What is the Difference Between Ionic Mobility and Ionic Velocity?

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The key difference between ionic mobility and ionic velocity is that ionic mobility defines the ability of ions to move through a medium, while ionic velocity refers to the actual speed at which ions move in a specific medium under the influence of an electric field.

Ionic Mobility:

  • It is the ability of ions to move through a medium upon the application of an electric field.
  • Ionic mobility is proportional to the net charge of the particle.
  • It is affected by factors such as the size, shape, and charge of the ion, as well as the properties of the medium.
  • The separation of ions according to their mobility in gas phase is called ion mobility spectrometry, and in the liquid phase, it is called electrophoresis.

Ionic Velocity:

  • It is the actual speed at which ions move in a specific medium under the influence of an electric field.
  • Ionic velocity depends on the characteristics of the ion itself and the properties of the medium.
  • The velocity of the ion is given by the following equation: $$v = \frac{E \times q}{f}$$ where $$v$$ is the velocity, $$f$$ is the coefficient of friction, $$E$$ is the applied electric field (Volts/cm), and $$q$$ is the net charge on the ion.

In summary, ionic mobility describes the ability of ions to move through a medium, while ionic velocity refers to the actual speed at which ions move under the influence of an electric field. Both concepts are important for understanding the behavior of ions in various media and their contribution to conductance and electrophoresis.

Comparative Table: Ionic Mobility vs Ionic Velocity

The key difference between ionic mobility and ionic velocity lies in their definitions and the factors that influence them. Here is a comparison between the two:

Ionic Mobility Ionic Velocity
Ionic mobility defines the ability of ions to move through a medium upon the application of an electric field. Ionic velocity is the speed obtained by an ion moving through a medium under a unit electric field.
It is expressed as the ratio of the drift velocity to the magnitude of the applied electric field (μ = vd/E). It is expressed as the product of ionic mobility and the magnitude of the external electric field (Vd = μE).
Ionic mobility is used to separate ions according to their mobility in the gas phase (ion mobility) or in the liquid phase (electrophoresis). Ionic velocity, also known as drift velocity, is an average value and is measured in ms-1.

In summary, ionic mobility is a property that describes the ability of ions to move through a medium under an electric field, while ionic velocity is the actual speed at which ions move through a medium under a specific electric field.