel’s cell. In every galvanic cell, the electrode is dipped into the electrolyte, and the electrodes are connected with the help of a wire. In addition to connecting the wire with the help of a wire, a voltmeter is also attached in between the wire. The electrolytes present in the half-cells are connected with the help of a salt bridge.

Conclusion

The discovery of electrical Mobility is a pivotal moment in human history. Today, the different key gadgets we use, such as mobile phones, laptops, tablets, etc., are powered using batteries that work on the principle of electrical movability. Robert Millikan’s discovery of the theory of electrical Mobility has helped future generations develop portable energy sources and have high power density. Moreover, The Galvanic cells are the foundation for the later discoveries in battery technology. Today, we can drive our cars on batteries, which is the outcome of the development caused by battery technology.