Distinguish between Drift Velocity and Mobility

Drift velocity is the movement of an object across a surface mainly due to air resistance and other forces. The drift velocity of a particle is the velocity per unit of distance that a particle will have in a given direction due to an applied electric field. It is important to distinguish between drift velocity and mobility because drift velocity is the average, instantaneous or total charge transport per unit of time. On the other hand, mobility refers to electron mobility, which denotes the range of speeds electrons can have in a particular medium, such as electric and magnetic fields.

Drift velocity:

The drift velocity of a particle is defined as the average velocity of the particle when moving in one direction, averaged over a time interval. This value helps us calculate how far we can expect the particle to move during that interval.

In practice, drift velocity is used in gas molecule modelling and diffusion coefficient calculations with small molecules suspended in liquids. It is also useful for calculating how much liquid will be transferred to the gaseous matter at different temperatures and pressures (Boiling Point; Vapour Pressure). The drift velocity is a key parameter in the stability of catalysts and certain processes such as aerosol formation.

One might wonder why we measure drift mobility instead of just using the mobility. The reason is that the drift velocity would be the same no matter what reaction takes place since it is a constant value per molecule. However, this does not mean we cannot use this value for different reactions (different molecules). Velocity per unit applies to any molecule for the same temperature and pressure.

Electron mobility:

Electron mobility is a measurement of how mobile the electron is in an atom. The higher it is, the more loosely held an electron is to its nucleus and the faster it will move in a particular substance.

In practice, one can use this to measure how energetic an atom or molecule is and how fast it can transfer energy through electronic processes. Furthermore, one can use this value to determine whether or not chemicals are attracted together because of their energy levels or if they are chemically stable. For example, the positive charge on an atom’s nucleus will attract electrons in a chemical bond. If the bonds are being formed with low electron mobility, it does not mean that there will not be a chemical bond. It only means that atoms in a certain group of chemical compounds will not form a chemical bond as often because they do not have as much energy potential to form this type of compound.

The drift velocity and mobility are not the same parameters. The drift velocity is a value per molecule at a certain temperature and pressure, while mobility is a value depending on the electric field strength, independent of temperature and pressure.

Difference between Drift Velocity and Mobility:

• Drift velocity is the average velocity of particles in a certain direction when moving in that direction.

Electron mobility is the speed at which an electron moves within a certain substance, determined by its interaction with the atoms of that substance.

• Drift velocity is also known as velocity per unit or velocity per molecule.

Electron mobility is also known as electron mobility.

• Driven by thermal energy, particles drift at a constant speed no matter what reaction occurs since it is a constant value per molecule. 

Electron mobility varies depending on the nature of the atom or molecule in the substance. It also varies depending on the temperature and pressure in an atom or molecule’s environment.

• Drift velocity is a constant value, while electron mobility can be altered by changing temperature or pressure.
• The more electrons there are in an atom or molecule, the higher the electron mobility will be. 

The more electrons there are in an atom or molecule, the higher the drift velocity will be.

• The more electrons there are in a substance, the higher the electron mobility.

The more particles there are in a substance, the higher the drift velocity.

• Drift velocity is expressed as m/s or cm/s or mm/s or inches/hour or m/(h·m) (the mass of an object divided by its acceleration). Electron mobility is expressed as cm²/(Vs) (the speed of electromagnetic waves through an electric current with an area of 1 cm²).
• Drift velocity calculates how much a substance will change from a liquid to a gaseous state at different temperatures and pressures to estimate boiling point and vapour pressure.

Electron mobility is used to determine the bond holding power of an atom and bonds that can be formed between atoms in a molecule.

Conclusion: 

The drift velocity and mobility are two different parameters. The drift velocity is determined by the temperature and pressure of a substance at a certain rate. In contrast, mobility is determined by the electric field strength, independent of temperature and pressure.

Drift velocity is the average velocity over some time. You can imagine it as a “truck” moving along with you, bumping into things as it goes.

Electrons have very high mobility and easy movement through a substance. This gives them the ability to react with other atoms or molecules, creating bonds between molecules while interacting.